Perivascular adipose tissue-derived nitric oxide compensates endothelial dysfunction in aged pre-atherosclerotic apolipoprotein E-deficient rats.

BACKGROUND AND AIMS: Atherosclerosis is a major contributor to global mortality and is accompanied by vascular inflammation and endothelial dysfunction. Perivascular adipose tissue (PVAT) is an established regulator of vascular function with emerging implications in atherosclerosis. We investigated the modulation of aortic relaxation by PVAT in aged rats with apolipoprotein E deficiency (ApoE-/-) fed a high-fat diet as a model of early atherosclerosis. METHODS AND RESULTS: ApoE-/- rats (N = 7) and wild-type Sprague-Dawley controls (ApoE+/+, N = 8) received high-fat diet for 51 weeks. Hyperlipidemia was confirmed in ApoE-/- rats by elevated plasma cholesterol (p < 0.001) and triglyceride (p = 0.025) levels. Early atherosclerosis was supported by increased intima/media thickness ratio (p < 0.01) and ED1-positive macrophage influx in ApoE-/- aortic intima (p < 0.001). Inflammation in ApoE-/- PVAT was characteristic by an increased [18F]FDG uptake (p < 0.01), ED1-positive macrophage influx (p = 0.0003), mRNA expression levels of CD68 (p < 0.001) and IL-1ß (p < 0.01), and upregulated iNOS protein (p = 0.011). The mRNAs of MCP-1, IL-6 and adiponectin remained unchanged in PVAT. Aortic PVAT volume measured with micro-PET/CT was increased in ApoE-/- rats (p < 0.01). Maximal endothelium-dependent relaxation (EDR) to acetylcholine in ApoE-/- aortic rings without PVAT was severely impaired (p = 0.012) compared with controls, while ApoE-/- aortic rings with PVAT showed higher EDR than controls. All EDR responses were blocked by L-NMMA and the expression of eNOS mRNA was increased in ApoE-/- PVAT (p = 0.035). CONCLUSION: Using a rat ApoE-/- model of early atherosclerosis, we capture a novel mechanism by which inflammatory PVAT compensates severe endothelial dysfunction by contributing NO upon cholinergic stimulation.

The (R)-enantiomer of the 6-chromanol derivate SUL-121 improves renal graft perfusion via antagonism of the α1-adrenoceptor.

SUL-compounds are protectants from cold-induced ischemia and mitochondrial dysfunction. We discovered that adding SUL-121 to renal grafts during warm machine reperfusion elicits a rapid improvement in perfusion parameters. Therefore, we investigate the molecular mechanisms of action in porcine intrarenal arteries (PIRA). Porcine kidneys were stored on ice overnight and perfusion parameters were recorded during treatment with SUL-compounds. Agonist-induced vasoconstriction was measured in isolated PIRA after pre-incubation with SUL-compounds. Receptor binding and calcium transients were assessed in α1-adrenoceptor (α1-AR) transgenic CHO cells. Molecular docking simulation was performed using Schrödinger software. Renal pressure during warm reperfusion was reduced by SUL-121 (-11.9 ± 2.50 mmHg) and its (R)-enantiomer SUL-150 (-13.2 ± 2.77 mmHg), but not by the (S)-enantiomer SUL-151 (-1.33 ± 1.26 mmHg). Additionally, SUL-150 improved renal flow (16.21 ± 1.71 mL/min to 21.94 ± 1.38 mL/min). SUL-121 and SUL-150 competitively inhibited PIRA contraction responses to phenylephrine, while other 6-chromanols were without effect. SUL-150 similarly inhibited phenylephrine-induced calcium influx and effectively displaced [7-Methoxy-3H]-prazosin in CHO cells. Docking simulation to the α1-AR revealed shared binding characteristics between prazosin and SUL-150. SUL-150 is a novel α1-AR antagonist with the potential to improve renal graft perfusion after hypothermic storage. In combination with previously reported protective effects, SUL-150 emerges as a novel protectant in organ transplantation.

The Novel Compound Sul-121 Preserves Endothelial Function and Inhibits Progression of Kidney Damage in Type 2 Diabetes Mellitus in Mice.

