Thrombin-mediated increases in cytosolic [Ca2+] involve different mechanisms in human pulmonary artery smooth muscle and endothelial cells

Richard S. Sacks, Amy L. Firth, Carmelle V. Remillard, Negin Agange, Jocelyn Yau, Eun A. Ko, Jason X.J. Yuan

Research output: Contribution to journalArticle

11 Scopus citations

Abstract

Thrombin is a procoagulant inflammatory agonist that can disrupt the endothelium-lumen barrier in the lung by causing contraction of endothelial cells and promote pulmonary cell proliferation. Both contraction and proliferation require increases in cytosolic Ca2+ concentration ([Ca2+]cyt). In this study, we compared the effect of thrombin on Ca2+ signaling in human pulmonary artery smooth muscle (PASMC) and endothelial (PAEC) cells. Thrombin increased the [Ca2+]cyt in both cell types; however, the transient response was significantly higher and recovered quicker in the PASMC, suggesting different mechanisms may contribute to thrombin-mediated increases in [Ca2+]cyt in these cell types. Depletion of intracellular stores with cyclopiazonic acid (CPA) in the absence of extracellular Ca2+ induced calcium transients representative of those observed in response to thrombin in both cell types. Interestingly, CPA pretreatment significantly attenuated thrombin-induced Ca2+ release in PASMC; this attenuation was not apparent in PAEC, indicating that a PAEC-specific mechanism was targeted by thrombin. Treatment with a combination of CPA, caffeine, and ryanodine also failed to abolish the thrombin-induced Ca2+ transient in PAEC. Notably, thrombin-induced receptor-mediated calcium influx was still observed in PASMC after CPA pretreatment in the presence of extracellular Ca2+. Ca2+ oscillations were triggered by thrombin in PASMC resulting from a balance of extracellular Ca2+ influx and Ca2+ reuptake by the sarcoplasmic reticulum. The data show that thrombin induces increases in intracellular calcium in PASMC and PAEC with a distinct CPA-, caffeine-, and ryanodineinsensitive release existing only in PAEC. Furthermore, a dynamic balance between Ca2+ influx, intracellular Ca2+ release, and reuptake underlie the Ca2+ transients evoked by thrombin in some PASMC. Understanding of such mechanisms will provide an important insight into thrombin-mediated vascular injury during hypertension.

Original languageEnglish (US)
Pages (from-to)L1048-L1055
JournalAmerican Journal of Physiology - Lung Cellular and Molecular Physiology
Volume295
Issue number6
DOIs
StatePublished - Dec 2008

Keywords

  • Ca store
  • Sarcoplasmic and endoplasmic reticulum

ASJC Scopus subject areas

  • Physiology
  • Pulmonary and Respiratory Medicine
  • Physiology (medical)
  • Cell Biology

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