Effects of prostaglandin F2 on membrane currents in rabbit middle cerebral arterial smooth muscle cells

Kim, Nari, Jin Han, and Euiyong Kim. Effects of prostaglandin F2 on membrane currents in rabbit middle cerebral arterial smooth muscle cells. Am J Physiol Heart Circ Physiol 284: H1018–H1027, 2003; 10.1152/ajpheart. 01022.2001.—Although PGF2 affects contractility of vascular smooth muscles, no studies to date have addressed the electrophysiological mechanism of this effect. The purpose of our investigation was to examine the direct effects of PGF2 on membrane potentials, Ca2 -activated K (KCa) channels, delayed rectifier K (KV) channels, and L-type Ca2 channels with the patch-clamp technique in single rabbit middle cerebral arterial smooth muscle cells (SMCs). PGF2 significantly hyperpolarized membrane potentials and increased the amplitudes of total K currents. PGF2 increased open-state probability but had little effect on the open and closed kinetics of KCa channels. PGF2 increased the amplitudes of KV currents with a leftward shift of the activation and inactivation curves and a decrease in the activation time constant. PGF2 decreased the amplitudes of L-type Ca2 currents without any significant change in threshold or apparent reversal potentials. This study provides the first finding that the direct effects of PGF2 on middle cerebral arterial SMCs, at least in part, could attenuate vasoconstriction.