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1.
Chinese journal of integrative medicine ; (12): 448-454, 2018.
Article in English | WPRIM | ID: wpr-687928

ABSTRACT

<p><b>OBJECTIVE</b>To investigate whether the methanol extract of Berberis amurensis Rupr. (BAR) augments penile erection using in vitro and in vivo experiments.</p><p><b>METHODS</b>The ex vivo study used corpus cavernosum strips prepared from adult male New Zealand White rabbits. In in vivo studies for intracavernous pressure (ICP), blood pressure, mean arterial pressure (MAP), and increase of peak ICP were continuously monitored during electrical stimulation of Sprague-Dawley rats.</p><p><b>RESULTS</b>Preconstricted with phenylephrine (PE) in isolated endotheliumintact rabbit corus cavernosum, BAR relaxed penile smooth muscle in a dose-dependent manner, which was inhibited by pretreatment with NG-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase inhibitor, and H-[1,2,4]-oxadiazole-[4,3-α]-quinoxalin-1-one, a soluble guanylyl cclase inhibitor. BAR significantly relaxed penile smooth muscles dose-dependently in ex vivo, and this was inhibited by pretreatment with L-NAME H-[1,2,4]-oxadiazole-[4,3-α]-quinoxalin-1-one. BAR-induced relaxation was significantly attenuated by pretreatment with tetraethylammonium (TEA, P<0.01), a nonselective K channel blocker, 4-aminopyridine (4-AP, P<0.01), a voltage-dependent K channel blocker, and charybdotoxin (P<0.01), a large and intermediate conductance Ca sensitive-K channel blocker, respectively. BAR induced an increase in peak ICP, ICP/MAP ratio and area under the curve dose dependently.</p><p><b>CONCLUSION</b>BAR augments penile erection via the nitric oxide/cyclic guanosine monophosphate system and Ca sensitive-K (BK and IK) channels in the corpus cavernosum.</p>


Subject(s)
Animals , Male , Rabbits , Area Under Curve , Berberis , Chemistry , Blood Pressure , Cyclic GMP , Metabolism , Epoprostenol , Pharmacology , In Vitro Techniques , Indomethacin , Pharmacology , Models, Biological , Muscle Relaxation , Muscle, Smooth , Physiology , NG-Nitroarginine Methyl Ester , Pharmacology , Nitric Oxide , Metabolism , Penile Erection , Phenylephrine , Pharmacology , Plant Extracts , Pharmacology , Potassium Channel Blockers , Pharmacology , Potassium Channels , Metabolism , Pressure
2.
The Korean Journal of Physiology and Pharmacology ; : 175-182, 2007.
Article in English | WPRIM | ID: wpr-728210

ABSTRACT

Members of prostaglandin (PG) E-series elicit cellular effects mainly through adenylyl cyclase-cAMP signaling. The role of PGE2-induced increase in cAMP has been shown to be compartmentalized in the cardiac myocytes: PGE2-induced increase of cAMP is not involved in the control of cardiomyocytic contraction. The purpose of the present study was to define the effect of PGE1 on the cGMP levels and the role of PGE1 in the atrial secretory function. Experiments were performed in perfused beating rabbit atria and atrial contractile responses, cGMP and cAMP efflux, and atrial natriuretic peptide (ANP) secretion were measured. PGE1 increased cGMP as well as cAMP efflux concentration in a concentration-dependent manner, however, no significant changes in atrial secretory responses were observed (with 1.0microM PGE1; for cGMP, 144.76+/-37.5%, n=11 versus -16.81+/-4.76%, n=6, control, p<0.01; for cAMP, 187.60+/-41.52%, n=11 versus 7.38+/-19.44%, n=6, control, p<0.01). PGE1 decreased atrial dynamics slightly but transiently, whereas PGE2 showed similar effects but with lower potency. Isoproterenol increased atrial cAMP efflux (with 2.0 nM; 145.71+/-41.89, n=5 versus 7.38+/-19.44%, n=6, control, p<0.05) and mechanical dynamics and decreased ANP secretion. The PGE1-induced increase in cGMP efflux showed a bell-shaped concentration-response curve. PGE1-induced increase of cGMP efflux was not observed in the presence of L-NAME, an inhibitor of nitric oxide (NO) synthase, or ODQ, an inhibitor of NO-sensitive guanylyl cyclase. L-NAME and ODQ showed no significant effect on the PGE1-induced transient decrease of atrial dynamics. These data indicate that PGE1 increases cGMP levels via NO-soluble GC signaling in the cardiac atrium and also show that PGE1-induced increases in cGMP and cAMP levels are not involved in the regulation of atrial secretory and contractile functions.


