Low-conductance K channels in apical membrane of rat cortical collecting tubule

摘要: Low-conductance, K-selective channels were identified in the apical membrane of rat cortical collecting tubule (CCT) by use patch-clamp technique. Isolated, split tubules bathed K gluconate medium to depolarize cell while keeping intracellular concentration high. With pipette containing predominantly either Na+ or Li+ but no K, outward currents observed through that had a single-channel conductance (g) 9 pS and probability being open (Po) greater than 0.9, independent voltage (+/- 40 mV) applied (Vp). Similarly, only when patch was excised into high-K solution, implying high selectivity channel for K+. When 1 mM BaCl2 added pipette, Po decreased 0.36 at Vp = 0; however, g not changed flickered rapidly between blocked states; as made positive, increased negative. filled with...