Phorbol Esters Stimulate Calcium Influx via Voltage-Dependent Channels in A7r5 Vascular Smooth-Muscle Cells
Phorbol esters have been shown to cause a slowly developing and sustained contraction of vascular smooth muscle from a variety of species (Rasmussenet al., 1984; Danthuluri and Deth, 1984; Forderet al., 1985; Gleason and Flaim, 1986; Sybertzet al., 1986; Chatterjee and Tejada, 1986). This action of phorbol esters is presumed to be due to stimulation of protein kinase C., a Ca2+ -phospholipid-dependent protein kinase (Nishizuka, 1984; Castagnaet al., 1982). Phorbol ester-stimulated vascular smooth muscle contraction in many systems is dependent on extracellular Ca2+ (Rasmussenet al., 1984; Danthuluri and Deth, 1984; Forderet al., 1985; Gleason and Flaim, 1986). In rabbit aorta, phorbol-stimulated contraction is inhibited by organic Ca2+ channel antagonists, and is facilitated by the Ca2+ channel agonist BAY K 8644 or by an increase in extracellular Ca2+ concentration (Forderet al., 1985).
KeywordsVascular Smooth Muscle Phorbol Ester Influx Rate Rabbit Aorta A7r5 Cell
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