The favorable effects of estrogen on cardiovascular diseases can be explained by several mechanisms such as changes in serum lipid profiles and thrombogenecity. Estrogen also affects the vascular tone, but there has been no report in which the effect of estrogen was tested comprehensively for several vasoactive substances, especially after long-term administration. Two weeks after bilateral ovariectomy in 8-week old female Sprague-Dawley rats, placebo or 17 beta-estradiol (E2) pellets (0.5 mg; released over 3 weeks) were implanted subcutaneously. Two weeks after pellet implantation, organ chamber experiments were performed using aortae. Compared with control, E2-treated vessels showed impaired endothelium-dependent relaxation to acetylcholine. E2 enhanced the contraction to norepinephrine and U46619 and had no effect on endothelin-1-induced contraction. In contrast, the contraction to angiotensin (AT)-II was inhibited by E2. Northern blot analysis for AT1 receptor expression using cultured aortic smooth muscle cells showed no difference between control and E2-treated cells, suggesting that AT1 receptor downregulation is not the likely mechanism. These results suggest that E2 affects the vascular tone variably according to vasoactive substances.
Animal ; Estradiol/pharmacology* ; Female ; In Vitro ; Ovariectomy* ; Rats ; Rats, Sprague-Dawley ; Vasoconstrictor Agents/pharmacology* ; Vasodilator Agents/pharmacology* ; Vasomotor System/drug effects*

OBJECTIVEIn our study, the function of the third-order branches of the mesentenc artery was measured by microvascular ring technique, which can be used to detect microvascular function in some disease related to microvascular dysfunction.

METHODSIsolated, fixed, standardized and then activated the third-order branches of rat mesenteric artery. Microvascular tone was measured by systolic and diastolic drags respectively, with the help of DMT tension apparatus and PowerLab data acquisition system.

RESULTSThe third-order branches of rat mesenteric artery showed excellent response to vasoactive drugs. The contraction effect of norepinephrine (NE) reached 19 in mN. When acetylcholine (Ach) or sodium nitroprusside (SNP) of 10(9)-10(5)mol/L was added, vascular tones showed gradient drop: 80% of maximal relaxation when adding ACh, while 95% of maximal relaxation when adding SNP.

CONCLUSIONThe third-order branches of the mesenteric artery function was successfully detected by using microvascular ring technique.

Acetylcholine ; pharmacology ; Animals ; In Vitro Techniques ; Male ; Mesenteric Arteries ; drug effects ; physiology ; Nitroprusside ; pharmacology ; Norepinephrine ; pharmacology ; Rats ; Vasoconstrictor Agents ; pharmacology ; Vasodilation ; physiology ; Vasodilator Agents ; pharmacology

OBJECTIVETo examine the effect of cinobufacini on rat thoracic aorta and its mechanism.

METHODSIsolated rat thoracic aorta was perfused and isometric tension was recorded by organ bath technique before and after cinobufacini treatment.

RESULTCinobufacini induced contraction of isolated thoracic aorta with or without endothelium in a concentration-dependent manner (at concentration of 2.5,5.0,7.5,10.0 g/L). The vasoconstriction effect of cinobufacini was more potent in endothelium-denuded aorta ring [(16.3+/-3.39)%, (52.5+/-7.70)%, (60.9+/-8.84)%, (69.2+/-11.34)%] than in endothelium-intact aorta ring [(6.2+/-2.07)%, (14.7+/-4.91), (17.6+/-5.86)%, (20.3+/-6.78)% (P<0.01)]. Its contractile effect was attenuated in Ca(2+)-free solution (about 1/10 of that in buffer with 1.25 mmol/L CaCl(2)) or by the treatment with verapamil (10(-7)mol/L), an L-type calcium channel antagonist. Cinobufacini induced contraction on the endothelium-intact rat aorta was augmented by pretreatment with L-NAME (10(-4)mol/L), a nitric oxide synthase inhibitor.

CONCLUSIONCinobufacini contracts rat thoracic aorta by opening the voltage-dependent Ca(2+) channel and increasing Ca(2+) influx into vascular smooth muscle. Cinobufacini can also stimulate the release of vascular relaxant factor, nitric oxide, from the endothelium and thus antagonize cinobufacini-induced contraction.

