Vasa recta pericytes express a strong inward rectifier K+ conductance

Chunhua Cao, Jae Hwan Goo, Whaseon Lee-Kwon, Thomas L. Pallone
2006 American Journal of Physiology. Regulatory Integrative and Comparative Physiology  
Strong inward rectifier potassium channels are expressed by some vascular smooth muscle cells and facilitate K ϩ -induced hyperpolarization. Using whole cell patch clamp of isolated descending vasa recta (DVR), we tested whether strong inward rectifier K ϩ currents are present in smooth muscle and pericytes. Increasing extracellular K ϩ from 5 to 50 and 140 mmol/l induced inward rectifying currents. Those currents were Ba 2ϩ sensitive and reversed at the K ϩ equilibrium potential imposed by the
more » ... electrode and extracellular buffers. Ba 2ϩ binding constants in symmetrical K ϩ varied between 0.24 and 24 mol/l at Ϫ150 and Ϫ20 mV, respectively. Ba 2ϩ blockade was time and voltage dependent. Extracellular Cs ϩ also blocked the inward currents with binding constants between 268 and 4,938 mol/l at Ϫ150 and Ϫ50 mV, respectively. Ba 2ϩ (30 mol/l) and ouabain (1 mmol/l) depolarized pericytes by an average of 11 and 24 mV, respectively. Elevation of extracellular K ϩ from 5 to 10 mmol/l hyperpolarized pericytes by 6 mV. That hyperpolarization was reversed by Ba 2ϩ (30 mol/l). We conclude that strong inward rectifier K ϩ channels and Na ϩ -K ϩ -ATPase contribute to resting potential and that K IR channels can mediate K ϩ -induced hyperpolarization of DVR pericytes.
doi:10.1152/ajpregu.00877.2005 pmid:16439665 fatcat:mbellakcnvekxmc3nqwepbyvyu