Effects of Pinacidil, Cromakalim, and Nicorandil on Potassium Currents of Rat Basilar Artery Smooth Muscle
Pinacidil, nicorandil, and cromakalim are antihypertensive agents, which relax peripheral vascular smooth muscle by hyperpolarizing smooth muscle cells towards the potassium equilibrium potential (Weir and Weston, 1986; Southerton et al., 1988). These drugs increase 86Rb+ or 42K+ efflux and reverse or attenuate the effects of a wide variety of vasoconstrictors (Hamilton et al., 1989). Patch-clamping studies show that these drugs act on several types of potassium channels. In cardiac myocytes, nicorandil (Hiraoka and Fan, 1989), pinacidil (Escande et al., 1989), and cromakalim (Sanguinetti et al., 1988) usually activate a background, time- and voltage-independent potassium current which is blocked by physiological levels of ATP. In arterial and venous smooth muscles, these agents activate either large-conductance calcium-dependent potassium channels (Gelband et al., 1989) or ATP-dependent potassium channels (Standen et al., 1989). Nicorandil has a dual action, a stimulation of guanylate cyclase and an increase in potassium conductance (Newgreen et al., 1988).
KeywordsPotassium Channel Basilar Artery Potassium Current Cerebral Vasospasm Single Channel Recording
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