Animals ; Aorta, Thoracic ; drug effects ; Bufanolides ; pharmacology ; Endothelium, Vascular ; drug effects ; metabolism ; In Vitro Techniques ; Male ; Nitric Oxide ; biosynthesis ; Rats ; Rats, Sprague-Dawley ; Vasoconstriction ; drug effects ; Vasoconstrictor Agents ; pharmacology

In patients with variant angina, previous data have been inconclusive as to whether basal coronary artery tone is elevated at the spastic and non-spastic sites. Thus, the purpose of this study was to assess the basa coronary artery tone and the responsiveness to acetylcholine (Ach) and ergonovine (Erg) in patients with variant angina. We compared the basal coronary artery tone and the constrictive responses to Ach and Erg between 31 patients (Group 1) with variant angina in whom spasm was provoked by the low doses of Ach (intracoronary 20 micrograms) or Erg(intravenous 50 micrograms) and 35 patients (Group 2) provoked by higher doses of Ach (intracoronary 100 micrograms) or Erg (intravenous cumulative dose of 350 micrograms), and 26 control subjects. Patients with variant angina in whom spasm was provoked by low doses of Ach or Erg, had a higher incidence of mixed disease, multi-vessel spasm and higher disease activity. The basal coronary artery tone at the spastic and nonspastic sites of spasm related artery was significantly more elevated in Group 1 than that in Group 2 (44+/- 17 vs 14 +/- 11% and 26 +/- 14 vs 16 +/- 10% respectively, P< 0.05), but not in the nonspasm related artery, The magnitudes of vasoconstrictive responses to Ach and Erg at the nonspastic sites were also greater in Group 1 than those in Group 2 and the control groups (Ach; 40 +/- 20 vs 26+/- 11, 27 +/- 12%: Erg; 37 +/- 18 vs 12 +/- 8, 13 +/- 10% respectively, P< 0.05). However, the basal coronary artery tone was not elevated at the spastic and nonspastic sites in Group 2 compared to the in control subjects. These findings suggest that the basal coronary artery tone is increased in patients with variant angina with higher disease activity at the spastic sites and nonspastic sites of the spasm-related artery, and this may be related to the occurrence of coronary artery spasm.
Acetylcholine/pharmacology ; Angina Pectoris, Variant/physiopathology ; Coronary Vessels/*drug effects/physiopathology ; Dose-Response Relationship, Drug ; Ergonovine/*pharmacology ; Female ; Human ; Male ; Middle Age ; Nitroglycerin/pharmacology ; Spasm/chemically induced/physiopathology ; Vasoconstriction/drug effects/physiology ; Vasoconstrictor Agents/*pharmacology ; Vasodilator Agents/pharmacology

OBJECTIVETo study the relaxant effects of glycyrrhizinate and salvianolic acid B on rat portal vein in vitro.

METHODSHealthy female Wistar rats were canalized from hepatic artery, portal vein and hepatic vein in vitro. Remained blood in liver was eliminated with heparinized Krebs-Henseleit solution through hepatic artery, then the liver was isolated under infusing manner. Being constricted with phenylephrine and relaxed with acetylcholine, and infused with glycyrrhizinate or salvianolic acid B, the portal pressures of infused rat livers were consistently monitored by BL-420S physiological experiment system. The median effective concentration (EC50) of the two agents were analyzed with non-linear various slope regression using Prism-4 software.

RESULTSEC50 of glycyrrhizinate in relaxing the phenylephrine-contracted portal was 1.5556 x 10(-9) mol/L, suggesting one of the mechanism of action of diammonium glycyrhizinate for the treatment of portal hypertension was direct relaxation. Salvianolic acid B showed constrictive action on the phenylephrine-retracted portal vein, the EC50 was 1.4639 x 10(-9) mol/L, indicating that its indirect control action was took part in the portal hypertension therapy synergistically.

CONCLUSIONUnder the mode with both controlled-velocity and monitored pressure, glycyrrhizinate showed relaxation and salvianolic acid B showed constriction on portal pressure in vitro.

Animals ; Benzofurans ; pharmacology ; Blood Pressure ; drug effects ; Female ; Glycyrrhizic Acid ; pharmacology ; Hypertension, Portal ; physiopathology ; Phenylephrine ; pharmacology ; Portal Vein ; physiology ; Rats ; Rats, Wistar ; Vasoconstrictor Agents ; pharmacology ; Vasodilator Agents ; pharmacology ; Vasomotor System ; drug effects

AIMTo investigate the relaxation mechanisms of neferine (Nef) on the rabbit corpus cavernosum tissue in vitro.

METHODSStrips of rabbit corpus cavernosum were mounted in organ chambers. The effects of Nef were examined on isolated muscle strips precontracted with phenylephrine (PE) alone, in the presence of N(W)-nitro-L-arginine (LNNA, a nitric oxide synthase inhibitor), 1-H-[1,2,4]oxadiazolo[4,3-alpha]quinoxalin-1-one (ODQ, a guanylyl cyclase inhibitor), indomethacin (cyclooxygenase inhibitor), tetraethylammonium (Ca(2+)-activated K(+) channel blocker), 4-aminopiridine (4-AP, voltage dependent K(+) channel blocker) and glibenclamide (ATP sensitive K(+) channel blocker). The effects of Nef on KCl-induced contraction of isolated muscle strips were also investigated. The procedure of calcium absence-calcium addition was designed to observe the effect of Nef on two components of the contractile responses to PE based on the source of Ca(2+) (extracellular vs. intracellular).