Subject(s)
Alprostadil , Atrial Function , Atrial Natriuretic Factor , Dinoprostone , Guanylate Cyclase , Isoproterenol , Myocytes, Cardiac , NG-Nitroarginine Methyl Ester , Nitric Oxide , Nucleotides, Cyclic
3.
The Korean Journal of Physiology and Pharmacology ; : 149-154, 2006.
Article in English | WPRIM | ID: wpr-728565

ABSTRACT

Selective inhibition of phosphodiesterase (PDE) 5 opened a new therapeutic approach for cardiovascular disorders. Therefore, the effect of PDE5 inhibition on the cardiac function should thoroughly be defined. The purpose of the present study was to define the effects of sildenafil, a selective inhibitor of PDE5, on the atrial cGMP efflux, atrial dynamics, and the release of atrial natriuretic peptide (ANP). By perfusing rabbit left atria to allow atrial pacing, changes in atrial stroke volume and pulse pressure, transmural extracellular fluid translocation, cGMP efflux, and ANP secretion were measured. SIN-1, an NO donor and soluble (s) guanylyl cyclase (GC) activator, and C-type natriuretic peptide (CNP), an activator of particulate (p) GC activator, were used. Sildenafil increased basal levels of cGMP efflux slightly but not significantly. Sildenafil in a therapeutic dose increased atrial dynamics (for atrial stroke volume, 2.84+/-1.71%, n=12, vs -0.71+/-0.86%, n=21; p<0.05) and decreased ANP release (-9.02+/-3.36%, n=14, vs 1.35+/-3.25%, n=23; p<0.05), however, it had no effect on the SIN-1- or CNP-induced increase of cGMP levels. Furthermore, sildenafil in a therapeutic dose accentuated SIN-1-induced, but not CNP-induced, decrease of atrial pulse pressure and ANP release. These data indicate that PDE5 inhibition with sildenafil has a minor effect on cGMP levels, but has a distinct effect on pGC-cGMP- and sGC-cGMP-induced contractile and secretory function.


Subject(s)
Humans , Atrial Natriuretic Factor , Blood Pressure , Cyclic Nucleotide Phosphodiesterases, Type 5 , Extracellular Fluid , Guanylate Cyclase , Natriuretic Peptide, C-Type , Stroke Volume , Tissue Donors , Sildenafil Citrate
4.
The Korean Journal of Physiology and Pharmacology ; : 87-94, 2005.
Article in English | WPRIM | ID: wpr-727665

ABSTRACT

It is not clear whether Ca2+-induced Ca2+ release from the sarcoplasmic reticulum (SR) is involved in the regulation of atrial natriuretic peptide (ANP) release. Previously, we have shown that nifedipine increased ANP release, indicating that Ca2+ entry via voltage-gated L-type Ca2+ channel activation decreases ANP release. The purpose of the present study was two-fold: to define the role of SR Ca2+ release in the regulation of ANP release and whether Ca2+ entry via L-type Ca2+ channel is prerequisite for the SR-related effect on ANP release. Experiments were performed in perfused beating rabbit atria. Ryanodine, an inhibitor of SR Ca2+ release, increased atrial myocytic ANP release (8.69+/-3.05, 19.55+/-1.09, 27.31+/-3.51, and 18.91+/-4.76% for 1, 2, 3, and 6microM ryanodine, respectively; all P< 1) with concomitant decrease in atrial stroke volume and pulse pressure in a dose-dependent manner. In the presence of thapsigargin, an inhibitor of SR Ca2+ pump, ryanodine-induced increase in ANP release was not observed. Thapsigargin attenuated ryanodine-induced decrease in atrial dynamic changes. Blockade of L-type Ca2+ channel with nifedipine abolished ryanodine-induced increase in ANP release (0.69+/-5.58% vs. 27.31+/-3.51%; P< 0.001). In the presence of thapsigargin and ryanodine, nifedipine increased ANP release and decreased atrial dynamics. These data suggest that Ca2+-induced Ca2+ release from the SR is inversely involved in the regulation of atrial myocytic ANP release.


