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This Article Full Text Full Text (PDF) All Versions of this Article: 290/2/L284    most recent 00449.2004v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (18) Citing Articles via Google Scholar Google Scholar Articles by Weigand, L. Articles by Shimoda, L. A. Search for Related Content PubMed PubMed Citation Articles by Weigand, L. Articles by Shimoda, L. A.

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

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 Ca²⁺ concentration ([Ca²⁺]_i), suggesting that ET-1 increased Ca²⁺ 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% O₂ for 21 days) in response to ET-1. Experiments were conducted in the presence of nifedipine, an L-type Ca²⁺ channel blocker, to isolate the component of contraction that occurred without a change in [Ca²⁺]_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 [Ca²⁺]_i in IPA from CH rats requires activation of Rho kinase and TKs, but not PKC.

Y-27632; HA-1077

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