Mechanisms of endothelin-1-induced contraction in pulmonary arteries from chronically hypoxic rats

• Published in: American journal of physiology. Lung cellular and molecular physiology Vol. 290; no. 2; pp. L284 - L290
• Main Authors: Weigand, Letitia, Sylvester, J. T, Shimoda, Larissa A
• Format: Journal Article
• Language: English
• Published: United States 01.02.2006
• Subjects: 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine - analogs & derivatives; 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine - pharmacology; 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid - pharmacology; Amides - pharmacology; Animals; Azepines - pharmacology; Endothelin-1 - pharmacology; Enzyme Inhibitors - pharmacology; Genistein - pharmacology; Hypoxia - physiopathology; Indoles - pharmacology; Intracellular Signaling Peptides and Proteins; Isometric Contraction - drug effects; Male; Maleimides - pharmacology; Myosin-Light-Chain Kinase - antagonists & inhibitors; Potassium Chloride - pharmacology; Protein Kinase C - antagonists & inhibitors; Protein-Serine-Threonine Kinases - antagonists & inhibitors; Protein-Tyrosine Kinases - antagonists & inhibitors; Pulmonary Artery - drug effects; Pulmonary Artery - physiopathology; Pyridines - pharmacology; Pyrimidines - pharmacology; Rats; Rats, Wistar; rho-Associated Kinases; src-Family Kinases - antagonists & inhibitors; Staurosporine - pharmacology; Vasoconstriction - drug effects
• ISSN: 1040-0605; 1522-1504
• DOI: 10.1152/ajplung.00449.2004

Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland Submitted 1 December 2004 ; accepted in final form 6 September 2005 Endothelin-1 (ET-1), a potent vasoconstrictor, is believed to contribute to the pathogenesis of hypoxic pulmonary hypertension. Previously we demonstrated that contraction induced by ET-1 in intrapulmonary arteries (IPA) from chronically hypoxic (CH) rats occurred independently of changes in intracellular Ca 2+ concentration ([Ca 2+ ] i ), suggesting that ET-1 increased Ca 2+ sensitivity. The mechanisms underlying this effect are unclear but could involve the activation of myosin light chain kinase, Rho kinase, PKC, or tyrosine kinases (TKs), including those from the Src family. In this study, we examined the effect of pharmacological inhibitors of these kinases on maximum tension generated by IPA from CH rats (10% O 2 for 21 days) in response to ET-1. Experiments were conducted in the presence of nifedipine, an L-type Ca 2+ channel blocker, to isolate the component of contraction that occurred without a change in [Ca 2+ ] i . The mean change in tension caused by ET-1 (10 –8 M) expressed as a percent of the maximum response to KCl was 184.0 ± 39.0%. This response was markedly inhibited by the Rho kinase inhibitors Y-27632 and HA-1077 and the TK inhibitors genistein, tyrphostin A23, and PP2. In contrast, staurosporine and GF-109203X, inhibitors of PKC, had no significant inhibitory effect on the tension generated in response to ET-1. We conclude that the component of ET-1-induced contraction that occurs without a change in [Ca 2+ ] i in IPA from CH rats requires activation of Rho kinase and TKs, but not PKC. Y-27632; HA-1077 Address for reprint requests and other correspondence: L. A. Shimoda, Division of Pulmonary and Critical Care Medicine, Johns Hopkins Univ., 5501 Hopkins Bayview Circle, JHAAC 4B.82B, Baltimore, MD 21224 (e-mail: shimodal{at}welch.jhu.edu )