Subject(s)
Atrial Natriuretic Factor , Blood Pressure , Nifedipine , Ryanodine , Sarcoplasmic Reticulum , Stroke Volume , Thapsigargin
5.
Korean Journal of Nephrology ; : 53-62, 2003.
Article in Korean | WPRIM | ID: wpr-12018

ABSTRACT

BACKGROUND: K+ channel opener has been considered as a vasorelaxing agent working through hyperpolarization of vascular smooth muscle cells. Renal tubules-proximal, thick ascending limb of Henle and cortical collecting duct-are the site of the diversity of the K+ channel. ATP-sensitive K+ channel has been observed in the apical membranes of the thick ascending limb of Henle and collecting duct, and basolateral membrane of the proximal tubule. It was also shown that K+ channel opener increased renal hemodynamics and elicited diuretic and natriuretic effects. METHODS: To clarify the renal effects of WAY120491, a K+ channel opener, experiments were performed in unanesthetized normotensive and renal hypertensive rabbits allowing unilateral renal arterial infusion of agent. RESULTS: Intrarenal arterial infusion (0.13, 0.32 and 0.64 microgram/kg/min) of WAY120491 increaased CPAH, CCr, urine volume, UNaV, UKV and CH2O. Renal hemodynamic effects and increments of urine volume and free water clearance were completely blocked by glibenclamide (8.2 g/kg/min), while increments of UNaV and FENa were not significantly affected. Renal hemodynamic and tubular effects of WAY120491 were not significantly different in two-kidney one clip Goldblatt hypertensive rabbits from sham-operated rabbits. CONCLUSIONS: These results suggest that WAY120491 elicits renal effects through ATP-sensitive K+ channel in the renal vasculatures and renal tubules and the renal effects of WAT120491 may not be altered in the hypertension.


Subject(s)
Rabbits , Diuresis , Extremities , Glyburide , Hemodynamics , Hypertension , Membranes , Muscle, Smooth, Vascular , Natriuresis , Natriuretic Agents , Water
6.
Korean Journal of Nephrology ; : 55-66, 2002.
Article in Korean | WPRIM | ID: wpr-126477

ABSTRACT

BACKGROUND: Atrial cardiomyocytes synthesize, store and release atrial natriuretic peptide(ANP) which has potent physiological effects, including natriuresis, diuresis, relaxation of vascular smooth muscle and inhibition of aldosterone and renin secretion. A family of atrial peptides are derived from a precursor proANP. However, the structure-activity relationship of several C-terminal ANPs are not yet well documented. METHODS: The effects of structural difference of ANP analogs on the renal function were studied with a sensitive and reproducible bioassay using intrarenal arterial infusion in unanesthetized rabbits. RESULTS: Rat ANP-(1-28)(rANP, 12-Ile), a-human ANP-(1-28)(hANP, 12-Met), atriopeptin III [APIII, rANP-(5-28)], atriopeptin II[APII, rANP-(5- 27)], atriopeptin I[API, rANP-(5-25)], a-human ANP- (7-28)[hANP-(7-28)], and ANP fragments(13-28) [ANP-(13-28)] and (17-28)[ANP-(17-28)] were infused into left renal artery. No significant differences were observed between rANP and hANP. Diuretic and natriuretic activities of APIII were significantly lower than those of rANP and hANP, but were similar to those of hANP-(7-28). Diuretic and natriuretic effects of APII were similar to rANP and hANP in terms of peak responses. Duration of the effects of APII were longer than those of rANP and hANP. No significant changes were observed by infusions of API, and ANP fragments, ANP-(13-28) and ANP-(17-28). rANP, hANP and APIII decreased active but increased inactive renin secretion. CONCLUSION: These data suggest that substitution of isoleucine to methionine at 12 position of ANP does not affect the renal effects of ANP and that disulfide bond and C-terminal segment of ANP are important for the possession of natriuretic and diuretic activities.


Subject(s)
Animals , Humans , Rabbits , Rats , Aldosterone , Atrial Natriuretic Factor , Biological Assay , Diuresis , Isoleucine , Methionine , Muscle, Smooth, Vascular , Myocytes, Cardiac , Natriuresis , Natriuretic Agents , Peptides , Relaxation , Renal Artery , Renin , Structure-Activity Relationship
7.
Korean Journal of Nephrology ; : 737-748, 2001.
Article in Korean | WPRIM | ID: wpr-227469

ABSTRACT

No abstract available.

