Stimulation of Ca2+ influx by endothelin-1 is subject to negative feedback by elevated intracellular Ca2+

L. L. Muldoon, H. Enslen, K. D. Rodland, B. E. Magun

Research output: Contribution to journalArticle

30 Scopus citations

Abstract

Endothelin-1 (ET-1) has been shown to require Ca2+ influx for activation of vascular smooth muscle in vivo, but in vitro models show that ET-1 mobilizes intracellular Ca2+ and is independent of extracellular Ca2+. We present data that suggest ET-1 modulates cellular responses through a dual mechanism involving both phosphatidylinositol turnover and Ca2+ channel activation. Addition of low concentrations of ET-1 (<10-9 M) to serum-deprived quiescent Rat-1 cells stimulated Ca2+ influx while having little effect on diacylglycerol (DG) release or intracellular Ca2+ levels. In contrast, higher concentrations of ET-1 (>10-9 M) stimulated intracellular Ca2+ transients and release of inositol trisphosphate (IP3) and DG but did not activate Ca2+ uptake. Stimulation of Ca2+ influx at low [ET-1] could not be accounted for by depletion of intracellular IP3-sensitive pools. Neither the stimulation of Ca2+ influx at low [ET-1] nor the inhibitory actions of high [ET-1] could be mimicked by the activation of protein kinase C. We tested the hypothesis that elevated intracellular Ca2+ was inhibitory for Ca2+ influx. When intracellular Ca2+ transients were maintained below ~165 nM by chelation with BAPTA or BAPTA derivatives with altered affinity for Ca2+, Ca2+ influx was stimulated over the entire range of ET-1 concentrations. In addition, experimentally elevating intracellular Ca2+ levels with the tumor promoter thapsigargin abolished ET-1-stimulated Ca2+ influx. These data suggest that the biological consequences of ET-1 release may be determined by local concentration differences. Thus in vascular smooth muscle cells ET-1 may act either to mobilize intracellular Ca2+ or to promote Ca2+ influx, depending on the distance from the endothelial cell source in the vascular wall. The activation of different processes by low and high ET-1 concentrations may determine the physiological response to ET-1 stimulation in vivo.

Original languageEnglish (US)
Pages (from-to)C1273-C1281
JournalAmerican Journal of Physiology - Cell Physiology
Volume260
Issue number6 29/6
DOIs
StatePublished - 1991

Keywords

  • 1,2-bis(2-aminophenoxy) ethane-N,N,N',N'-tetraacetic acid
  • Protein kinase C
  • Thapsigargin

ASJC Scopus subject areas

  • Physiology
  • Cell Biology

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