Effects of Prostaglandin F<SUB>2</SUB><SUB>α</SUB> on Membrane Potentials and K<SUP>&#8290;</SUP> Currents in Rabbit Middle Cerebral Arterial Cells

Effects of Prostaglandin F<SUB>2</SUB><SUB>α</SUB> on Membrane Potentials and K<SUP>&#8290;</SUP> Currents in Rabbit Middle Cerebral Arterial Cells

<P> The purpose of our investigation was to examine the effects of prostaglandin F<SUB>2</SUB><SUB>α</SUB> (PGF<SUB>2</SUB><SUB>α</SUB>) on membrane potentials, Ca<SUP>2&#8290;</SUP>-activated K<SUP>&#8290;</SUP> (K<SUB>Ca</SUB>) channels, and delayed rectifier K<SUP>&#8290;</SUP> (K<SUB>V</SUB>) channels using the patch-clamp technique in single rabbit middle cerebral arterial smooth muscle cells. PGF<SUB>2</SUB><SUB>α</SUB> significantly hyperpolarized membrane potentials and increased outward whole-cell K<SUP>&#8290;</SUP> currents. PGF<SUB>2</SUB><SUB>α</SUB> increased open-state probability of K<SUB>Ca</SUB> channels without the change of the open and closed kinetics. PGF<SUB>2</SUB><SUB>α</SUB> increased the amplitudes of K<SUB>V</SUB> currents with a leftward shift of activation and inactivation curves and a decrease of activation time constant. Our results suggest that the activation of K<SUB>Ca</SUB> and K<SUB>V</SUB> channels, at least in part, may lead to attenuate or counteract vasoconstriction by PGF<SUB>2</SUB><SUB>α</SUB> in middle cerebral artery.