This study was designed to observe the differences between main pulmonary arteries and the third-order branches of pulmonary arteries in the contractile response to phenylephrine (Phen), endothelin-1 (ET-1) and potassium chloride (KCl). The vascular tension changes of main and the third-order branches of pulmonary arteries induced by KCl, ET-1 and Phen were recorded by traditional vascular tone detection methods and microvascular ring technique, respectively. The results showed that Phen could cause a significant contraction in main pulmonary arteries, but did not induce apparent contraction in the third-order branches of pulmonary arteries. Compared with main pulmonary arteries, ET-1 contracted the third-order branches of pulmonary arteries with reduced maximal response value and PDvalue. In comparison with the main pulmonary arteries, contraction caused by KCl was enhanced in the third-order branches of pulmonary arteries. The results suggest that the vascular reactivity of main and the third-order branches of pulmonary arteries is different and it is important to study the vascular function of small branches of pulmonary arteries. This study could provide an important experimental basis for the further study on vascular function of small branches of pulmonary arteries and the functional changes in pulmonary hypertension.
Animals ; Endothelin-1 ; pharmacology ; Male ; Phenylephrine ; pharmacology ; Potassium Chloride ; pharmacology ; Pulmonary Artery ; drug effects ; Rats ; Vasoconstriction

OBJECTIVETo study the selective dilatation effects of iptakalim (Ipt) on basilar and pulmonary arterioles, and endothelial cell function of these arterioles in hypoxic rats.

METHODSSD male rats were divided into 2 groups:control and hypoxic group fed in normobaric hypoxic environment (O2 7.8%, 8 h). Arteriole rings about (204 + 5) pm were isolated and the tension of hypoxic arterioles pre-contracted by 6 nmol/L endothelin-1 (ET-1) was observed with wire myograph system model (DMT 610 m). The relaxing response of hypoxic arterioles induced by different concentration of Ipt were detected and endothelial activity was also tested by acetylcholine.

RESULTS10(5) mol/L acetylcholine (ACh)-mediated vasodilatation of basilar and pulmonary arterioles was greatly reduced in the hypoxic group than those in control group (P < 0.05). Compared with normal group, a novel ATP-sensitive potassium channel opener Ipt at the concentration ranging from 10(-11) mol/L to 10(3) mol/L, caused stronger dose dependent vasodilatation on hypoxic pulmonary arterioles, and there was no significant difference between control and hypoxic basilar arterioles.

CONCLUSIONThe endothelial function of basilar and pulmonary arterioles was damaged under hypoxic state, and Ipt selectively increased dilatation effects on hypoxic pulmonary arterioles, but not on hypoxic basilar arterioles which could improve high altitude pulmonary edema pathological state and be the novel drug in the treatment of pulmonary hypertension.

Acetylcholine ; pharmacology ; Altitude ; Altitude Sickness ; physiopathology ; Animals ; Arterioles ; drug effects ; Dilatation ; Endothelin-1 ; pharmacology ; Hypoxia ; KATP Channels ; drug effects ; Male ; Propylamines ; pharmacology ; Rats ; Vasodilation ; Vasodilator Agents ; pharmacology

OBJECTIVETo observe the contraction effect of endothelin-1 (ET-1) on human hepatic stellate cells (HSCs) and the inhibition of salianic-acid B (SA-B) on ET-1, to explore the acting link and the possible mechanism.

METHODSHSC were isolated from human normal liver tissue by enzyme digestion and Nycondenz density gradient centrifugation. The contraction of ET-1 on passage HSCs and the intervention of SA-B with three doses (low-, middle-, and high-) on the contraction were observed by collagen gel contraction. ET-1 and SA-B were directly added to the serum-free medium of HSCs, then calcium ion concentration was detected by laser scanning confocal microscope.

RESULTSCollagen gel contraction experiments showed that ET-1 could induce the contraction of HSC directly (P < 0.01). Three doses of SA-B significantly inhibited the contraction effects of ET-1 on HSCs (all P < 0.01). After adding the ET-1, HSCs morphology changed obviously with the number of cells decreased. However, SA-B inhibited the changes. Laser scanning confocal microscope experiments revealed that ET-1 stimulated the transiently rapid increase of intracellular calcium ion concentration, and the effects was obviously inhibited when SA-B was added.

CONCLUSIONSSA-B could inhibit the contraction of HSCs induced by ET-1, and its mechanism might be related to the lowing of free calcium ion concentration in HSCs. This anti-contraction effect of SA-B is perhaps one of the mechanisms of its anti-fibrosis and anti-portal hypertension effects.

