Pinacidil actions on ion channels in vascular muscle.

Electrophysiological and mechanical recordings from isolated single vascular muscle cells and isolated segments of caudal artery showed that pinacidil caused vascular muscle relaxation and hyperpolarization which originates from increased K+ conductance. Voltage-clamp recordings of current flow through single K+ channels strongly suggest that pinacidil increases the specific type of K+ conductance associated with the Ca2+-dependent "big" K+ channel (unit conductance of 200 pS in symmetrical K+ solutions). The increased opening of K+ channels appears certain to be an important cellular mechanism to vasodilation by pinacidil.