Diabetic nephropathy is still a common complication of type 2 diabetes mellitus (T2DM) and improvement of endothelial dysfunction (ED) and inhibition of reactive oxygen species (ROS) are considered important targets for new therapies. Recently, we developed a new class of compounds (Sul compounds) which inhibit mitochondrial ROS production. Here, we tested the therapeutic effects of Sul-121 on ED and kidney damage in experimental T2DM. Diabetic db/db and lean mice were implanted with osmotic pumps delivering Sul-121 (2.2 mg/kg/day) or vehicle from age 10 to 18 weeks. Albuminuria, blood pressure, endothelial mediated relaxation, renal histology, plasma creatinine, and H2O2 levels were assessed. Sul-121 prevented progression of albuminuria and attenuated kidney damage in db/db, as evidenced by lower glomerular fibronectin expression (~50%), decreased focal glomerular sclerosis score (~40%) and normalization of glomerular size and kidney weight. Further, Sul-121 restored endothelium mediated vasorelaxation through increased production of Nitric Oxide production and normalized plasma H2O2 levels. Sul-121 treatment in lean mice demonstrated no observable major side-effects, indicating that Sul-121 is well tolerated. Our data show that Sul-121 inhibits progression of diabetic kidney damage via a mechanism that involves restoration of endothelial function and attenuation of oxidative stress.

OS056. Angiotensin II sensitivity and endothelial dysfunction afterexperimental preeclampsia.

INTRODUCTION: Women who suffered from preeclampsia (PE) have an increased risk for cardiovascular and renal diseases later in life. Although the exact mechanisms underlying this relationship are unknown, they may relate to an increased sensitivity to angiotensin II (Ang-II) and endothelial dysfunction during a preeclamptic pregnancy, which may persist after PE. Recently, we showed vascular hypersensitivity to Ang-II and disturbed endothelial cell function in experimental PE in rats as compared to healthy pregnant rats. OBJECTIVES: To study whether vascular hypersensitivity to Ang-II and endothelial dysfunction persist postpartum in experimental PE. METHODS: In this ongoing study, we thus far included non-pregnant rats (NP;n=9), formerly healthy pregnant rats (HP;n=9) and formerly experimental preeclamptic rats (PE; infusion of a low dose endotoxin; n=16). Six weeks after pregnancy, animals from each group were treated with Ang-II (osmotic minipump; 200ng/kg/min;NP: n=5;HP: n=6;PE: n=8) or were sham treated (NP: n=4;HP: n=3;PE: n=8). Blood pressure was measured in all rats one day before and weekly after Ang-II or sham treatment (for three weeks). At termination, the aortas of sham operated rats were obtained. Aortic rings (2mm) were mounted for isotonic measurement of vasotonus. Endothelium-dependent acetylcholine- (ACh) mediated vasodilation was studied in phenylephrine-preconstricted rings in the presence of vehicle, N(G)-nitro-L-arginine methyl ester, indomethacin or both, followed by full concentration response curves for ACh (10(-8)M-10(-4)M). Ang-II sensitivity was assessed by obtaining full concentration response curves (10(-10)M-10(-6)M). AT-1 and AT-2 receptor sensitivity was determined by administration of Ang-II in the presence of the AT-1 receptor blocker losartan, or the AT-2 receptor blocker PD123319. RESULTS: Our results indicate no difference in mean (±SD) systolic blood pressure (SBP) between the three groups six weeks after delivery (NP: 129(±7);HP: 127(±9);PE: 123(±10)mmHg;p=0.248). However, after three weeks of Ang-II treatment, a trend was found towards a stronger increase in SBP in PE rats as compared to HP rats (45.7(±18.9)% vs 63.4(±20.1)% respectively;p=0.081). Although we found no differences in in-vitro Ang-II sensitivity between the three groups, NP rats showed a trend towards an increased sensitivity of the AT-2 receptor to Ang-II compared to both groups of formerly pregnant rats. Total ACh-mediated endothelial relaxation was not different between the three groups. However, contribution of both NO and EDHF components to ACh-mediated relaxation seemed decreased in both groups of formerly pregnant rats as compared to the NP rats. CONCLUSION: These preliminary data suggest that healthy rats that suffered from preeclampsia during pregnancy have increased in-vivo sensitivity to Ang-II postpartum as compared to rats with an uncomplicated pregnancy. Whether these differences are related to in-vitro- changes in Ang-II sensitivity or changes in endothelial function remains to be established.

Detection of cervical neoplasia by DNA methylation analysis in cervico-vaginal lavages, a feasibility study.

