endothelin-1 and zaprinast

The effects of 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB), anthracene-9-carboxylate (9-AC) (chloride channel blockers) and zaprinast (an inhibitor of phosphodiesterase-5) on endothelin-1 (ET-1) induced contractions of pregnant rat myometrium were investigated in vitro.. Isolated myometrial strips were obtained from pregnant rats, and the strips were mounted in organ baths for recording of isometric tension (n=8). The effects of 10(-7) to 10(-4)M NPPB, 10(-7) to 10(-4)M 9-AC, and 10(-7) to 10(-4)M zaprinast on 10(-8)M ET-1-induced contractions of pregnant rat myometrial smooth muscle were recorded.. NPPB and 9-AC increased the amplitude of ET-1-induced myometrial contractions, while decreasing the frequency, in a concentration-dependent manner. The amplitude of myometrial contractions were significantly increased by NPPB and 9-AC beginning from the concentration of 10(-6)M. The frequency of myometrial contractions were significantly decreased by NPPB and 9-AC beginning from the concentration of 10(-6)M. Zaprinast inhibited the amplitude and frequency of ET-1-induced myometrial contractions in a concentration-dependent manner. Zaprinast-induced decreases in amplitude and frequency of myometrial contractions reached statistical significance beginning from the concentrations of 10(-7)M and 10(-5)M, respectively.. These data provide evidence that the ET-1-induced contractions of pregnant rat myometrial strips may be modulated by chloride channels. In addition, zaprinast effectively inhibited ET-1-induced contractions in pregnant rat myometrium.

Topics: 3',5'-Cyclic-GMP Phosphodiesterases; Animals; Anthracenes; Calcium; Chloride Channels; Cyclic Nucleotide Phosphodiesterases, Type 5; Endothelin-1; Female; Myometrium; Nitrobenzoates; Phosphodiesterase Inhibitors; Phosphoric Diester Hydrolases; Pregnancy; Purinones; Rats; Rats, Wistar; Uterine Contraction

Calcitonin gene-related peptide (CGRP) is believed to play an important role in maintaining low pulmonary vascular resistance (PVR) and in modulating pulmonary vascular responses to chronic hypoxia; however, the effects of adenovirally mediated gene transfer of CGRP on the response to hypoxia are unknown.. In the present study, an adenoviral vector encoding prepro-CGRP (AdRSVCGRP) was used to examine the effects of in vivo gene transfer of CGRP on increases in PVR, right ventricular mass (RVM), and pulmonary vascular remodeling that occur in chronic hypoxia in the mouse. Intratracheal administration of AdRSVCGRP, followed by 16 days of chronic hypoxia (FIO(2) 0.10), increased lung CGRP and cAMP levels. The increase in pulmonary arterial pressure (PAP), PVR, RVM, and pulmonary vascular remodeling in response to chronic hypoxia was attenuated in animals overexpressing prepro-CGRP, whereas systemic pressure was not altered while in chronically hypoxic mice, angiotensin II and endothelin-1-induced increases in PAP were reduced, whereas decreases in PAP in response to CGRP and adrenomedullin were not changed and decreases in PAP in response to a cAMP phosphodiesterase inhibitor were enhanced by AdRSVCGRP.. In vivo CGRP lung gene transfer attenuates the increase in PVR and RVM, pulmonary vascular remodeling, and pressor responses in chronically hypoxic mice, suggesting that CGRP gene transfer alone and with a cAMP phosphodiesterase inhibitor may be useful for the treatment of pulmonary hypertensive disorders.

Topics: Adenoviridae; Adrenomedullin; Animals; beta-Galactosidase; Calcitonin Gene-Related Peptide; Cyclic AMP; Cyclic GMP; Endothelin-1; Genes, Reporter; Genetic Therapy; Genetic Vectors; Hemodynamics; Humans; Hypertension, Pulmonary; Hypoxia; Lung; Mice; NG-Nitroarginine Methyl Ester; Peptides; Phosphodiesterase Inhibitors; Potassium Channels; Protein Precursors; Purinones; Recombinant Fusion Proteins; Rolipram; Second Messenger Systems; Transfection; Vasoconstriction; Vasoconstrictor Agents; Vasodilator Agents

The aim of this study was to assess the role of nitric oxide (NO) and endothelin (ET)-1 in the pathophysiology of persistent pulmonary hypertension of the newborn in fetal lambs with a surgically created congenital diaphragmatic hernia (CDH). The pulmonary vascular response to various agonists and antagonists was assessed in vivo between 128 and 132 days gestation. Age-matched fetal lambs served as control animals. Control and CDH lambs had similar pulmonary vasodilator responses to acetylcholine, sodium nitroprusside, zaprinast, and dipyridamole. The ET(A)-receptor antagonist BQ-123 caused a significantly greater pulmonary vasodilatation in CDH than in control animals. The ET(B)-receptor agonist sarafotoxin 6c induced a biphasic response, with a sustained pulmonary vasoconstriction after a transient pulmonary vasodilatation that was not seen in CDH animals. We conclude that the NO signaling pathway in vivo is intact in experimental CDH. In contrast, ET(A)-receptor blockade and ET(B)-receptor stimulation significantly differed in CDH animals compared with control animals. Imbalance of ET-1-receptor activation favoring pulmonary vasoconstriction rather than altered NO-mediated pulmonary vasodilatation is likely to account for persistent pulmonary hypertension of the newborn in fetal lambs with a surgically created CDH.

