Primary action of endothelin on Ca release in bovine coronary artery smooth muscle cells

C. Wagner-Mann, L. Bowman, M. Sturek

Research output: Contribution to journalArticle

29 Scopus citations

Abstract

Intracellular free Ca concentrations (Ca(i)) were determined by fura-2 microfluorometry in single freshly dispersed cells to differentiate endothelin (ET)-induced Ca release from Ca influx through voltage-gated Ca channels (VGCC). In physiological solution ET (10-8 M) significantly (P < 0.05) increased Ca(i) 23 ± 3% (±SE) above baseline; this increase was not significantly attenuated by 2 x 10-4 M lanthanum, a blocker of VGCC, or Ca-free solution. When the sarcoplasmic reticulum was depleted of Ca by prolonged treatment with 5 x 10-3 M caffeine, depolarization with 80 mM K (80K; or 30K) plus ET did not increase Ca(i) above that induced by 80K (or 30K) in caffeine alone. In contrast, 10-6 M BAY K 8644, instead of ET in the protocol, significantly (P < 0.05) increased Ca(i) above that induced by 80K (or 30K). ET released Ca from the caffeine-sensitive internal store but was not rapid and transient like caffeine-induced release, which elicited a peak Ca(i) increase in <1 min; instead, release was more gradual and prolonged with Ca(i) peaking in >2 min, thus resembling the response to 10-5 M ryanodine. With two ET exposures, either a transient nonrepeatable increase in Ca(i) or a delayed, but sustained, increase in Ca(i) resulted, similar to the response to ryanodine. These data indicate that in freshly dispersed bovine cells the predominant mechanism by which ET increases Ca(i) is release of Ca from the sarcoplasmic reticulum; if any increase in L-type voltage-gated Ca influx occurred, it was minimal and matched by efflux.

Original languageEnglish (US)
Pages (from-to)C763-C770
JournalAmerican Journal of Physiology - Cell Physiology
Volume260
Issue number4 29-4
DOIs
StatePublished - Jan 1 1991

Keywords

  • BAY K 8644
  • Caffeine
  • Fura-2 microfluorometry
  • Ryanodine
  • Sarcoplasmic reticulum
  • Voltage-gated calcium channels

ASJC Scopus subject areas

  • Physiology
  • Cell Biology

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