OBJECTIVE: To explore the feasibility of DNA methylation analysis for the detection of cervical neoplasia in self-obtained cervico-vaginal lavages. METHODS: Lavages collected by a self-sampling device and paired cervical scrapings were obtained from 20 cervical cancer patients and 23 patients referred with an abnormal cervical smear (15 with high-grade cervical intraepithelial neoplasia (CIN2+) and 8 without CIN). All lavages and scrapings were analyzed by liquid based cytology (LBC), Hybrid Capture II (HC-II) for hr-HPV DNA detection and by DNA methylation analysis (JAM3, TERT, EPB41L3 and C13ORF18). Concordance between lavages and scrapings was measured by Cohen's Kappa (k). RESULTS: In lavages and scrapings from cervical cancer patients (n=20), methylation analysis was positive in 19 (95%) and 19 (95%), HC-II in 16 (80%) and 15 (75%) and LBC in 15 (75%) and 19 (95%), respectively. In lavages and scrapings from CIN2+ patients (n=15), methylation analysis was positive in 10 (67%) and 12 (80%), HC-II in 15 (100%) and 15 (100%) and LBC in 11 (73%) and 12 (80%), respectively. Concordance between cervical scrapings and lavages (n=43) was for LBC k=0.522 (p<0.001), hr-HPV testing k=0.551 (p<0.001) and DNA methylation analysis k=0.653 (p<0.001). CONCLUSIONS: DNA methylation analysis in cervico-vaginal lavages obtained by a self-sampling device is feasible and its diagnostic performance appears to be at least comparable to the detection of cervical neoplasia by cytomorphology and hr-HPV. Our pilot study suggests that detection of cervical neoplasia by DNA methylation analysis in cervico-vaginal lavages warrants exploration of its use in large prospective studies.

α1-Adrenoceptor-mediated contraction of rat aorta is partly mediated via transactivation of the epidermal growth factor receptor.

BACKGROUND AND PURPOSE: High level of plasma catecholamines is a risk factor for vascular diseases such as hypertension and atherosclerosis. Catecholamines induce hypertrophy of vascular smooth muscle through α(1) -adrenoceptors, which in cell culture involves the transactivation of epidermal growth factor receptor (EGFR). We hypothesized that EGFR transactivation was also involved in contractions of rat aorta mediated by α(1) -adrenoceptors. EXPERIMENTAL APPROACH: Thoracic aorta was isolated from 12-14 week old male Wistar rats. In vitro aortic contractile responses to cumulative doses of phenylephrine were characterized in the absence and presence of the EGFR kinase inhibitors, AG1478 and DAPH, in intact and endothelium-denuded rings. Involvement of signal transduction pathways was investigated by using heparin and inhibitors of Src, matrix metalloproteinase (MMP), extracellular signal-regulated kinase (ERK)1/2 and phosphatidyl inositol 3-kinase (PI3K). Phosphorylation of EGFR and ERK1/2 was measured after short-term phenylephrine or EGF stimulation in aorta segments in the presence of AG1478 and the PI3K inhibitor, wortmannin. KEY RESULTS: AG1478 and DAPH concentration dependently attenuated phenylephrine-induced contractile responses in intact or endothelium-denuded aortic rings. Inhibition of PI3K (wortmannin and LY294002) but not heparin or inhibitors of Src or MMP, prevented the effect of AG1478 on the responses to phenylephrine. Phenylephrine induced phosphorylation of EGFR, which was partially blocked by AG1478. Phenylephrine also increased phosphorylation of ERK1/2, time-dependently and was blocked by AG1478 and wortmannin. CONCLUSIONS AND IMPLICATIONS: Contractions of rat thoracic aorta mediated by α(1) -adrenoceptors involved transactivation of EGFR, mediated via a PI3K and ERK1/2 dependent pathway.

Accuracy of a low priced liquid-based method for cervical cytology in 632 women referred for colposcopy after a positive Pap smear.

The aim of this quality controlling study was to determine the accuracy of liquid-based cytology (LBC) with the Turbitec cytocentrifuge technique. Cervical smears of 632 women, who were referred to our CIN outpatient department, after at least two smears with ASCUS or higher were evaluated and compared with the histological outcome. In 592 cases the smears revealed abnormalities of squamous epithelium, and in 40 cases the abnormalities of glandular epithelium. In the group of squamous epithelium abnormalities, the sensitivity for LSIL was 39.7% and the specificity was 89.2%; for the LSIL+ group, these values were 89.4% and 91.4%, respectively. For HSIL the sensitivity was 68.3% and the specificity 92.8%, for the HSIL+ group 82.3% and 92.3%, respectively. The ASCUS rate was low (2.4%). The Turbitec cytocentrifuge method was proved to be a very good LBC method for cervical smears. Because of a comparable accuracy together with a lower price, this LBC method outweighs commercial alternatives.