Benzofurans ; pharmacology ; Cells, Cultured ; Endothelin-1 ; antagonists & inhibitors ; Hepatic Stellate Cells ; cytology ; Humans ; Isometric Contraction ; drug effects

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

The aim of the present study was to investigate the role of caveolin-1 in the inhibition of endothelin-1 induced proliferation of vascular smooth muscle cells (VSMCs) by 17beta-estradiol. In the cultured rat thoracic aortic VSMCs, proliferation of VSMCs was determined by using [(3)H]-thymidine incorporation and the expression of caveolin-1 protein was measured by immunofluorescence assays and Western blotting. The measurement demonstate VSMCs exposed to various concentrations of endothelin-1 (1-100 nmol/L) for 24 h induced an increase in [(3)H]-thymidine incorporation. Pretreament with various concentrations of 17beta-estradiol (0.1-10 nmol/L) for 24 h inhibited the proliferation effect of endothelin-1. Immunofluorescence assays showed that after 24 h treatment of VSMCs with endothelin-1 (100 nmol/L), the expression of caveolin-1 in VSMCs was significantly increased, whereas pretreament with 17beta-estradiol (10 nmol/L) for 24 h inhibited the effect. Western blotting results further proved that endothelin-1 inhibited and 17beta-estradiol increased the expression of caveolin-1 in VSMCs. These results demonstrate that 17beta-estradiol inhibits the VSMCs proliferation induced by endothelin-1, and that the effect of estradiol is probably mediated by caveolin-1.
Animals ; Aorta, Thoracic ; cytology ; Caveolin 1 ; physiology ; Cell Division ; Cells, Cultured ; Endothelin-1 ; antagonists & inhibitors ; physiology ; Estradiol ; pharmacology ; Muscle, Smooth, Vascular ; cytology ; Rats ; Rats, Sprague-Dawley

Animals ; Arrhythmias, Cardiac ; chemically induced ; prevention & control ; Cats ; Endothelin-1 ; adverse effects ; Medulla Oblongata ; drug effects ; Metoprolol ; pharmacology ; gamma-Aminobutyric Acid ; pharmacology

OBJECTIVETo study the effects of iptakalim (Ipt), an ATP-sensitive potassium channel opener, on cardiac remodeling induced by isoproterenol (ISO) in Wistar rats.

METHODSISO was given subcutaneously (85 mg/(kg x d), sc, 7 days) to induce cardiac remodeling in rats. The rats in Ipt treated group were administrated with Ipt 3 mg/kg (po) after ISO injection. After treated with Ipt for 6 weeks, the hemodynamic parameters were tested by an eight channel physiological recorder (RM-6000). Then the heart weight was weighed and the cardiac remodeling index was calculated. HE stain and Masson's stain were employed to perform histological analysis, the hydroxyproline(Hyp) content in cardiac tissue was detected by colorimetric method, radioimmunoassay was used to measure the plasma levels of endothelin-1 (ET-1) and prostacyclin (PGI2).

RESULTSSix weeks after ISO injection, the cardiac functions of model group were damaged markedly compared with those of normal group. The characteristics of ventricular remodeling in model group included that the heart weight index, myocyte cross-sectional area, myocardial fibrosis, and the hydroxyproline content in cardiac tissue were all increased significantly. The plasma level of ET-1 was increased, while the plasma level of PGI2 was decreased significantly. These changes could be reversed by Ipt treatment (3 mg/(kg x d) for 6 weeks).

CONCLUSIONIpt can reverse cardiac remodeling induced by isoproterenol in rats. The endothelial protective effect regulating effects of Ipt on the balance between the ET-1 and PGI2 system may be involved in its mechanisms.

Animals ; Endothelin-1 ; blood ; Hemodynamics ; Hydroxyproline ; metabolism ; Isoproterenol ; pharmacology ; KATP Channels ; drug effects ; Male ; Myocardium ; metabolism ; Propylamines ; pharmacology ; Prostaglandins I ; blood ; Rats ; Rats, Wistar ; Ventricular Remodeling ; drug effects

AIMTo elucidate the independent or combined effects of endothelin-1 (ET-1) and prostaglandin F2alpha (PGF2alpha) on cardiomyocytes and investigate the relationship between hypertrophy and apoptosis of cardiomyocytes.

METHODSCultured neonatal rat cardiomyocytes were stained with FITC-conjugated phalloidin and eosin to detect the cardiomyocyte hypertrophy evidenced by increased sarcomeric structure and cell size. Cardiomyocytes were stained with Hoechst 33258 to detect apoptotic nuclei showing features of condensation and fragmentation.

RESULTSCardiomyocyte hypertrophy induced by ET-1 or PGF2, shown a dose dependent effect. The area of cardiomyocytes treated by 10 nmol/L or 100 nmol/L of ET-1 for 24 h increased 68% or 84% as compared with control, respectively. The area of cardiomyocytes exposed to 10 nmol/L or 100 nmol/L of PGF2alpha for 24 h increased 28% or 106% as compared with control, respectively. The ET-1 and PGF2alpha had a synergic effect on cardiomyocyte hypertrophy, but not superimposed effect. The area of cardiomyocytes increased 80%, 122%, 96%, and 199% in 10 nmol/L ET-1 plus 10 nmol/L PGF2, 10 nmol/L ET-1 plus 100 nmol/L PGF2alpha, 100 nmol/L ET-1 plus 10 nmol/L PGF2alpha, and 100 nmol/L ET-1 plus 100 nmol/L PGF2alpha group, respectively. There were no changes in apoptotic rate of cardiomyocytes treated by ET-1 or PGF2alpha alone for 48 h. The apoptotic rate of cardiomyocytes also didn't increase in ET-1 plus PGF2alpha treatment for 24 h groups, but significantly increased in ET-1 plus PGF2alpha treatment for 48 h groups. ET-1 or PGF2alpha could induce an increase in apoptotic rate of hypertrophic cardiomyocytes. There was a positive relationship between hypertrophic extent and apoptotic rate in cardiomyocytes.

