Attenuation of endothelin-1-induced calcium response by tyrosine kinase inhibitors in vascular smooth muscle cells

Cynthia Y. Liu, Michael Sturek

Research output: Contribution to journalArticle

30 Scopus citations

Abstract

Although tyrosine kinases play an important role in cell growth and have been implicated in regulation of smooth muscle contraction, their role in agonist-induced myoplasmic Ca2+ responses is unclear. We examined effects of the tyrosine kinase inhibitors genistein and methyl 2,5-dihydroxycinnamate (MDHC) on the endothelin-1 (ET-1)-induced Ca2+ response and determined underlying mechanisms for the effects. Freshly isolated smooth muscle cells from porcine coronary arteries were loaded with fura 2 ester, and myoplasmic free Ca2+ (Ca(m)/2+) concentration was estimated with fura 2 microfluorometry. Both genistein and MDHC inhibited the initial transient Ca(m)/2+ response to ET by 54 and 81%, respectively (P < 0.05), in the presence of extracellular Ca2+. Genistein also significantly delayed the Ca(m)/2+ response, with the latent period from ET-1 application to the beginning of the Ca(m)/2+ response being increased from 1.08 ± 0.17 to 2.65 ± 0.52 min (P < 0.05). In the absence of extracellular Ca2+, genistein inhibited the ET-1-induced Ca(m)/2+ response by 93% (P < 0.05). The Ca(m)/2+ responses to caffeine (5 mM) or inositol trisphosphate (IP3) applied intracellularly via a patch-clamp pipette were not affected by genistein. Both genistein and MDHC also abolished the sustained Ca(m)/2+ response to ET-1. However, the Ca(m)/2+ response to depolarization by 80 mM K+ was not inhibited by MDHC and only inhibited 22% by genistein (P < 0.05). These results indicate that 1) activation of tyrosine kinases is an important regulatory mechanism for the ET-1-induced Ca(m)/2+ response in vascular smooth muscle and 2) tyrosine kinases mediate ET-1-induced Ca2+ release with no direct effect on IP3-mediated Ca2+ release. Thus ET-1-mediated signaling upstream of IP3 interaction with the Ca2+ stores is regulated by tyrosine kinases.

Original languageEnglish (US)
Pages (from-to)C1825-C1833
JournalAmerican Journal of Physiology - Cell Physiology
Volume270
Issue number6 39-6
DOIs
StatePublished - Jun 1996

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Keywords

  • caffeine
  • fura 2
  • genistein
  • inositol trisphosphate
  • methyl 2,5-dihydroxycinnamate
  • sarcoplasmic reticulum
  • whole cell current

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Cell Biology
  • Physiology
  • Physiology (medical)

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