Angiotensin II type 2 receptor vasoactivity in internal mammary arteries of patients with coronary artery disease.

BACKGROUND: Several animal studies suggested that the angiotensin II type 2 (AT2) receptor subtype mediates vasodilation, yet the results in human arteries are less well described and more inconsistent. Therefore, we evaluated the role of the AT2 receptor stimulation on the vasotonus of human internal mammary arteries. METHODS: Internal mammary arteries were obtained from 50 patients undergoing coronary bypass surgery. The expression of angiotensin II type 1 (AT1) receptor and AT2 receptor mRNA was determined by using real-time polymerase chain reaction. In addition, angiotensin II and CGP42112A concentration-response curves (concentration range: 10(-10) M to 10(-6) M) were constructed in absence or presence of candesartan (10(-5) M) and/or the AT2 receptor-antagonist PD-123319 (10(-6) M) and/or the alpha receptor antagonist phentolamine. RESULTS: Both AT1 and AT2 receptor protein and mRNA were detected, and higher AT2 receptor mRNA expression levels were associated with increased contractile response to angiotensin II. Angiotensin II caused vasoconstriction up to 41.1 +/- 6.5% of the maximal response to phenylephrine, and PD123319 significantly reduced this response (28.6 +/- 9.6%, P < 0.001). Candesartan completely blocked the angiotensin II-mediated response (1.4 +/- 3.1%, P < 0.001 versus control), and additional blockade of the AT2 receptor with PD123319 did not change this effect (1.8 +/- 5.1%). Phentolamine (10(-5) M) caused attenuation and rightward shift of the angiotensin II concentration response curves. The AT2 receptor agonist CGP42112A did not induce a significant response. CONCLUSION: Although AT2 receptor mRNA is present in human internal mammary arteries, AT2 receptor stimulation does not mediate vasodilation in these arteries.

Disruption of endothelial caveolae is associated with impairment of both NO- as well as EDHF in acetylcholine-induced relaxation depending on their relative contribution in different vascular beds.

Caveolae represent an important structural element involved in endothelial signal-transduction. The present study was designed to investigate the role of caveolae in endothelium-dependent relaxation of different vascular beds. Caveolae were disrupted by cholesterol depletion with filipin (4x10(-6) g L(-1)) or methyl-beta-cyclodextrin (MCD; 1x10(-3) mol L(-1)) and the effect on endothelium-dependent relaxation was studied in rat aorta, small renal arteries and mesenteric arteries in the absence and presence of L-NMMA. The contribution of NO and EDHF, respectively, to total relaxation in response to acetylcholine (ACh) gradually changed from aorta (71.2+/-6.1% and 28.8+/-6.1%), to renal arteries (48.6+/-6.4% and 51.4+/-6.4%) and to mesenteric arteries (9.1+/-4.0% and 90.9+/-4.1%). Electron microscopy confirmed filipin to decrease the number of endothelial caveolae in all vessels studied. Incubation with filipin inhibited endothelium-dependent relaxation induced by cumulative doses of ACh (3x10(-9)-10(-4) mol L(-1)) in all three vascular beds. In aorta, treatment with either filipin or MCD only inhibited the NO component, whereas in renal artery both NO and EDHF formation were affected. In contrast, in mesenteric arteries, filipin treatment only reduced EDHF formation. Disruption of endothelial caveolae is associated with the impairment of both NO and EDHF in acetylcholine-induced relaxation.

Acetylcholine stimulated dilatation and stretch induced myogenic constriction in mesenteric artery of rats with chronic heart failure.

