Two Ca-dependent K-channels classified by the application of tetraethylammonium distribute to smooth muscle membranes of the rabbit portal vein.

摘要: Dispersed single smooth muscle cells of rabbit portal vein were prepared by treatment with collagenase and trypsin. The 100–300 μm in length, 5–10 maximum width cylindrical shape. In insideout membrane patches, two different amplitudes ionic currents recorded, these channel conductances 273 pS (Kl-channel) 92 (Ks-channel), when both sides the exposed to 142 mM K+ solution. depended on concentrations membrane. When replaced Na+ or Tris+, single-channel abolished. concentration Ca2+ inside was greater than 10−7 M, activity enhanced but there enhancement applied extracellular surface, ranging between 10−9 10−3 M. During application tetraethylammonium (TEA+; 1–10 mM) intracellular current types K-channel not modified. By contrast TEA+ (0.1–1 reduced increased noise levels during open-state Kl-channels, did have such an effect Ks-channel. We conclude that are at least Ca-dependent K-channels distributed vein. surface blocks activation Kl-channel, These do seem be important for maintenance resting potential, play role repolarizing stage Ca spikes,