Alkaline pH shifts Ca2+ sparks to Ca2+ waves in smooth muscle cells of pressurized cerebral arteries

Thomas J. Heppner, Adrian D. Bonev, Luis Fernando Santana, Mark T. Nelson

Research output: Contribution to journalArticle

36 Scopus citations

Abstract

The effects of external pH (7.0-8.0) on intracellular Ca2+ signals (Ca2+ sparks and Ca2+ waves) were examined in smooth muscle cells from intact pressurized arteries from rats. Elevating the external pH from 7.4 to 7.5 increased the frequency of local, Ca2+ transients, or "Ca2+ sparks," and, at pH 7.6, significantly increased the frequency of Ca2+ waves. Alkaline pH-induced Ca2+ waves were inhibited by blocking Ca2+ release from ryanodine receptors but were not prevented by inhibitors of voltage-dependent Ca2+ channels, phospholipase C, or inositol 1,4,5-trisphosphate receptors. Activating ryanodine receptors with caffeine (5 mM) at pH 7.4 also induced repetitive Ca2+ waves. Alkalization from pH 7.4 to pH 7.8-8.0 induced a rapid and large vasoconstriction. Approximately 82% of the alkaline pH-induced vasoconstriction was reversed by inhibitors of voltage-dependent Ca2+ channels. The remaining constriction was reversed by inhibition of ryanodine receptors. These findings indicate that alkaline pH-induced Ca2+ waves originate from ryanodine receptors and make a minor, direct contribution to alkaline pH-induced vasoconstriction.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume283
Issue number6 52-6
StatePublished - Dec 1 2002
Externally publishedYes

Keywords

  • Arterial diameter
  • Ryanodine receptors
  • Voltage-dependent calcium channels

ASJC Scopus subject areas

  • Physiology

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