Dietary antioxidants improve arteriogenic erectile dysfunction.

Most cases of erectile dysfunction (ED) are associated with oxidative stress risk factors such as diabetes mellitus, smoking, hypercholesterolaemia and hypertension. Our goal was to search for markers of oxidative stress in arteriogenic ED and examine the protective role of dietary antioxidants. Atherosclerosis-induced ED was developed in rabbits by balloon de-endothelialization of the iliac arteries. Ballooned and age-matched control animals were assigned into subgroups receiving pomegranate extract antioxidants in drinking water or tap water as placebo. After 8 weeks, penile blood flow and erectile activity were recorded. Erectile tissue relaxation, oxidative products, oxidative stress-responsive genes and structure were examined using organ bath, enzyme immunoassay, quantitative real-time polymerase chain reaction and transmission electron microscopy, respectively. Arterial ballooning caused diffused atherosclerosis, decreased intracavernosal blood flow and led to ED. Impairment of endothelium-dependent relaxation, diffused fibrosis, increased oxidative products, upregulation of superoxide dismutase (SOD) and aldose reductase (AR) gene expression, mitochondrial and endothelial structural damage and increased caveolae were evident in erectile tissues from atherosclerotic animals receiving placebo. Upregulation of antioxidant enzymes SOD and AR failed to protect ischaemic erectile tissue from oxidative injury. Pomegranate extract significantly improved intracavernosal blood flow, erectile activity, smooth muscle relaxation and fibrosis of the atherosclerotic group in comparison with the atherosclerotic group receiving placebo, but did not normalize them to the age-matched control levels. Pomegranate extract appeared more effective in diminishing oxidative products, preventing SOD and AR gene upregulation, and protecting mitochondrial, endothelial and caveolae structural integrity of the atherosclerotic group. Our data suggest the presence of oxidative stress in ED and a more efficient action of antioxidants on molecular and ultrastructural alterations than on distinct functional deficit and structural damage in the ischaemic penis.

Alterations in angiogenic growth factors and neuronal nitric oxide synthase expression in chronic cavernosal ischemia.

Our aim was to study anatomical and molecular changes at varying time points after the induction of cavernosal ischemia (CI) in a rabbit model of arteriogenic erectile dysfunction. Tissue structure and the expression of angiogenic and neurogenic genes were examined using immunostaining and reverse transcription-polymerase chain reaction (RT-PCR) analyses. We found a progressive increase of erectile connective tissue together with a decrease in smooth muscle cell content as the duration of CI increased. Immunohistochemical staining showed an increase in vascular endothelial growth factor (VEGF) levels at the early stages and a decrease at the later stages of ischemia. RT-PCR analysis of VEGF and neuronal nitric oxide synthase (nNOS) confirmed these results and showed nearly a two-fold increase in VEGF and nNOS mRNA levels in the early stages of CI with a decrease at the later stages of CI. On the other hand, mRNA levels of VEGF receptor, KDR, decreased approximately by 50% over the course of CI. Our studies showed that the cellular and molecular responses of the erectile tissue to short-term ischemia are different than those seen after long-term ischemia. The dramatic reduction in KDR expression suggests that the cavernosal endothelium is very sensitive to ischemia. The similar changes in VEGF and nNOS expression over the course of CI suggest a tissue-defensive mechanism to CI via the VEGF and NO pathways. Taken together, this study suggests that supplementation of VEGF at earlier stages of ischemia may restore the damaged endothelial cells of the corpus cavernosum and support tissue perfusion.

Decreased circulating levels of estrogen alter vaginal and clitoral blood flow and structure in the rabbit.

Aging and menopause related decline in circulating levels of estrogen has been shown to adversely affect female sexual arousal function. Our aim was to study the effects of circulating levels of estrogen on the hemodynamic mechanism of vaginal and clitoral engorgement and on the structure of the vaginal and clitoral cavernosal tissue in the rabbit. New Zealand White female rabbits (3.5-4 kg) were randomly divided into three groups with five rabbits in each group: control; bilateral oophorectomy; bilateral oophorectomy undergoing subcutaneous injection of estrogen (40 microg/kg/day). After 6 weeks, the serum levels of 17 beta-estradiol were measured and systemic blood pressure was monitored. Vaginal and clitoral cavernosal blood flows were measured with laser Doppler flowmeter before and after pelvic nerve stimulation. Cross sections of the clitoris and vagina were processed for histologic examination and histomorphometric image analysis. Serum level of 17 beta-estradiol (pg/ml; mean+/-s.d.) revealed a significant decrease in the oophorectomy group (25.4+/-5.1) compared with the control (38.5+/-7.6) and estrogen replacement (115.9+/-57.3) groups (P<0.05). Nerve stimulation-induced peak vaginal and clitoral intracavernosal blood flows in the oophorectomy group (28.9+/-16.3 and 6.1+/-1.4, respectively) were significantly less than those recorded in the control (48.9+/-6.5 and 11.0+/-2.4, respectively) or estrogen replacement (48.7+/-12.2 and 10.1+/-2.8, respectively) group (P<0.05). In histology, marked thinning of the vaginal epithelial layers, decreased vaginal submucosal microvasculature, and diffuse clitoral cavernosal fibrosis were evident in the oophorectomy group but not in the estrogen supplement and control groups. In histomorphometry, the percentage of clitoral cavernosal smooth muscle in the oophorectomy group (49.6+/-6.2) was significantly decreased compared with the control (56.8+/-2.6) and estrogen replacement (58+/-3.0) groups (P<0.05). Our studies show that decline in circulating levels of estrogen impairs the hemodynamic mechanism of vaginal and clitoral engorgement and leads to histopathologic changes in the vagina and clitoral cavernosal tissue. These observations suggest that decreased circulating levels of estrogen, a physiologic change in the menopausal state, may play a role in the development of female sexual arousal dysfunction.