CONCLUSIONThe cardiomyocytes treated by ET-1 or PGF2alpha alone only show hypertrophy, but treatment of ET-1 plus PGF2alpha for 48 h induces apoptosis of cardiomyocytes.

Animals ; Apoptosis ; drug effects ; Cells, Cultured ; Dinoprost ; administration & dosage ; pharmacology ; Dose-Response Relationship, Drug ; Endothelin-1 ; administration & dosage ; pharmacology ; Myocytes, Cardiac ; cytology ; drug effects ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo study the effect of endothelin-1 (ET-1) and its antagonists on the expression of endothelin and its receptors mRNA in HSC-T6 cells.

METHODSCultured HSC-T6 cells were randomly divided into 7 groups: Sham control group, ET-1 group (10 nmol/L ET-1), BQ-123 group [1 micromol/L BQ-123, a selective endothelin receptor A (ETRA) antagonist], BQ-788 group [1 micromol/L BQ-788, a selective endothelin receptor B (ETRB) antagonist], ET-1 + BQ123 group (10 nmol/L ET-1 + 1 micromol/L BQ-123), ET-1 + BQ-788 group (10 nmol/L ET-1 + 1 micromol/L BQ-788) and ET-1 + BQ-788 group (10 nmol/L ET-1 + 1 micromol/L BQ-123 + 1 micromol/L BQ-788). The expression of endothelin receptor mRNA of HSC-T6 cells was determined by reverse-transcription polymerase chain reaction (RT-PCR).

RESULTSThe expression of ETRA mRNA in ET-1 + BQ123 + BQ788 and ET-1 + BQ788 group was significantly lower than ET-1 group (0.329 +/- 0.044 and 0.292 +/- 0.023 vs. 0.440 +/- 0.030 P < 0.05). Compared with ET-1 group, the expression of ETRB mRNA in ET-1 + BQ788 group was down regulated obviously (0.499 +/- 0.136 vs. 0.153 +/- 0.071, P < 0.05). There was no significant difference in ET-1 + BQ123 group and ET-1 + BQ123 + BQ788 group when compared with ET-1 group (0.499 +/- 0.136 vs. 0.496 +/- 0.103 and 0.299 +/- 0.129, P > 0.05).

CONCLUSIONSET-1 has no obvious effect on the expression of ETRA mRNA in HSC-T6. ET-1 may up-regulate the expression of ETRB mRNA. Act on ETRA receptor, ET-1 can inhibit the expression of ETRB mRNA.

Animals ; Cells, Cultured ; Endothelin-1 ; pharmacology ; Gene Expression Regulation ; drug effects ; Hepatocytes ; drug effects ; metabolism ; Oligopeptides ; pharmacology ; Peptides, Cyclic ; pharmacology ; Piperidines ; pharmacology ; RNA, Messenger ; genetics ; Rats ; Rats, Sprague-Dawley ; Receptor, Endothelin A ; biosynthesis ; drug effects ; genetics ; Receptor, Endothelin B ; biosynthesis ; drug effects ; genetics

To explore the roles of regulatory peptides in the process of various anaphylactic inflammation of the airway, we observed the influence of four peptides, i.e., vasoactive intestinal peptide (VIP), epidermal growth factor (EGF), endothelin-1 (ET-1), and calcitonin gene-related peptide (CGRP), on the adhesion of eosinophil (EOS) to unstimulated and O(3)-stressed bronchial epithelial cells (BEC). From the experiments we observed that VIP and EGF decreased EOS adherence to O(3)-stressed BEC and downregulated airway inflammation; ET-1 and CGRP increased the adhesion of EOS to BEC in the inflammatory process; and CGRP aggravated O(3)-stressed reactions. The effects of ET-1 and CGRP were inhibited by W(7)and H(7). Anti-ICAM-1 antibody inhibited the adhesion of EOS to BEC, which brings to light that EOS adherence to BEC may be related to the expression of ICAM-1 of BEC.
Animals ; Antibodies ; pharmacology ; Bronchi ; cytology ; Cell Adhesion ; drug effects ; physiology ; Cells, Cultured ; Endothelin-1 ; pharmacology ; Eosinophils ; physiology ; Epidermal Growth Factor ; pharmacology ; Epithelial Cells ; physiology ; Female ; Intercellular Adhesion Molecule-1 ; immunology ; physiology ; Male ; Rabbits ; Vasoactive Intestinal Peptide ; pharmacology