Metabotropic Ca2+ channel-induced calcium release in vascular smooth muscle.
Contraction of vascular smooth muscle cells (VSMCs) depends on the rise of cytosolic [Ca(2+)] owing to either Ca(2+) influx through voltage-gated Ca(2+) channels of the plasmalemma or to receptor-mediated Ca(2+) release from the sarcoplasmic reticulum (SR). Although the ionotropic role of L-type Ca(2+) channels is well known, we review here data suggesting a new role of these channels in arterial myocytes. After sensing membrane depolarization Ca(2+) channels activate G proteins and the phospholipase C/inositol 1,4,5-trisphosphate (InsP(3)) pathway. Ca(2+) released through InsP(3)-dependent channels of the SR activates ryanodine receptors to amplify the cytosolic Ca(2+) signal, thus triggering arterial cerebral vasoconstriction in the absence of extracellular calcium influx. This metabotropic action of L-type Ca(2+) channels, denoted as calcium channel-induced Ca(2+) release, could have implications in cerebral vascular pharmacology and pathophysiology, because it can be suppressed by Ca(2+) channel antagonists and potentiated with small concentrations of extracellular vasoactive agents as ATP.
Ureña
Juan
J
Laboratorio de Investigaciones Biomédicas, Departamento de Fisiología and Hospital Universitario Virgen del Rocío, Universidad de Sevilla, E-41013 Seville, Spain.
del Valle-Rodríguez
Alberto
A
López-Barneo
José
J
D000818:Animals; D001158:Arteries / Q000378:metabolism / Q000502:physiology; D002118:Calcium / Q000378:metabolism*; D020746:Calcium Channels, L-Type / Q000502:physiology*; D020013:Calcium Signaling; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D008954:Models, Biological; D009119:Muscle Contraction; D009131:Muscle, Smooth, Vascular / Q000378:metabolism* / Q000502:physiology; D051381:Rats; D010738:Type C Phospholipases / Q000378:metabolism
D020746:Calcium Channels, L-Type; D015544:Inositol 1,4,5-Trisphosphate; D010738:Type C Phospholipases; D002118:Calcium