8.
Korean Journal of Nephrology ; : 851-862, 2001.
Article in Korean | WPRIM | ID: wpr-227456

ABSTRACT

Roles of the nonclipped kidney in the development and maintenance of the high blood pressure in two- kidney, one clip hypertension remain to be defined. It has been known that the pathophysiology of hypertension is different by the presence or absence of the contralateral kidney in renal hypertension. The present study was undertaken to evaluate the effects of intrarenal norepinephrine in the nonclipped kidney exposed to the high blood pressure. Experiments were performed in 7-day two-kidney, one clip Goldblatt hypertensive and sham-operated normotensive rabbits. The basal levels of renal plasma flow and urine flow, and urinary excretion of electrolytes were higher in the nonclipped kidney of two-kidney, one clip Goldblatt hypertensive than in the corresponding kidney of sham-operated normotensive rabbits. Intrarenal infusion of norepinephrine increased renal perfusion resistance, and decreased renal hemodynamics and renal excretory function in a dose-dependent manner in both hypertensive and normotensive rabbits. The renal hemodynamics and excretory responses to intrarenal norepinephrine infusion were attenuated in two-kidney, one clip Goldblatt hypertensive rabbits. The changes by norepinephrine infusion of the renal excretory function were closely correlated with those in glomerular filtration rate or renal plasma flow. These results suggest that the impaired vascular reactivity in the nonclipped kidney is one of the early changes appeared in the course of multifactorial derangements in renal hypertension and that the impairment may be an adaptive response of the kidney to high blood pressure.


Subject(s)
Rabbits , Animals
9.
Korean Journal of Nephrology ; : 872-881, 2001.
Article in Korean | WPRIM | ID: wpr-102801

ABSTRACT

No abstract available.


Subject(s)
Rabbits , Animals
10.
Korean Journal of Urology ; : 159-165, 2001.
Article in Korean | WPRIM | ID: wpr-184767

ABSTRACT

PURPOSE: Relaxation of the penile cavernosum smooth muscle is a critical event in erection. Artemisia iwaymogi(AI) is a perennial herb growing in Korea. The aerial parts have been used in folk medicine. Bioassay-guided fractionation of an H2O extract of AI has furnished an inhibitory substance (PCLS-2). We investigated compound extracted in the rabbit corporal cavernosum smooth muscle. MATERIALS AND METHODS: Bioassay-guided fractionation of an H2O extract was used. A strip of rabbit corpus cavernosum was mounted in an organ chamber to measure the isometric tension. PCLS-2 compound induced relaxations were evaluated by in vitro study using muscarinic receptor blocker atropine (ATR), cyclo-oxygenase inhibitor indomethacin, nitric oxide synthase (NOS) ihibitor Nitro-L Arginine-Methyl Ester (NAME), guanylate cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin 1-one (ODQ), intrinsic neurotransmission inhibitor tetrodotoxin (TTX), or/and potassium channel blockers. RESULTS: PCLS-2 showed relaxation in a dose-dependent manner. Atropine, Indomethacin, NAME, ODQ, TTX, glibenclamide, tetraethylammonium, 4-aminopyridine, charybdotoxin, or apamin did not inhibit the relaxation induced by PCLS-2 compound. CONCLUSIONS: The present results suggest that the PCL-2 compound has effect of relaxation of corpus cavernosum smooth muscle and the relaxation was not involved muscarinic receptor, nitric oxide, prostaglandin, potassium channels and intrinsic neurotransmission. Other mechanisms may by involved in the PCLS-2 induced relaxation in the rabbit corpus cavernosum smooth muscle.


Subject(s)
4-Aminopyridine , Apamin , Artemisia , Atropine , Charybdotoxin , Glyburide , Guanylate Cyclase , Indomethacin , Korea , Medicine, Traditional , Muscle, Smooth , Nitric Oxide , Nitric Oxide Synthase , Potassium Channel Blockers , Potassium Channels , Prostaglandin-Endoperoxide Synthases , Receptors, Muscarinic , Relaxation , Synaptic Transmission , Tetraethylammonium , Tetrodotoxin
11.
Korean Journal of Nephrology ; : 624-636, 2000.
Article in Korean | WPRIM | ID: wpr-73562

