Abstract
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 storngly 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.