Chronic ischemia alters prostate structure and reactivity in rabbits.

PURPOSE: Autopsy studies performed in men older than 80 years old have demonstrated that 90% have histological evidence of benign prostatic hyperplasia. Despite this fact pressure flow studies in men of this age who are referred for the evaluation of lower urinary tract symptoms have shown that only 40% have evidence of bladder outlet obstruction. To our knowledge the specific features of benign prostatic hyperplasia responsible for bladder outlet obstruction are not known. To investigate the possible etiological factors responsible for bladder outlet obstruction we determined whether chronic ischemia alters the structural and functional properties of the prostate. MATERIALS AND METHODS: Male New Zealand White rabbits weighing 3.5 to 4 kg. were divided into a chronic prostate ischemia (12), hypercholesterolemia (8) and age matched control (8) group. The chronic prostate ischemia group underwent balloon endothelial injury of the iliac arteries and received a 0.5% cholesterol diet, the hypercholesterolemia group received a 0.5% cholesterol diet only and controls received a regular diet. After 12 weeks using anesthesia iliac artery and prostatic blood flow was measured by an ultrasonic and laser Doppler flowmeter, respectively. The animals were then sacrificed and the prostate was processed for histological evaluation, immunohistochemical staining for vascular endothelial growth factor expression and organ bath studies. RESULTS: Iliac artery and prostatic blood flow was significantly decreased in the chronic prostate ischemia compared with the hypercholesterolemia and control groups. Histological findings included thickening and fibrosis of the prostatic stroma and cystic atrophy of the epithelium in the chronic prostate ischemia group as well as minor thickening of the stroma in the hypercholesterolemia group. These structural changes correlated with decreased vascular endothelial growth factor expression. Organ bath studies showed that chronic ischemia and to a lesser extent hypercholesterolemia impaired electrical field stimulation induced neurogenic relaxation of the prostatic tissue. Neurogenic relaxation of the prostatic tissue was improved by combined treatment with indomethacin and L-arginine in the hypercholesterolemia but not in the chronic prostate ischemia group. Nitric oxide donor sodium nitroprusside produced comparable relaxation in all 3 groups. CONCLUSIONS: Chronic ischemia causes marked changes in prostatic structure and contractility. Ischemia induced glandular atrophy was consistently associated with decreased vascular endothelial growth factor expression. Decreased relaxation of the ischemic tissue to electrical field stimulation appears to involve the nitric oxide pathway. The nitric oxide precursor L-arginine reversed hypercholesterolemia induced impairment of prostatic tissue relaxation. Our study suggests that chronic ischemia results in thickening and fibrosis of the prostate, changing its mechanical properties. Chronic ischemia also impairs neurogenic relaxation in the prostate. We discuss the possible relationship of these changes to clinical bladder outlet obstruction.

Systemic administration of apomorphine improves the hemodynamic mechanism of clitoral and vaginal engorgement in the rabbit.

