Ca2+ channel-sarcoplasmic reticulum coupling: a mechanism of arterial myocyte contraction without Ca2+ influx

EMBO J. 2003 Sep 1;22(17):4337-45. doi: 10.1093/emboj/cdg432.

Abstract

Contraction of vascular smooth muscle cells (VSMCs) depends on the rise of cytosolic [Ca2+] owing to either Ca2+ influx through voltage-gated Ca2+ channels of the plasmalemma or receptor-mediated Ca2+ release from the sarcoplasmic reticulum (SR). We show that voltage-gated Ca2+ channels in arterial myocytes mediate fast Ca2+ release from the SR and contraction without the need of Ca2+ influx. After sensing membrane depolarization, Ca2+ channels activate G proteins and the phospholipase C-inositol 1,4,5-trisphosphate (InsP3) pathway. Ca2+ released through InsP3-dependent channels of the SR activates ryanodine receptors to amplify the cytosolic Ca2+ signal. These observations demonstrate a new mechanism of signaling SR Ca(2+)-release channels and reveal an unexpected function of voltage-gated Ca2+ channels in arterial myocytes. Our findings may have therapeutic implications as the calcium-channel-induced Ca2+ release from the SR can be suppressed by Ca(2+)-channel antagonists.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium Channels / metabolism*
  • Calcium Signaling
  • GTP-Binding Proteins / metabolism
  • In Vitro Techniques
  • Inositol 1,4,5-Trisphosphate / metabolism
  • Membrane Potentials
  • Muscle Contraction / physiology
  • Muscle, Smooth, Vascular / cytology
  • Muscle, Smooth, Vascular / physiology
  • Myocytes, Smooth Muscle / physiology*
  • Rats
  • Rats, Wistar
  • Ryanodine Receptor Calcium Release Channel / metabolism
  • Sarcoplasmic Reticulum / metabolism*
  • Type C Phospholipases / metabolism

Substances

  • Calcium Channels
  • Ryanodine Receptor Calcium Release Channel
  • Inositol 1,4,5-Trisphosphate
  • Type C Phospholipases
  • GTP-Binding Proteins