RESULTSCorpus cavernosum strips relaxed in response to Nef (10(-9)-10(-4) mol/L) in a concentration-dependent manner with an IC(50) of 4.60 X 10(-6) mol/L. However, they were not affected by LNNA, ODQ, indomethacin or K(+)-channel blockers. Nef (10(-6) mol/L, 10(-5) mol/L) concentration dependently reduced the maximal contraction response of isolated strips induced by KCl to 79.3%+/-5.5% and 61.5%+/-3.2%, respectively (P < 0.01). In the calcium absence-calcium addition procedure, Nef 10(-5) mol/L inhibited both intracellular calcium-dependent and extracellular calcium-dependent contraction induced by PE (2 X 10(-5) mol/L) (P < 0.05). The inhibition ratios were 26.2%+/-5.4% and 48.3%+/-7.6%, respectively.

CONCLUSIONThe results of the present study suggest that Nef possesses a relaxant effect on rabbit corpus cavernosum tissues, which is attributable to the inhibition of extracellular Ca2+ influx and the inhibition of release of intracellular stored Ca(2+), but not mediated by the release of nitric oxide, prostaglandins or by the activation of potassium channels.

Animals ; Benzylisoquinolines ; pharmacology ; Calcium ; pharmacology ; Dose-Response Relationship, Drug ; Drugs, Chinese Herbal ; pharmacology ; Male ; Muscle Contraction ; drug effects ; Muscle Relaxation ; drug effects ; Penis ; drug effects ; physiology ; Phenylephrine ; pharmacology ; Potassium Chloride ; pharmacology ; Rabbits ; Vasoconstrictor Agents ; pharmacology

The study is to investigate the effect of angiotensin II (Ang II) and its receptor blockers on migration and endothelin-1 (ET-1) expression of rat vascular adventitial fibroblast subpopulations. Vascular adventitial fibroblasts were individually expanded by using cloning rings, and the effects of Ang II on the migration of adventitial fibroblast subpopulations were evaluated by Transwell. Fluorescence quantitative-PCR detected the expression of preproET-1 mRNA induced by Ang II, and its receptor antagonists losartan and PD-123319. The concentration of ET-1 was determined by ELISA. It showed that spindle shaped and epithelioid shaped cells were isolated by using cloning rings, named as spindle cells and round cells. RT-PCR showed that fibroblast subpopulations did not have leukocytes, endothelial cells and smooth muscle cells, namely pure cell lines. Compared with respective control cells, two subpopulations had transferring ability. Ang II significantly improved round cells migration in a concentration-dependent manner, and had no obvious influence on spindle cells migration. Ang II (1 x 10(-8) - 1 x 10(-6) mol x L(-1)) significantly increased the expression of preproET-1 mRNA in round cells (P < 0.01), and had no significant effect on the expression of preproET-1 mRNA in spindle cells. Losartan blocked the expression of preproET-1 mRNA induced by Ang II in round cells, and had no significant effect on the expression of preproET-1 mRNA in spindle cells. The effects of Ang II and ET-1 receptor inhibitors on the release of ET-1 were similar to the expression of preproET-1 mRNA. The results indicate that there are two cell subpopulations: round cells and spindle cells in rat vascular adventitial fibroblasts. Ang II significantly improved cells migration, and increased the expression of ET-1 in round cell subpopulation. It suggested that there may be different migratory mechanisms in two cell subpopulations, and the two subpopulations may play a different role in vascular remodeling and reparative process.
Angiotensin II ; pharmacology ; Angiotensin Receptor Antagonists ; pharmacology ; Animals ; Cell Movement ; drug effects ; Cells, Cultured ; Endothelin-1 ; genetics ; metabolism ; Fibroblasts ; cytology ; metabolism ; Imidazoles ; pharmacology ; Losartan ; pharmacology ; Male ; Pyridines ; pharmacology ; RNA, Messenger ; metabolism ; Rats ; Rats, Sprague-Dawley ; Vasoconstrictor Agents ; pharmacology

Urotensin II (U II ) is currently the most potent vasoconstrictor. G-protein coupled receptor 14 ( GPR-14) is its specific receptor. This review mainly discribes the structure and distribution of U II and GPR14, the activities that U II and GPR14 stimulates proliferation of vascular smooth muscle cells and vasoconstriction, as well as its mechanism.
Animals ; Arteriosclerosis ; etiology ; Humans ; Hypertension ; etiology ; Receptors, G-Protein-Coupled ; chemistry ; metabolism ; physiology ; Urotensins ; chemistry ; metabolism ; physiology ; Vasoconstrictor Agents ; chemistry ; metabolism ; pharmacology