Clitoral and vaginal engorgement during sexual stimulation depend in part on the increase of arterial inflow. It has been shown that apomorphine (APO), a non-selective dopamine receptor agonist, produces penile erection by activating dopaminergic receptors in the central nervous system. Our aim was to study whether systemic administration of APO improves the hemodynamic mechanism of clitoral and vaginal engorgement in the rabbit. Female New Zealand white rabbits (3.5-4 kg, n=6) were anesthetized. To examine sexual arousal function, the vaginal/clitoral branch of the pelvic nerve was stimulated electrically and maximal increases in clitoral intracavernosal and vaginal wall blood flows and pressures were recorded. After this APO was injected intravenously in a dose-response manner (0.05, 0.1, 0.2, 0.3 and 0.4 mg/kg) and nerve stimulation was performed after each dose. Changes in nerve-stimulated increase of clitoral intracavernosal and vaginal blood flows and pressures after APO was compared to those recorded before APO. Electrical stimulation of the vaginal/clitoral branch of the pelvic nerve significantly increased clitoral intracavernosal and vaginal wall blood flows in the rabbit. Intravenous administration of APO caused concentration dependent increase in nerve stimulation-induced peak clitoral intracavernosal and vaginal wall blood flows reaching to statistically significant at the concentration of 0.1 and 0.2 mg/kg. Inravenous administration of APO greater than 0.2 mg/kg (0.3 and 0.4 mg/kg) were less effective or produced adverse effects on clitoral intracavernosal and vaginal wall blood flows. Intravenous APO also tended to increase nerve-stimulated increase of clitoral intracavernosal and vaginal wall pressures, but the effect was not statistically significant. In conclusion, our studies suggest that systemic administration of APO may improve clitoral and vaginal engorgement by increasing clitoral intracavernosal and vaginal wall arterial inflow.

Atherosclerosis-induced chronic arterial insufficiency causes clitoral cavernosal fibrosis in the rabbit.

In our previous studies we found that aging-associated fibrosis of clitoral cavernosal tissue correlated with the prevalence of cardiovascular disease in elderly women. The aim of this study was to determine specifically, arterial insufficiency-related structural changes of clitoral cavernosal tissue in a rabbit model. New Zealand white female rabbits were divided into clitoral cavernosal ischemia (CCI, n = 5) and control (n = 5) groups. The CCI group underwent balloon endothelial injury of the iliac arteries and received 0.5% cholesterol diet. The control group received a regular diet. After 16 weeks, arteriography was performed then the animals were sacrificed. The iliac arteries and the entire clitoris were removed. Cross-sections of the iliac arteries and clitoris were processed for histologic evaluation The percentage of smooth muscle and connective tissue in trichrome stained sections of clitoral cavernosal tissue was determined by computer-assisted histomorphometry. Arteriography revealed diffused occlusive disease in the common iliac, internal iliac and pudendal arteries in the CCI group. Histology showed that arterial occlusive disease spreads from the site of balloon injury to the smaller branches involving the clitoral cavernosal arteries. Diffuse fibrosis was observed in the clitoral cross-sections of the CCI group. The percentage of clitoral cavernosal smooth muscle (mean +/- standard error) in the CCI group (53% +/- 0.9%) was significantly decreased compared with the control group (62% +/- 0.8%) (P = 0.0001). Chronic clitoral cavernosal ischemia causes significant fibrosis and loss of smooth muscle in the clitoral cavernosal tissue. These findings suggest that chronic clitoral cavernosal arterial insufficiency may play a role in the pathophysiology of female sexual arousal disorders.

Isoprostane 8-epi PGF2alpha, a product of oxidative stress, is synthesized in the bladder and causes detrusor smooth muscle contraction.

Isoprostane 8-epi PGF2alpha is a product of oxidative stress that causes potent smooth muscle contraction. Its production increases in conditions associated with oxidative stress such as in diabetes, smoking, and aging. The aim was to study whether the urinary bladder synthesizes isoprostane 8-epi PGF2alpha and releases to the urine and whether isoprostane 8-epi PGF2alpha causes bladder smooth muscle contraction. Urine samples were obtained transurethrally from 12 male New Zealand white rabbits for measurement of isoprostane 8-epi PGF2alpha levels. To examine whether bladder synthesizes isoprostane 8-epi PGF2alpha, both ureters were ligated, then the bladder was washed 5 times by filling and emptying with normal saline. Bladder was refilled with normal saline, and at 5 minutes a bladder washout sample was taken. After this, the bladder was contracted by nerve stimulation periodically for 30 minutes, and then another washout sample was taken. Strips of bladder tissues were processed for study of isoprostane 8-epi PGF2alpha production in tissue culture chambers and for isometric tension measurements in the organ bath. Enzyme immunoassay (EIA) revealed a remarkable amount of isoprostane 8-epi PGF2alpha in the rabbit urine. EIA of washout samples showed that the bladder synthesizes isoprostane 8-epi PGF2alpha and its production increases with nerve stimulation-induced contractions. EIA of samples from the tissue culture media showed that bladder strips synthesize isoprostane 8-epi PGF2alpha in vitro. Electrical field stimulation (EFS) significantly increased the synthesis and release of isoprostane 8-epi PGF2alpha by the bladder strips. In the organ bath, isoprostane 8-epi PGF2alpha caused concentration-dependent contraction of bladder tissue. While the threshold contraction required smaller concentration of isoprostane 8-epi PGF2alpha (3 nmol) than carbachol (10 nmol), the amplitude of contraction to carbachol was greater than isoprostane 8-epi PGF2alpha. Our studies show that the rabbit bladder synthesizes isoprostane 8-epi PGF2alpha and releases it to the urine. Production of isoprostane 8-epi PGF2alpha in the bladder increases with nerve stimulation-induced contraction. Exogenous isoprostane 8-epi PGF2alpha causes significant bladder smooth muscle contraction. Our findings necessitate further studies to evaluate the possible role of oxidative stress and increased isoprostane 8-epi PGF2alpha production in bladder dysfunction. Neurourol. Urodynam. 19:43-51, 2000.