Rats with chronic heart failure (CHF) develop increased myogenic constriction in mesenteric resistance arteries. Here we investigated increased myogenic constriction in relation to alterations in EDHF- and NO-mediated dilatation in CHF-rats. Male Spraque-Dawley rats were subjected to myocardial-infarction or sham-surgery. At 9-10 weeks after surgery, isolated mesenteric artery ring preparations were studied in a wire-myograph. Stretch-induced myogenic constriction was obtained by stepwise increase of the internal circumference diameter (0.5-1.2 L100). Cyclooxygenase- and eNOS-inhibitors were employed to study NO- and EDHF-mediated dilatation in response to acetylcholine. Rats with CHF (n=8), but not sham-rats (n=6), developed significant myogenic constriction. In addition, the contribution of endothelial dilator mediators was significantly altered in CHF-rats, with increased dependency on NO and decreased EDHF-mediated dilatation. Moreover, EDHF-mediated dilatation was inversely correlated with myogenic constriction in individual CHF-rats (r=-0.74, p=0.04). These data demonstrate increased myogenic constriction in mesenteric arteries of rats with CHF post-MI to be correlated to decreased EDHF-mediated dilatation. These findings extend the previous observation that myogenic constriction antagonizes EDHF-mediated dilatation in rat coronary artery under normal conditions, and suggests this relationship also to become functional in mesenteric arteries under pathophysiological conditions of CHF.

Myogenic constriction is increased in mesenteric resistance arteries from rats with chronic heart failure: instantaneous counteraction by acute AT1 receptor blockade.

(1) Increased vascular resistance in chronic heart failure (CHF) has been attributed to stimulated neurohumoral systems. However, local mechanisms may also importantly contribute to set arterial tone. Our aim, therefore, was to test whether pressure-induced myogenic constriction of resistance arteries in vitro--devoid of acute effects of circulating factors--is increased in CHF and to explore underlying mechanisms. (2) At 12 weeks after coronary ligation-induced myocardial infarction or SHAM-operations in rats, we studied isolated mesenteric arteries for myogenic constriction, determined as the active constriction (% of passive diameter) in response to stepwise increase in intraluminal pressure (20 - 160 mmHg), in the absence and presence of inhibitors of potentially involved modulators of myogenic constriction. (3) We found that myogenic constriction in mesenteric arteries from CHF rats was markedly increased compared to SHAM over the whole pressure range, the difference being most pronounced at 60 mmHg (24+/-2 versus 4+/-3%, respectively, P<0.001). (4) Both removal of the endothelium as well as inhibition of NO production (L-N(G)-monomethylarginine, 100 micro M) significantly increased myogenic constriction (+16 and +25%, respectively), the increase being similar in CHF- and SHAM-arteries (P=NS). Neither endothelin type A (ET(A))-receptor blockade (BQ123, 1 micro M) nor inhibition of perivascular (sympathetic) nerve conduction (tetrodotoxin, 100 nM) affected the myogenic response in either group. (5) Interestingly, increased myogenic constriction in CHF was fully reversed after angiotensin II type I (AT(1))-receptor blockade (candesartan, 100 nM; losartan, 10 micro M), which was without effect in SHAM. In contrast, neither angiotensin-converting enzyme (ACE) inhibition (lisinopril, 1 micro M; captopril, 10 micro M) or AT(2)-receptor blockade (PD123319, 1 micro M), nor inhibition of superoxide production (superoxide dismutase, 50 U ml(-1)), TXA(2)-receptor blockade (SQ29,548, 1 micro M) or inhibition of cyclooxygenase-derived prostaglandins (indomethacin, 10 micro M) affected myogenic constriction. (6) Sensitivity of mesenteric arteries to angiotensin II (10 nM - 100 micro M) was increased (P<0.05) in CHF (pD(2) 7.1+/-0.4) compared to SHAM (pD(2) 6.2+/-0.3), while the sensitivity to KCl and phenylephrine was not different. (7) Our results demonstrate increased myogenic constriction in small mesenteric arteries of rats with CHF, potentially making it an important target for therapy in counteracting increased vascular resistance in CHF. Our results further suggest active and instantaneous participation of AT(1)-receptors in increased myogenic constriction in CHF, involving increased sensitivity of AT(1)-receptors rather than apparent ACE-mediated local angiotensin II production.

Recombinant Semliki Forest virus as a vector system for fast and selective in vivo gene delivery into balloon-injured rat aorta.