Isolated rat thoracic aorta which is pharmacologically precontracted by phenylephrine induces photorelaxation when exposed to long wave length UV-light. The aim of the present study was to characterize the mechanism of UV-light induced by photorelaxation in the rat aorta. 1. UV light relaxed both endothelium-intact and -denuded rat aortic rings contracted by phenylephrine. The magnitude of relaxation on UV light was dependent on the exposure time and slightly greatly in endothelium-denuded rings than in endothelium-intact preparations. 2. L-NAME (10 nM-100 uM) but not D-NAME completely inhibited the photorelaxation in a concentration dependent manner. 3. The UV-induced relaxation was inhibited by methylene blue (1 -100 uM), and verapamil (100 nM), and removal of extracellular Ca2+. In contrast, UV-light induced photorelaxation was potentiated by N(w)-nitro-Larginine (L-NOARG) treatment. 4. In immunocytochemical analysis of UV-light induced iNOS and eNOS expression in rat aortas, at which expression levels were increased in a time-dependent manner on UV-irradiation in aortic endothelium and smooth muscle, respectively. These results suggest that UV light-induced photorelaxation may be due to nitric oxide from exogenously administered L-arginine as well as endogenous nitric oxide donors such as amino acid and arginine derivatives. Additional suggestion is that UV light stimulates the expression of nitric oxide synthases, and its activity for nitric oxide generation is dependent on cytosolic Ca2+ originated from extracellular space.
Acetylcholine/pharmacology ; Animals ; Aorta, Thoracic/drug effects/*physiology/radiation effects ; Calcium Channel Blockers/pharmacology ; Cholinergic Agents/pharmacology ; Endothelium, Vascular/drug effects/physiology/radiation effects ; Enzyme Inhibitors/pharmacology ; Female ; Male ; Methylene Blue/pharmacology ; NG-Nitroarginine Methyl Ester/pharmacology ; Nitric Oxide Synthase/antagonists & inhibitors/metabolism ; Phenylephrine/pharmacology ; Rats ; Rats, Sprague-Dawley ; *Ultraviolet Rays ; Vasoconstrictor Agents/pharmacology ; Vasodilation/drug effects/*radiation effects ; Vasodilator Agents/pharmacology ; Verapamil/pharmacology

OBJECTIVETo investigate the effect of endothelin receptors in chronic venous insufficiency (CVI) in lower extremities.

METHODSTen cases of varicose veins from CVI patients (as case group) and ten cases of non-varicose veins (as control group) were investigated in this study. The two groups were divided into two groups respectively: endothelium-intact group and de-endothelium groups. The vasoconstriction mediated by endothelin A (ETA) and endothelin B (ETB) receptors was recorded with myography. The distribution of ETA and ETB receptors was detected by immunohistochemistry method.

RESULTSEndothelin-1 (ET-1) and sarafotoxin 6c (S6c) induced concentration-dependent contraction in the veins. In endothelium-intact veins, the E(max) and pD(2) of contraction curve induced by ET-1 were 132.30% +/- 43.42% and 6.03 +/- 0.35, respectively in control group;and were 19.24% +/- 12.94% and 6.78 +/- 0.46, respectively in case group. The E(max) and pD(2) in case group were much lower than in control group (P < 0.05). The E(max) and pD(2) induced by S6c were 30.10% +/- 12.90% and 6.54 +/- 0.36, respectively in control group, and were 9.61% +/- 1.32% and 6.75 +/- 0.29, respectively in case group; The E(max) in case group was lower than in control group (P < 0.05). In de-endothelium veins, E(max) and pD(2) of S6c were 146.18% +/- 32.33% and 6.50 +/- 0.17 in control group, and 32.93% +/- 3.00% and 6.69 +/- 0.39 in case group; The E(max) in case group was significantly lower than in control group (P < 0.05). ETA receptors was located in endothelium mainly, and ETB receptors in smooth muscle cells mainly. The sites of both ETA and ETB receptors were decreased in case group obviously.

CONCLUSIONSThe contraction mediated by ETA receptor and ETB receptor was decreased with a decrease of ETA receptor and ETB receptor sites in varicose veins of CVI. The contraction insufficiency and down-expression of ETA receptor and ETB receptor are correlated with CVI.

Adult ; Endothelin-1 ; pharmacology ; Humans ; In Vitro Techniques ; Lower Extremity ; blood supply ; Male ; Middle Aged ; Receptors, Endothelin ; drug effects ; physiology ; Vasoconstriction ; drug effects ; physiology ; Vasoconstrictor Agents ; pharmacology ; Venous Insufficiency ; physiopathology ; Viper Venoms ; pharmacology