ABSTRACT

It has been suggested that arginine vasopressin is involved in the acute, but not chronic, regulation of blood pressure. It is still debatable on the role of arginine vasopressin in the development and maintenance of high blood pressure, especially in renal hypertension. This study was performed to examine antidiuretic and renal hemodynamic effects of extremely low doses of arginine vasopressin and the modification of the effects in the early phase of two-kidney one clip Goldblatt hypertensive rabbits. Very low doses(up to 10-20mole/kg/min) of intrarenal arginine vasopressin induced decreases in urine volume, free water clearance, glomerular filteration rate and renal plasma flow(CPAH). The renal effects of arginine vasopressin were dose-dependent. These data indicate that the sensitivity of the kidney to decrease urine volume in response to arginine vasopressin is at least three orders of magnitude higher than previously reported. The renal effects of arginine vasopressin was significantly attenuated by the pretreatment of V2-receptor antagonist. The antidiuretic and renal hemodynamic effects elicited by very low doses of intrarenal arginine vasopressin were suppressed in the contralateral unclipped kidney of two-kidney, one clip Goldblatt hypertensive rabbits. These data suggest that the renal functions can be regulated normally by an extremely low concentration of plasma arginine vasopressin and the regulatory mechanism controlled by the ultralow plasma levels of arginine vasopressin is suppressed in the early phase of two-kidney, one clip Goldblatt hypertension.


Subject(s)
Rabbits , Arginine Vasopressin , Arginine , Blood Pressure , Hemodynamics , Hypertension , Hypertension, Renal , Hypertension, Renovascular , Kidney , Plasma , Water
12.
Korean Journal of Nephrology ; : 637-648, 2000.
Article in Korean | WPRIM | ID: wpr-73561

ABSTRACT

Arginine vasopressin(AVP) released from the posterior pituitary gland is well known to cause an increase in blood pressure, antidiuresis, natriuresis and inhibition of renin secretion. However, the mechanism involved in AVP-induced natriuresis is still unknown. To investigate the mechanism of AVP- induced natriuresis, different doses of AVP were infused into the left renal artery for 10 min and renal function and data were obtained in unanesthetized rabbits. Infusion of different doses of AVP (0.3pg/kg/min-10,000pg/kg/min) caused marked decreases in urine volume, renal blood flow, glomerular filtration rate and free water clearance without changes in blood pressure. Changes in renal function by AVP were not dose-dependent but it took more time for the renal function to recover with increasing doses. Infusion of large doses of AVP(3,000, 10,000pg/kg/min) caused increases in sodium excretion in both kidneys without changes in blood pressure. Infusion of AVP caused a decrease in renin secretion rate. In indomethacin-treated rabbits, changes in urine volume and renal hemodynamics by AVP were markedly accentuated whereas natriuretic effects were attenuated. However, a marked natriuresis caused by AVP in control right kidney still persistently existed. These results suggest that the AVP-induced natriuresis may occur in two-different ways: one is indirect hormonal including prostaglandins and the other is tubular.


Subject(s)
Rabbits , Arginine Vasopressin , Arginine , Blood Pressure , Glomerular Filtration Rate , Hemodynamics , Kidney , Natriuresis , Natriuretic Agents , Pituitary Gland, Posterior , Prostaglandins , Renal Artery , Renal Circulation , Renin , Sodium , Water
13.
Journal of Korean Society of Endocrinology ; : 760-778, 2000.
Article in Korean | WPRIM | ID: wpr-58093

ABSTRACT

No Abstract Available.


Subject(s)
Natriuretic Peptides
14.
Korean Journal of Nephrology ; : 1012-1023, 2000.
Article in Korean | WPRIM | ID: wpr-161189