Previously, we demonstrated that recombinant Semliki Forest virus (SFV) vector rapidly and selectively transfers genes into cultured vascular smooth muscle cells (VSMC), leaving endothelial cells (EC) unaffected. From this, we hypothesized that recombinant SFV in vivo only transfers genes into the media of balloon-injured but not intact vessel, that gene expression in VSMC is fast, and that the specificity of SFV for VSMC is caused by specific binding sites. To address these hypotheses, we studied the time course of in vivo SFV-LacZ and Ad-LacZ expression in balloon-injured rat aorta. In addition, the fusion characteristics of fluorescent pyrene-labeled SFV were explored in cultured VSMC and EC. In intact aorta, no LacZ expression was found in the intima or media at 24 h. In contrast, in denuded aorta, LacZ expression was detected in as early as 12 h after incubation. LacZ expression was predominantly present in the media. Ad-LacZ expression started after 12 h, but was predominantly present in the adventitia. Ad-LacZ expression in the media started after 72 h. In vitro transfection with SFV showed that fusion was higher and, moreover, saturable in VSMC as compared with EC, indicating the presence of specific SFV binding sites on VSMC, but not EC. From this we conclude that in vivo selectivity of SFV in balloon-injured vessels is based on the removal of the endothelium, which results in accessibility of VSMC in the media that carry specific binding sites for the SFV vector.

Overexpression of the human angiotensin II type 1 receptor in the rat heart augments load induced cardiac hypertrophy.

Angiotensin II is known to stimulate cardiac hypertrophy and contractility. Most angiotensin II effects are mediated via membrane bound AT1 receptors. However, the role of myocardial AT1 receptors in cardiac hypertrophy and contractility is still rarely defined. To address the hypothesis that increased myocardial AT1 receptor density causes cardiac hypertrophy apart from high blood pressure we developed a transgenic rat model which expresses the human AT1 receptor under the control of the alpha-myosin heavy-chain promoter specifically in the myocardium. Expression was identified and quantified by northern blot analysis and radioligand binding assays, demonstrating overexpression of angiotensin II receptors in the transgenic rats up to 46 times the amount seen in nontransgenic rats. Coupling of the human AT1 receptor to rat G proteins and signal transduction cascade was verified by sensitivity to GTP-gamma-S and increased sensitivity of intracellular Ca2+ [Ca2+]i to angiotensin II in fluo-3 loaded transgenic cardiomyocytes. Transgenic rats exhibited normal cardiac growth and function under baseline conditions. Pronounced hypertrophic growth and contractile responses to angiotensin II, however, were noted in transgenic rats challenged by volume and pressure overload. In summary, we generated a new transgenic rat model that exhibits an upregulated myocardial AT1 receptor density and demonstrates augmented cardiac hypertrophy and contractile response to angiotensin II after volume and pressure overload, but not under baseline conditions.

Preservation of endothelial integrity and function in experimental vascular anastomosis with non-penetrating clips.

BACKGROUND: Vascular repair with sutures is associated with disruption of the endothelial lining and subsequent thrombus formation on the intraluminal lesions. This experimental study was designed to determine whether the use of non-penetrating clips improved endothelial preservation. METHODS: In ten female pigs, 25-mm arteriotomies were made in both carotid arteries. The arteriotomies were repaired with jugular vein patches. On the left side, the repair was done with 1.4-mm titanium clips, and on the right side with two running 6/0 polypropylene sutures. Next, the aorta was divided and subsequently repaired with 2-mm clips in five of these pigs, and with two running 5/0 polypropylene sutures in the remaining five pigs. Endothelial function was studied at the anastomotic site in the carotid arteries by determination of endothelium-dependent and -independent relaxatory responses. Morphometric examination of the carotid arteries and inspection of the aortic endothelium were performed by means of scanning electron microscopy. RESULTS: Maximal endothelium-dependent relaxation to adenosine 5'-diphosphate was less in sutured than in clipped carotid arteries (P < 0.05), while there was no difference in maximal endothelium-independent relaxation to sodium nitrite. This result in clipped carotid arteries was not accompanied by less intimal hyperplasia. Screening of the aortic anastomotic line showed better preservation of endothelial architecture after clip anastomosis. Mean cross-clamp time for carotid patch repair was significantly less when using clips than with sutures. CONCLUSION: The use of non-penetrating clips for vascular anastomoses preserved endothelial function and structural integrity better than running sutures, although the degree of intimal hyperplasia was similar.

Does a low-salt diet exert a protective effect on endothelial function in normal rats?