Overactivity and structural changes in the chronically ischemic bladder.

PURPOSE: Our aim was to study the effect of chronic ischemia on bladder contraction and detrusor smooth muscle reactivity. The relationship between structural damage and functional changes in the chronically ischemic bladder was also investigated. MATERIAL AND METHODS: Male New Zealand White rabbits were divided into arterial injury (AI), hypercholesterolemia (Hch) and control groups. The AI group (n = 18) underwent balloon endothelial injury of the iliac arteries and received a 0.5% cholesterol diet. The Hch group (n = 8) received a 0.5% cholesterol diet alone. The control group (n = 8) received a regular diet. After 16 weeks, iliac artery and bladder wall blood flows were recorded. Cystometrograms and arteriography were obtained and bladder tissues were processed for isometric tension measurement in the organ bath and for histological evaluation. RESULTS: At 16 weeks, blood flow through the iliac arteries was significantly reduced in the AI group compared with the Hch and control groups. In the AI group, 8 animals developed severe bladder ischemia (SBI) defined as greater than 60% decrease in bladder blood flow, 7 animals developed moderate bladder ischemia (MBI) defined as 40 to 60% decrease in bladder blood flow, and 3 animals failed to develop significant bladder ischemia (<40% decrease in bladder blood flow). In the control animals, bladder blood flow increased prior to contraction, decreased during contraction and rebounded to baseline levels after contraction. In animals with MBI and SBI, the increase in bladder blood flow prior to contraction and the rebound of blood flow after contraction, both seen in control animals, were diminished. Detrusor overactivity (significant increase in the frequency of spontaneous bladder contractions) was observed in the MBI group and impaired bladder contraction in the SBI group. In the organ bath, bladder strips from the MBI group demonstrated increased contractile response to carbachol and electrical field stimulation (EFS) while bladder strips from the SBI group showed impaired contractility. Hch alone produced only short-lived ischemia during bladder contraction and caused significantly lesser functional changes compared with those seen in MBI. Histological examination showed atherosclerotic occlusion in the iliac arteries and bladder microcirculation and marked disruption of urothelium in the MBI and SBI groups. Severe fibrosis was seen in bladder tissue from the SBI group, moderate fibrosis in tissue from the MBI group and mild fibrosis in tissue from the Hch group. CONCLUSIONS: Our studies show that chronic MBI is associated with detrusor overactivity and increased smooth muscle contractility to carbachol and EFS while chronic SBI is associated with impaired detrusor contraction. The mechanism of chronic ischemia-induced bladder dysfunction is not known and may involve multiple physiologic and structural changes in the bladder nerves, receptors and contractile components. Our studies suggest that ischemia-induced structural damage in the urothelium and possible chronic exposure of the underlying tissue and nerves to the urine may also play a role in MBI-induced detrusor overactivity. SBI-induced impairment of bladder contraction may involve, in part, extensive fibrosis and loss of bladder smooth muscle. Histopathophysiologic changes in bladder tissue from our MBI model are similar to those seen in patients with detrusor instability, suggesting that chronic ischemia may play a role in the development of idiopathic detrusor instability.

Atherosclerosis-induced chronic ischemia causes bladder fibrosis and non-compliance in the rabbit.