ABSTRACT

It has long been known that acetylcholine infusion resulted in increases in urine volume, urinary excretion of Na and renal plasma flow. Exact mechanism of renal effects of acetylcholine, however, has not yet been clarified. Since the discovery of endothelium-derived relaxing factor/nitric oxide system, the vascular endothelium has been considered as an endocrine gland. The purpose of the present study was to define the effect of acetylcholine on the renal hemodynamic and tubular function, and the modification of the renal effects of acetylcholine in two- kidney one clip Goldblatt hypertensive rabbits. Intrarenal acetylcholine(0.03-0.3ug/kg/min) increased glomerular filtration rate(GFR, CCr), renal plasma flow (RPF, CPAH), urine volume(UV), free water clearance (CH2O), urinary excretion of electrolytes(UNaV, UKV) and nitrate(UNO3V) and fractional excretion of Na+ (FENa) in unanesthetized rabbits. No change in filtration fraction was observed. Pretreatment with N omega- nitro-L-arginine methyl ester(L-NAME) blocked the acetylcholine-induced renal effects. Acetylcholine infused into the contralateral kidney elicited increases in GFR, RPF, UV, CH2O, UNaV, UKV, UNO3V and FENa in hypertensive rabbits. The hemodynamic effect was not different between normotensive sham-operated and unilateral nephrectomized rabbits. Acetylcholine-induced tubular effect, however, was significantly accentuated in hypertensive rabbits. Neither the renal hemodynamic nor tubular effects of acetylcholine were observed with pretreatment of L-NAME. These results suggest that the renal tubular effect as well as hemodynamic effect of acetylcholine is mediated through the NO system and that the tubular effect of acetylcholine is accentuated in the early phase of renal hypertension.


Subject(s)
Rabbits , Acetylcholine , Endocrine Glands , Endothelium, Vascular , Filtration , Hemodynamics , Hypertension, Renal , Kidney , NG-Nitroarginine Methyl Ester , Nitric Oxide , Renal Plasma Flow , Water
15.
Korean Journal of Urology ; : 387-394, 2000.
Article in Korean | WPRIM | ID: wpr-128544

ABSTRACT

No abstract available.


Subject(s)
Muscle, Smooth , Renin , Renin-Angiotensin System
16.
Korean Journal of Nephrology ; : 837-846, 2000.
Article in Korean | WPRIM | ID: wpr-9262

ABSTRACT

Arginine vasotocin has long been known as an antidiuretic hormone in non-mammalian vertebrates. The peptide has also been found in mammalian tissues. The physiological significance of the peptide, however, has not yet been clarified in mammals. To define the effect of arginine vasotocin on the water and electrolyte balance in mammalian vertebrates, experiments have been done. Intrarenal arterial infusion of arginine vasotocin, 0.01-10ng/kg/min resulted in dose-dependent decreases in urine volume and free water clearance and an increase in urinary osmolarity. Arginine vasotocin, in a dose of 0.03ng/kg/min, induced an increase in water reabsorption without changes in glomerular filtration rate. Intrarenal infusion of arginine vasotocin in doses ranging from 0.1 to 3.0 or 10.0ng/kg/min resulted in decreases in glomerular filtration rate and renal plasma flow. However, no dose dependence were observed. Intrarenal infusion of arginine vasotocin from 0.3 to 10 ng/kg/min induced dose-dependent natriuretic and kaliuretic effects with concomitant suppression of renin secretion. The renal effects of arginine vasotocin were blocked by arginine vasopressin V2-receptor antagonist [d(CH2)5, D-Phe2, Ile4, Ala9-NH2]-vasopressin but were not blocked by[d(CH2)5, D-Ile2, Ile4, Arg8]- vaso pression. These data suggest that the effect of arginine vasotocin on the renal function are similar to that of vasopressin in mammalian vertebrates. The data also suggest that the renal effects of arginine vasotocin may be coupled to the receptor system which is similar, if not identical, to that of arginine vasopressin.


Subject(s)
Arginine Vasopressin , Arginine , Glomerular Filtration Rate , Mammals , Osmolar Concentration , Renal Plasma Flow , Renin , Vasopressins , Vasotocin , Vertebrates , Water , Water-Electrolyte Balance
17.
The Korean Journal of Physiology and Pharmacology ; : 393-401, 2000.
Article in English | WPRIM | ID: wpr-728137

ABSTRACT

To define the postnatal changes in ANP secretion in response to mechanical stretch and atrial compliance, experiments have been done in perfused nonbeating rabbit atria with different ages: 1-day, 1-, 2-, 3-, 4-, and 8-wk-old. In 1-day-old-rabbits, an increase in intraatrial pressure resulted in an increase in atrial volume, which was higher than that in 1-wk-old rabbits. Increases in atrial volume stimulated the secretion of ANP with concomitant translocation of extracellular fluid (ECF) into the atrial lumen. However, mechanically stimulated ECF translocation was lower in 1-day-old rabbits than that in 1-wk-old rabbits. Therefore, positive relationship between mechanically stimulated ECF translocation and ANP secretion was shifted upward in 1-day-old rabbits, as compared to 1-wk-old rabbits. Changes in atrial volume and ECF translocation were gradually increased with aging and reached the peak value at 4 wk. The stretch-induced ANP secretion in terms of ECF translocation (the interstitial ANP concentration) was also increased with aging and reached the peak value at 4 wk. The interstitial ANP concentration was dependent on the atrial content of ANP. These data suggest that the higher level of atrial ANP secretion is related to the postnatal changes in atrial volume and unidentified factor.