Sodium restriction is often used as an adjunct in the treatment of conditions characterized by endothelial dysfunction, such as hypertension and heart or kidney disease. However, the effect of sodium restriction on endothelial function is not known. Therefore, male Wistar rats were studied after a fixed salt diet had been maintained (low-salt group: 0.05% NaCl, n = 10; normal-salt group: 0.3% NaCl, n = 10) for 6 weeks. Blood pressure and sodium excretion values were measured once a week. Subsequently the rats were killed, the aorta was removed, and rings were cut. Endothelium-independent (sodium nitrite [SN]) and endothelium-dependent (acetylcholine [ACh]) vasodilator responses were assessed in the presence of indomethacin (a cyclo-oxygenase inhibitor) and in the presence or absence of NG-monomethyl-L-arginine (L-NMMA; a competitive inhibitor of nitric oxide [NO] synthase). Endothelium-independent vasodilatation was not different for the two salt groups. Endothelium-dependent vasodilatation, on the other hand, was different. The response to ACh was almost completely abolished by L-NMMA in the normal-salt group, whereas vasodilatation was partially preserved during L-NMMA in the low-salt group. Accordingly, the L-NMMA-sensitive contribution to ACh-dependent vasodilatation was smaller in the low-salt group. Thus, salt restriction induced a non-NO and non-prostaglandin-dependent vasodilating pathway. By exclusion this could be endothelium-derived hyperpolarizing factor, a pathway of vasculoprotective potential. Accordingly, the relative contributions of the different vasoactive endothelial pathways were affected by salt intake. Further research will be needed to clarify the nature and importance of this non-NO, non-prostaglandin-dependent pathway in the clinical setting as well.

Effects of quinapril on clinical outcome after coronary artery bypass grafting (The QUO VADIS Study). QUinapril on Vascular Ace and Determinants of Ischemia.

The QUO VADIS study was designed to explore whether 1 year of angiotensin-converting enzyme inhibition with quinapril (40 mg/day) would decrease ischemia in patients who underwent coronary artery bypass grafting (CABG). Patients (n = 149) scheduled for CABG were randomized 4 weeks before surgery. Study medication was used from randomization up to 1 year after CABG. Exercise testing was performed at randomization; the exercise test was repeated 1 year after CABG and patients underwent 48-hour Holter monitoring. Clinical ischemic events were recorded and defined as death, revascularization, myocardial infarction, recurrence of angina pectoris, ischemic stroke, or transient ischemic attack. Baseline characteristics were similar between groups. Total exercise time increased overall by 75 +/- 76 seconds 1 year after CABG (placebo +79 +/- 75 seconds, quinapril +72 +/- 79 seconds, p = 0.6). All patients had ischemic ST-segment changes at randomization; 33% of patients had ischemic ST-segment changes 1 year after CABG (placebo 29%, quinapril 37%, p = 0.4). On Holter monitoring, the number of patients experiencing > or = 1 episodes of ischemia was equal in both groups. Treatment with quinapril significantly reduced clinical ischemic events after CABG: 15% in patients on placebo versus 4% of patients on quinapril (hazard ratio 0.23, 95% confidence interval 0.06 to 0.87, p = 0.02). Long-term quinapril treatment significantly reduced clinical ischemic events within 1 year after CABG, although ischemia at exercise testing and Holter monitoring was unchanged.

Increased kallikrein expression protects against cardiac ischemia.

Multiple indirect lines of evidence point at a cardioprotective role for enhanced bradykinin formation. In particular, the inhibition of angiotensin-converting enzyme, also known as kininase II, can protect against cardiac ischemia, putatively via accumulation of bradykinin. To address whether an increase in kinin formation is sufficient to protect against cardiac ischemia, we studied transgenic rats harboring the human tissue kallikrein gene TGR(hKLK1) under the control of the metallothionein promoter, which drives expression of the transgene in various organs including the heart. We subjected the isolated hearts from transgenic rats and their transgene negative littermates to ex vivo regional cardiac ischemia and reperfusion. During the experiment, the hearts were treated with either vehicle or the specific bradykinin type 2 receptor antagonist HOE 140 (10-9 M). In the transgenic rats, overflow of nucleotide breakdown products upon reperfusion was significantly less (455 +-54 nmol/min/g in transgene negative rats vs. 270+-57 nmol/min/g in the transgenic rats, P.

Comparison of zofenopril and lisinopril to study the role of the sulfhydryl-group in improvement of endothelial dysfunction with ACE-inhibitors in experimental heart failure.

