Ca2+ homeostasis in vascular smooth muscle.

The free intracellular calcium concentration is an important link in the excitation-contraction coupling mechanism of vascular smooth muscle. In this review, some current topics about vascular smooth muscle as regards Ca2+ storage, Ca2+ release, Ca2+ extrusion and Ca2+ regulation are discussed. Particular attention is paid to Ca2+ mobilized from the sarcoplasmic reticulum, the physiologically important Ca2+ reservoir in vascular smooth muscle. This occurs through two Ca2+ release channels: the inositol 1,4,5-trisphosphate receptor and the ryanodine receptor; the characteristics, function and control of these two receptors are summarized. Emphasis is also placed on a role of the nucleus as a potential Ca2+ storage site.