Subject(s)
Rabbits , Aging , Atrial Natriuretic Factor , Atrial Pressure , Compliance , Extracellular Fluid
18.
Korean Journal of Urology ; : 1219-1224, 1999.
Article in Korean | WPRIM | ID: wpr-208866

ABSTRACT

PURPOSE: Angiotensin(ANG) II regulates tone of penile smooth muscle for erection. ANG III is a product converted from ANG II by aminopeptidase A. The effects of ANG III have not been clarified in the penile corpus cavernosum. The purpose of the present experiment was to determine whether the ANG III has regulatory function in the control of rabbit corpus cavernosum smooth muscle tone. MATERIALS AND METHODS: A strip of rabbit corpus cavernosum was mounted in an organ chamber to measure the isometric tension. We compared the effects of ANG III(10-7M to 10-5M), ANG II(10-8M to 10-6M) and ANG I(10-7M to 10-5M) on the contractility of the corpus cavernosum smooth muscle. RESULTS: ANG III, ANG II, and ANG I contracted corpus cavernosum smooth muscle strips dose-dependently. The contraction of smooth muscle induced by ANG III was 10 fold less by ANG II. Contractile response to ANG III was not attenuated by captopril(angiotensin converting enzyme inhibitor). Contractile response to ANG III was significantly inhibited by Dup 753 of 10-7M(type 1 specific ANG II receptor inhibitor) but not inhibited by PD 123,319 of 10-6M(type 2 specific ANG II inhibitor). CONCLUSIONS: The present results suggest that ANG III is involved in the regulation of corpus cavernosum smooth muscle tone, and contractile effect to ANG III produced via activation of type 1 ANG II (AT1) receptor. The rank order of potency of contraction was as follows, ANG II>ANG IIIANG I.


Subject(s)
Angiotensin I , Angiotensin II , Angiotensin III , Angiotensins , Glutamyl Aminopeptidase , Losartan , Muscle, Smooth
19.
Journal of the Korean Ophthalmological Society ; : 1184-1194, 1999.
Article in Korean | WPRIM | ID: wpr-89833

ABSTRACT

Atrial natriuretic peptide(ANP), a peptide hormone synthesized mainly in the cardiac atrium, has an important physiological role on the regulation of body fluid and electrolyte balance. Extraatrial ANP system has been reported. The presence of ANP in eye has also been reported. ANP in the eye has claimed to control the intraocular pressure. However, the presence of ANP and its receptors in the intraocular tissues are controversial. Therefore, the purpose of the present study was to determine the characteristics of molecular nature of ANP and its receptors in variable intraocular tissues of cow. Immunoreactive ANP was detected in aqueous humor(10+/-1 pg/ml), cornea (3.6+/-0.5 pg/mg), ciliary body(2.62+/-0.6 pg/mg), choroid(2.1+/-0.5 pg/mg), retina (1.7+/-0.2 pg/mg)and iris(1.4+/-0.5 pg/mg). Chromatographic characterization of molecular profile of ANP showed major peak corresponding to small molecular weight forms of ANP and minor peak corresponding to proANP. ANP mRNA was detected in the cornea, retina and ciliary body using reverse transcriptase-polymerase chain reaction. The production of cGMP by the activation of guanylyl cyclase was stimulated by ANP, BNP and CNP in tissue membranes of cornea, ciliary body and iris. Autoradiographic study showed that the corneal endothelium had A, B, and C subtypes of natriuretic peptide receptor. Longitudinal fibers of ciliary muscle and retina had A subtype of natriuretic receptor. These results suggest that the bovine eye has its own ANP system and ANP may have an important paracrine or autocrine function in the eye.


Subject(s)
Aqueous Humor , Atrial Natriuretic Factor , Autoradiography , Body Fluids , Ciliary Body , Cornea , Endothelium, Corneal , Guanylate Cyclase , Intraocular Pressure , Iris , Membranes , Molecular Weight , Receptors, Peptide , Retina , RNA, Messenger , Water-Electrolyte Balance
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