We evaluated the role of SH-groups in improvement of endothelial dysfunction with ACE-inhibitors in experimental heart failure. To this end, we compared the vasoprotective effect of chronic treatment with zofenopril (plus SH-group) versus lisinopril (no SH-group), or N-acetylcysteine (only SH-group) in myocardial infarcted (MI) heart failure rats. After 11 weeks of treatment, aortas were obtained and studied as ring preparations for endothelium-dependent and -independent dilatation in continuous presence of indomethacin to avoid interference of vasoactive prostanoids, and the selective presence of the NOS-inhibitor L-NMMA to determine NO-contribution. Total dilatation after receptor-dependent stimulation with acetylcholine (ACh) was attenuated (-49%, P<0.05) in untreated MI (n=11), compared to control rats with no-MI (n=8). This was in part due to impaired NO-contribution in MI (-50%, P<0.05 versus no-MI). At the same time the capacity for generation of biologically active NO after receptor-independent stimulation with A23187 remained intact. Chronic treatment with n-acetylcysteine (n=8) selectively restored NO-contribution in total dilatation to ACh. In contrast, both ACE-inhibitors fully normalized total dilatation to ACh, including the part mediated by NO (no significant differences between zofenopril (n=10) and lisinopril (n=8)). Zofenopril, but not lisinopril, additionally potentiated the effect of endogenous NO after A23187-induced release from the endothelium (+100%) as well as that of exogenous NO provided by nitroglycerin (+22%) and sodium nitrite (+36%) (for all P<0.05 versus no-MI). We conclude that ACE-inhibition with a SH-group has a potential advantage in improvement of endothelial dysfunction through increased activity of NO after release from the endothelium into the vessel wall. Furthermore, this is the first study demonstrating the selective normalizing effect of N-actylcysteine on NO-contribution to ACh-induced dilatation in experimental heart failure.

Direct vasodilating effects of the new dopaminergic agonist Z1046 in human arteries.

Dopaminergic agonists remain of interest in the treatment of heart failure; however, concomitant stimulation of alpha- and beta-receptors should be avoided. This study evaluates the dopaminergic and adrenergic (vasodilating) properties of Z1046, epinine (the active metabolite of ibopamine), and dopamine. Isotonic contraction experiments were performed on human internal mammary artery rings in vitro. alpha1-Antagonistic effects of Z1046 were demonstrated by performing cumulative dose-response curves with the selective alpha1-agonist phenylephrine in the presence of Z1046. Furthermore, both alpha1- and dopamine-mediated receptor effects of Z1046, epinine, and dopamine were studied by performing cumulative dose-response relations both at baseline and in precontracted artery rings both with and without the D1-like antagonist SCH23390. In contrast to both epinine and dopamine, Z1046 is devoid of alpha1-receptor-mediated contraction. Furthermore, Z1046, epinine, and dopamine induced direct dopamine receptor-mediated vasodilation when interfering alpha1 effects were blocked. In contrast to epinine and dopamine, Z1046 is devoid of vasoconstricting properties at higher dosages. Because of its D1-like agonistic and alpha1-antagonistic properties, Z1046 is an effective vasodilator in the whole dosage range. Because of its total receptor profile, Z1046 appears to be more favorable for treatment of heart failure than is ibopamine.

Angiotensin II formation in human vasculature after chronic ACE inhibition: a prospective, randomized, placebo-controlled study. QUO VADIS Investigators.

The QUO VADIS (the effects of QUinapril On Vascular Ace and Determinants of ISchemia) study was a randomized, double-blind, placebo-controlled trial designed to evaluate the effects of long-term angiotensin-converting enzyme (ACE) inhibition on angiotensin II formation in human vasculature. Patients (n = 187) scheduled for coronary artery bypass surgery used study medication 27 +/- 1 days before surgery. Segments of internal mammary arteries were exposed to increasing doses (0.1 nM-1 microM) of angiotensin I and II in organ baths. The rate of local angiotensin II formation is a function of the reciprocal of the difference between the pEC50's of the dose response curves to angiotensin I and II (-log/mol) and of the area between the curves (units). Quinapril (40 mg) and captopril (3 x 50 mg) similarly and significantly reduced mean blood pressure compared with placebo (p = 0.04). Difference between pEC50's was 0.90 +/- 0.08 in quinapril patients compared with 0.60 +/- 0.08 for placebo (p = 0.01); the area between curves was 91 +/- 8 for quinapril patients compared with 67 +/- 8 for placebo (p = 0.03). Angiotensin II formation was decreased to a lesser extent with captopril and was not statistically different from placebo (p = 0.3); the difference between pEC50's was 0.83 +/- 0.15; the area between curves was 84 +/- 12. This is the first randomized study to demonstrate that long-term oral treatment with an ACE inhibitor reduces vascular angiotensin II formation in humans.