Topics: Acetylcholine; Animals; Antihypertensive Agents; Cyclic GMP; Dipyridamole; Disease Models, Animal; Endothelin Receptor Antagonists; Endothelin-1; Endothelium, Vascular; Female; Hernia, Diaphragmatic; Hernias, Diaphragmatic, Congenital; Hypertension, Pulmonary; Nitric Oxide; Nitroprusside; Peptides, Cyclic; Phosphodiesterase Inhibitors; Pregnancy; Pulmonary Circulation; Purinones; Receptor, Endothelin A; Receptor, Endothelin B; Receptors, Endothelin; Sheep; Vasoconstrictor Agents; Vasodilator Agents; Viper Venoms

The effects of transfer of the endothelial nitric oxide synthase (eNOS) gene to the lung were studied in mice. After intratracheal administration of AdCMVbetagal, expression of the beta-galactosidase reporter gene was detected in pulmonary airway cells, in alveolar cells, and in small pulmonary arteries. Gene expression with AdCMVbetagal peaked 1 day after administration and decayed over a 7- to 14-day period, whereas gene expression after AdRSVbetagal transfection peaked on day 5 and was sustained over a 21- to 28-day period. One day after administration of AdCMVeNOS, eNOS protein levels were increased, and there was a small reduction in mean pulmonary arterial pressure and pulmonary vascular resistance. The pressure-flow relationship in the pulmonary vascular bed was shifted to the right in animals transfected with eNOS, and pulmonary vasodepressor responses to bradykinin and the type V cGMP-selective phosphodiesterase inhibitor zaprinast were enhanced, whereas systemic responses were not altered. Pulmonary vasopressor responses to endothelin-1 (ET-1), angiotensin II, and ventilatory hypoxia were reduced significantly in animals transfected with the eNOS gene, whereas pressor responses to norepinephrine and U46619 were not changed. Systemic pressor responses to ET-1 and angiotensin II were similar in eNOS-transfected mice and in control mice. Intratracheal administration of AdRSVeNOS attenuated the increase in pulmonary arterial pressure in mice exposed to the fibrogenic anticancer agent bleomycin. These data suggest that transfer of the eNOS gene in vivo can selectively reduce pulmonary vascular resistance and pulmonary pressor responses to ET-1, angiotensin II, and hypoxia; enhance pulmonary depressor responses; and attenuate pulmonary hypertension induced by bleomycin. Moreover, these data suggest that in vivo gene transfer may be a useful therapeutic intervention for the treatment of pulmonary hypertensive disorders.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Adenoviridae; Angiotensin II; Animals; Antimetabolites, Antineoplastic; beta-Galactosidase; Bleomycin; Blood Flow Velocity; Blood Pressure; Bradykinin; Cyclic GMP; Endothelin-1; Gene Transfer Techniques; Genes, Reporter; Hypertension, Pulmonary; Hypoxia; Mice; Mice, Inbred Strains; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Norepinephrine; Phosphodiesterase Inhibitors; Pulmonary Alveoli; Pulmonary Artery; Pulmonary Circulation; Pulmonary Wedge Pressure; Purinones; Sympathomimetics; Vasoconstrictor Agents

In the coronary circulation, endothelin-1 (ET-1) evokes spasms which are difficult to treat when the endothelial integrity is compromised. This study compares several classes of relaxing agents on already established contractions to ET-1 in an in vitro model using ring segments of the porcine left descending coronary artery (pLAD). All segments were precontracted with 10 nmol/L ET-1. The calcium channel blocker isradipine was 300 times more potent than verapamil, but was only a partial relaxant; the maximal relaxation obtained was 52 +/- 2% (n = 6). Atrial natriuretic peptide (ANP) was an equally potent relaxant of the ET-1 contraction; however, it too was an incomplete relaxant, maximal relaxation being < 60%. A 50% relaxation of the ET-1 contraction was obtained with 0.28 +/- 0.24 mumol/L ANP, n = 4 (IC50). Comparison of cyclic nucleotide analogues revealed a 30 times higher potency for 8-bromo-cyclic guanosine monophosphate (8-Br-cGMP)(IC50 44 +/- 11 mumol/L, n = 6) than for 8-bromo-cyclic adenosine monophosphate (8-Bi-cAMP) (IC50 1600 mumol/L, n = 6). The cyclic nucleotide phosphodiesterase (PDE) inhibitor milrinone, a PDE 3-inhibitor with an IC50 2.4 +/- 1.8 mumol/L, (n = 6) was 10 times more potent than rolipram (PDE 4-inhibitor), zaprinast (PDE 5-inhibitor) and vinpocentine (PDE 1-inhibitor). Withdrawal of these analogues and inhibitors from segments continuously exposed to 10 nmol/l ET-1 revealed that vinpocentine and 8-Br-cGMP were irreversible relaxants, in contrast to milrinone and 8-Br-cAMP. In conclusion, this study has demonstrated that cGMP-enhancing agents, such as the naturally occurring ANP, the calcium channel blocker isradipine, and the synthetic inhibitor of PDE 3, were the most effective relaxants of ET-1 evoked contractions in pLAD in vitro.

Topics: 8-Bromo Cyclic Adenosine Monophosphate; Animals; Atrial Natriuretic Factor; Caffeine; Calcium Channel Blockers; Calcium Channels; Calcium Channels, L-Type; Colforsin; Coronary Vessels; Cyclic AMP; Cyclic GMP; Dose-Response Relationship, Drug; Endothelin-1; In Vitro Techniques; Isradipine; Milrinone; Muscle, Smooth, Vascular; Papaverine; Phosphodiesterase Inhibitors; Phosphoric Diester Hydrolases; Purinones; Pyrrolidinones; Rolipram; Swine; Vasoactive Intestinal Peptide; Vasoconstriction; Vasodilation; Verapamil; Vinca Alkaloids