PURPOSE: The overall goal was to determine whether chronic ischemia and hypercholesterolemia interfere with bladder function and structure. The roles of atherosclerosis-induced chronic ischemia and hypercholesterolemia in bladder fibrosis and non-compliance were studied in the rabbit. The relationship between ischemia-induced changes in the expression of transforming growth factor-beta1 (TGF-beta1) and basic fibroblast growth factor (bFGF) and the severity of bladder fibrosis was also investigated. MATERIALS AND METHODS: Male New Zealand White rabbits were divided into chronic bladder ischemia (CBI, n = 11), hypercholesterolemia (Hch, n = 8) and control (n = 8) groups. The CBI group underwent balloon endothelial injury of the iliac arteries and received a 0.5% cholesterol diet. The Hch group received a 0.5% cholesterol diet alone. The control group was placed on a regular diet. After 16 weeks, iliac artery and bladder wall blood flow measurements, cystometrograms (CMG) and aorto-iliac arteriograms were obtained in all animals. Iliac arteries and bladder tissues were processed for histological staining and computer-assisted histomorphometric image analysis. The expressions of TGF-beta1 and bFGF in bladder tissue were determined by immunohistochemical staining utilizing monoclonal antibodies. RESULTS: At 16 weeks, arteriography and histology showed significant diffuse atherosclerotic occlusive disease of the aorto-iliac arteries in the CBI group. Iliac artery and bladder wall blood flows were significantly decreased in the CBI group compared with the Hch and control groups. Atherosclerosis-induced CBI shifted the volume-pressure curve to the left and caused severe bladder fibrosis. Hypercholesterolemia also caused fibrosis and non-compliance but to a much lesser extent compared with those caused by CBI. In histomorphometry, the percentage of detrusor smooth muscle was moderately decreased in the Hch group and severely decreased in the CBI group compared with the control group. In immunohistochemical stains of bladder tissues, bFGF expression was similar in the three groups of animals. TGF-beta1 expression was significantly greater in bladder tissues from the CBI group compared with the Hch and control groups. CONCLUSIONS: Our studies show that atherosclerosis-induced chronic ischemia increases TGF-beta1 expression in the bladder leading to fibrosis, smooth muscle atrophy and non-compliance. Hypercholesterolemia also interferes with bladder structure and compliance but to a significantly lesser extent compared with CBI. Our studies suggest that arterial insufficiency and hypercholesterolemia, common aging-associated disorders, may play important roles in the pathophysiology of voiding dysfunction in the elderly.

Relative roles of cyclooxygenase and nitric oxide synthase pathways in ischemia-induced increased contraction of cavernosal smooth muscle.

PURPOSE: To study the mechanism of chronic ischemia-induced increased cavernosal smooth muscle contraction in an animal model of vasculogenic erectile dysfunction. MATERIALS AND METHODS: New Zealand White rabbits were divided into control (n = 6, fed with a regular diet), hypercholesterolemic (n = 9, fed with a diet containing 0.5% cholesterol) and chronic cavernosal ischemia (CCI, n = 10, underwent balloon de-endothelialization of iliac arteries and received a diet containing 0.5% cholesterol) groups. After 16 weeks, the relationship between iliac artery blood flow and cavernosal smooth muscle contraction was studied. The roles of cyclooxygenase and nitric oxide (NO) pathways in chronic ischemia-induced increased smooth muscle contraction were also examined. RESULTS: Iliac artery blood flow in the CCI group was significantly reduced compared with the control and hypercholesterolemic groups. Hypercholesterolemia alone did not affect cavernosal smooth muscle contraction. Atherosclerosis-induced chronic cavernosal arterial insufficiency did not affect contraction to norepinephrine while causing a significant increase in electrical field stimulation-induced neurogenic contraction. Inhibition of the cyclooxygenase pathway by indomethacin decreased electrical field stimulation-induced contraction in all animals but failed to normalize the differences between CCI and control groups. In the presence of indomethacin, L-arginine decreased electrical field stimulation-induced contraction in the control and hypercholesterolemic groups but not in the CCI group. In the presence of indomethacin, treatment with nitric oxide synthase (NOS) inhibitor, N(G)-monomethyl-L-arginine (L-NMMA), increased electrical field stimulation-induced contraction in all groups. This effect of L-NMMA on smooth muscle contraction was significantly greater in the control and hypercholesterolemic groups compared with the CCI group. After tissue treatment with L-NMMA, the magnitude of contraction in cavernosal tissue from control and hypercholesterolemic groups was similar to those observed in the CCI group. CONCLUSIONS: Mechanism of chronic ischemia-induced increased cavernosal smooth muscle contraction involves increased output of constrictor eicosanoids and impairment of the inhibitory influence of NO pathway in cavernosal tissue.

Histomorphometric analysis of age-related structural changes in human clitoral cavernosal tissue.

