Membrane mechanisms of regulating Ca ion concentration in smooth muscle cells. II. System of passive Ca2+ transport in smooth muscles

The aim of this review is to summarize some current aspects on the membrane mechanisms of energy-independent Ca2+ transport in the smooth muscles. The emphasis is placed on the characteristics of voltage-gated and receptor-operated calcium channels of plasma membrane and two major Ca2+ release channels of sarco(endo)plasmic reticulum: one is activated by IP3 and sensitive to heparin and the other by Ca2+ and sensitive to ryanodine. A brief discussion of the electro- and pharmacomechanical coupling mechanisms in the smooth muscle is given.