PURPOSE: To characterize age-associated histological changes of human clitoral cavernosal tissue and to determine whether age-related histological changes of clitoral cavernosal tissue correlate with vascular disease-related mortality. MATERIALS AND METHODS: Human clitorises were obtained from 15 fresh cadavers (age: 11 to 90 years) and from 3 patients undergoing clitoral surgery (age: 6 months to 15 years). Cross sections of the clitorises were stained with Masson's trichrome and utilized for computer assisted histomorphometric image analysis to determine the clitoral cavernosal content of smooth muscle and connective tissue. RESULTS: These studies revealed a strong link between increase in age and decreased clitoral cavernosal smooth muscle fibers. In histomorphometry, the percentage of clitoral cavernosal smooth muscle (mean +/- standard error) in an age group of 6 months to 15 years (n = 4) was 65+/-1.5, in 44 to 54 years (n = 7) was 50+/-1.2, and in 55 to 90 years (n = 7) was 37+/-1.3 (ANOVA, p = 0.0001). In the 18 tissues studied, decrease in the percentage of clitoral cavernosal smooth muscle significantly correlated with increase in age (simple regression, r = 0.61). In the age group of 44 to 90 years, clitoral cavernosal fibrosis was significantly greater in the presence of cardiovascular disease-related mortality compared with those without cardiovascular disease-related mortality. CONCLUSION: This study shows that aging women undergo histological changes in clitoral cavernosal erectile tissue. Vascular risk factors may adversely affect the structure of clitoral cavernosal tissue. These findings may be of importance in the pathophysiology of age-associated female sexual arousal disorders.

Mechanisms of ischemia-induced cavernosal smooth muscle relaxation impairment in a rabbit model of vasculogenic erectile dysfunction.

PURPOSE: To determine the effects of hypercholesterolemia and atherosclerosis-induced chronic cavernosal arterial insufficiency on cavernosal smooth muscle tone, nitric oxide synthase (NOS) activity and cavernosal tissue synthesis of constrictor eicosanoids. To study whether inhibition of the cyclooxygenase pathway by indomethacin and tissue treatment with nitric oxide (NO) precursor L-arginine improve hypercholesterolemia and ischemia-induced impaired endothelium-dependent and neurogenic relaxation of cavernosal tissue. MATERIALS AND METHODS: New Zealand White rabbits were divided into control (n = 10, fed a regular diet), hypercholesterolemia (Hch, n = 13, fed a diet containing 0.5% cholesterol) and chronic cavernosal ischemia (CCI, n = 14) groups. The CCI group underwent balloon deendothelialization of iliac arteries and received a diet containing 0.5% cholesterol. After 16 weeks, we examined the effects of Hch and balloon de-endothelialization induced arterial occlusive disease on iliac arterial blood flow, reactivity of cavernosal tissue, cavernosal NOS activity and cavernosal tissue synthesis of constrictor eicosanoids. RESULTS: Histology revealed significant atherosclerotic arterial occlusive disease in the CCI group. Iliac artery blood flow in the CCI group was significantly reduced compared with the control and Hch groups. In the Hch and CCI groups, endothelium-dependent relaxation of cavernosal tissue to acetylcholine was significantly reduced compared with the control group. Electrical field stimulation-induced neurogenic relaxation and cavernosal NOS activity were significantly reduced in the CCI group but not in the Hch group. The basal release of cavernosal constrictor eicosanoids, prostaglandin F2alpha (PGF2alpha) and thromboxane A2 (TXA2) was significantly increased in the CCI group. Indomethacin increased endothelium-dependent relaxation in all groups and neurogenic relaxation in the CCI group, but failed to normalize the differences in relaxation between treated and control groups. In the presence of indomethacin, L-arginine improved endothelium-dependent relaxation of cavernosal tissue in the Hch group but did not normalize endothelium-dependent or neurogenic relaxations in the CCI group. Relaxation to NO donor sodium nitroprusside and papaverine was similar in cavernosal tissue from all groups. CONCLUSIONS: Impairment of endothelium-dependent relaxation by Hch occurs secondary to disruption of the NO formation in cavernosal endothelium. Improvement of endothelium-dependent relaxation by L-arginine may suggest lack of availability of L-arginine in cavernosal tissue from the Hch animals. Impairment of endothelium-dependent and neurogenic relaxation by CCI occurs secondary to disruption of the NO formation due to an alteration in the expression or activity of NOS and increased output of constrictor eicosanoids in cavernosal tissue. These studies show that Hch and atherosclerosis-induced chronic cavernosal arterial insufficiency, beyond decreasing cavernosal perfusion pressure, also adversely affect smooth muscle relaxation mechanisms in cavernosal tissue.

Preliminary report on the development and characterization of rabbit clitoral smooth muscle cell culture.

PURPOSE: Scientific model systems for physiological evaluation and investigation of pathophysiologies in clitoral function have been limited. The aim was to develop a New Zealand White rabbit clitoral corpus cavernosum smooth muscle cell culture. METHODS: Clitoral corpus cavernosum erectile tissue was harvested and placed in culture. Clitoral smooth muscle cells which migrated out from explants were grown to confluence and subcultured. Characterizations were performed by morphological and biochemical analyses. RESULTS: The cells exhibited typical morphologic characteristics of smooth muscle cells. Indirect immunofluorescence studies confirmed the presence of a-smooth muscle cell actin. Androgen and estrogen receptors were detected by specific antibodies and binding studies. The cells expressed subtypes of TGF-beta receptors. Treatment with 80 pM TGF-beta 1 24 h resulted in induction and/or increased availability of TGF-beta receptors. CONCLUSIONS: An in-vitro cell culture system using rabbit clitoral smooth muscle cells was developed. These smooth muscle cells retain their biochemical and functional integrity. This in-vitro cell culture system may facilitate studies aimed at understanding the molecular basis of female sexual function.

Cavernosal expandability is an erectile tissue mechanical property which predicts trabecular histology in an animal model of vasculogenic erectile dysfunction.

PURPOSE: Reliable, clinically available, non-invasive measurements able to predict trabecular histology without the need for erectile tissue biopsy would improve impotence management, since the percentage of trabecular smooth muscle content has been shown to be associated with corporal veno-occlusive dysfunction. The purpose was to identify whether the erectile tissue mechanical property, cavernosal expandability, correlated with the percentage of trabecular smooth muscle content in an animal model of hypercholesterolemia and ischemic-induced corporal fibrosis. MATERIALS AND METHODS: New Zealand White rabbits (6 to 7 months old, 3 to 3.5 kg.), were divided into control (n = 7), hypercholesterolemic (n = 5, 0.5% cholesterol diet) and atherosclerotic groups (n = 8, 0.5% cholesterol diet with balloon de-endothelialization). At 16 weeks, the corpora cavernosa were removed en bloc and submerged in physiologic salt solution, and volume-pressure data were plotted at 20 mm. Hg pressure intervals under trabecular smooth muscle relaxation. Cavernosal expandability, X, (the measure of the ability to achieve high corporal expansion at relatively low intracavernosal pressure) and tunical distensibility, V(E)/V(F), (relative volume of fully erect to flaccid penis) were calculated. Erectile tissue was assessed by computer-assisted color histomorphometry with Masson's trichrome stained sections (30 to 45 high power fields/animal) to assess percentage of trabecular smooth muscle content. RESULTS: The overall mean percentage of trabecular smooth muscle content and mean cavernosal expandability values were 45.4 +/- 1.6, 39.2 +/- 0.9, 33.9 +/- 0.6 and 0.0165 +/- 3.04 x 10(-3), 0.0116 +/- 1.63 x 10(-3), 0.0118 +/- 1.26 x 10(-3) mm. Hg(-1) for the control, hypercholesterolemic and atherosclerotic groups, respectively (r = 0.87). Significant differences in trabecular smooth muscle content were observed among all 3 groups, and in cavernosal expandability, between control and atherosclerotic groups, as well as between control and hypercholesterolemic groups but not between atherosclerotic and hypercholesterolemic groups. CONCLUSIONS: The erectile tissue mechanical property, cavernosal expandability, correlated with erectile tissue structural quality. Since cavernosal histology has been shown to predict corporal veno-occlusive function, it is hypothesized that the measurement of cavernosal expandability may become a valuable functional clinical parameter in the diagnosis and treatment of men with erectile dysfunction.

Vasculogenic female sexual dysfunction: the hemodynamic basis for vaginal engorgement insufficiency and clitoral erectile insufficiency.

OBJECTIVE: Organic female sexual dysfunction may be related in part to vasculogenic impairment of the hypogastric-vaginal/clitoral arterial bed. The aim was to develop an animal model of vaginal engorgement insufficiency and clitoral erectile insufficiency. METHODS: Pelvic nerve stimulated vaginal engorgement and clitoral erection were achieved in control (normal diet, n = 8) and atherosclerotic (balloon injury of aorto-iliac arteries and 0.5% cholesterol diet, n = 7) New Zealand White female rabbits. After 16 weeks, novel hemodynamic variables including vaginal wall and clitoral blood flow, vaginal wall and clitoral intracavernosal pressure, vaginal length, vaginal luminal pressure, blood levels of cholesterol and triglycerides, aorto-iliac angiography and vaginal wall and clitoral erectile tissue histology were recorded in the two groups. RESULTS: Concerning pelvic nerve stimulated vaginal hemodynamic changes, there was significantly less increase in blood flow (ml/min/100 gm tissue), wall pressure (mmHg) and length changes (mm) in atherosclerotic (9.3 +/- 3.7, 4.8 +/- 3.8, 67.3 +/- 8.3) compared to control (13.9 +/- 4.5, 5.5 +/- 2.6, 74.1 +/- 10.0) animals respectively. Histologic examination of clitoral erectile tissue demonstrated cavernosal artery atherosclerotic changes and diffuse vaginal and clitoral fibrosis. Aorto-iliac angiography in atherosclerotic animals revealed diffuse moderate to severe atherosclerotic occlusion. CONCLUSIONS: Vaginal engorgement and clitoral erection depend on increased blood inflow. Atherosclerosis is associated with vaginal engorgement insufficiency and clitoral erectile insufficiency.

Relationship between cavernosal ischemia and corporal veno-occlusive dysfunction in an animal model.

PURPOSE: It has been postulated that cavernosal tissue ischemia secondary to arterial occlusive disease is associated with corporal veno-occlusive dysfunction. The goal was to correlate, for the first time, direct local intracavernosal blood flow measurements as a measure of cavernosal tissue perfusion with the integrity of corporal veno-occlusion in an animal model of vasculogenic impotence. MATERIALS AND METHODS: The New Zealand White rabbit model of vasculogenic impotence was utilized (7 control, 9 atherosclerotic). After 16 weeks, intracavernosal blood flow was recorded directly by laser Doppler flowmetry. The relationships among peak intracavernosal blood flow, equilibrium intracavernosal pressure and corporal veno-occlusive function (as determined by intracavernosal pressure decay) were examined. RESULTS: Significant differences in the atherosclerotic compared to control animals were noted in iliac artery blood flow (12 +/- 4 vs 31 +/- 7 ml./min.), peak intracavernosal blood flow during erection (16 +/- 7 vs 25 +/- 4 ml./min./100 gm. tissue), equilibrium intracavernosal pressure (48 +/- 11 vs 72 +/- 6 mm. Hg) and intracavernosal pressure decay (57 +/- 17 vs 36 +/- 8 mm. Hg). Peak intracavernosal blood flow during erection was found significantly related to both equilibrium pressure (r = 0.75) and cavernosal pressure decay (r = -0.8). CONCLUSIONS: Abnormal intracavernosal blood flow (cavernosal ischemia) secondary to arterial occlusive disease predicts abnormal veno-occlusive function and poor erection quality.

Study of etiologic relationship of arterial atherosclerosis to corporal veno-occlusive dysfunction in the rabbit.

PURPOSE: The aim of this study was to explore the possible etiologic relationship of hypercholesterolemia and atherosclerosis to corporal veno-occlusive dysfunction. MATERIALS AND METHODS: In the New Zealand White rabbit, the competence of the corporal veno-occlusive mechanism was examined at various intervals after exposure to control diet, high cholesterol diet, or aortoiliac atherosclerosis. RESULTS: Initially, all animals showed normal erectile function and corporal veno-occlusion. After 8 weeks and 16 weeks, the control animals preserved normal erection and corporal veno-occlusion, while most of the hypercholesterolemic and atherosclerotic animals developed corporal veno-occlusive dysfunction. The incidence of corporal veno-occlusive dysfunction in the hypercholesterolemia and atherosclerotic animals increased with time. CONCLUSIONS: This study suggests that a close relationship exists between prolonged atherosclerotic occlusion of major penile arteries and the development of corporal veno-occlusive dysfunction. Ischemia-induced corporal veno-occlusive dysfunction may be the result of alterations in corporal smooth muscle relaxation or changes in the structure and fibroelastic properties of erectile tissue.

Canine bladder blood flow and oxygenation: changes induced by filling, contraction and outlet obstruction.

PURPOSE: To study changes in bladder blood flow and oxygenation associated filling, contraction and outlet obstruction. MATERIALS AND METHODS: Intravesical pressure, bladder flow, bladder wall oxygen tension, iliac artery blood flow and systemic blood pressure were measured simultaneously in anesthetized dogs (N = 18). RESULTS: In the empty bladder, blood flow and oxygen tension in the bladder were greater than at the dome with and without outlet obstruction. Bladder filling caused a significant decrease in bladder wall blood flow and oxygen tension with or without outlet obstruction. Spontaneous bladder contractions resulted in a marked decrease in bladder wall perfusion in the obstructed bladder but not in the unobstructed bladder. Pelvic nerve stimulation produced strong bladder contractions associated with significant drop in bladder wall perfusion and bladder oxygenation in both the open and closed bladder neck models. Little change was noted after stimulation of the hypogastric nerve. CONCLUSIONS: Bladder distention and contraction, especially against a closed bladder neck, induce significant ischemia and hypoxia of the bladder wall. These findings may be important in the pathophysiology of a variety of common clinical problems.

Direct measurement of blood flow in the human bladder.

PURPOSE: We evaluated blood flow in the human bladder. MATERIALS AND METHODS: In 8 surgical cases a laser Doppler flow probe was placed in the bladder dome and anterior wall. In 10 endoscopic cases the flow probe was placed in the bladder trigone and lateral wall. RESULTS: Bladder filling resulted in reduced mean blood flow in the dome and anterior wall. After prostatectomy blood flow decreased in the dome but not the anterior wall. During endoscopy bladder filling resulted in diminished blood flow. CONCLUSIONS: Laser Doppler flowmetry can measure blood flow changes in the human bladder.