Vasa recta pericytes express a strong inward rectifier K+ conductance
- PMID: 16439665
- DOI: 10.1152/ajpregu.00877.2005
Vasa recta pericytes express a strong inward rectifier K+ conductance
Abstract
Strong inward rectifier potassium channels are expressed by some vascular smooth muscle cells and facilitate K+-induced hyperpolarization. Using whole cell patch clamp of isolated descending vasa recta (DVR), we tested whether strong inward rectifier K+ currents are present in smooth muscle and pericytes. Increasing extracellular K+ from 5 to 50 and 140 mmol/l induced inward rectifying currents. Those currents were Ba2+ sensitive and reversed at the K+ equilibrium potential imposed by the electrode and extracellular buffers. Ba2+ binding constants in symmetrical K+ varied between 0.24 and 24 micromol/l at -150 and -20 mV, respectively. Ba2+ blockade was time and voltage dependent. Extracellular Cs+ also blocked the inward currents with binding constants between 268 and 4,938 micromol/l at -150 and -50 mV, respectively. Ba2+ (30 micromol/l) and ouabain (1 mmol/l) depolarized pericytes by an average of 11 and 24 mV, respectively. Elevation of extracellular K+ from 5 to 10 mmol/l hyperpolarized pericytes by 6 mV. That hyperpolarization was reversed by Ba2+ (30 micromol/l). We conclude that strong inward rectifier K+ channels and Na+-K+-ATPase contribute to resting potential and that KIR channels can mediate K+-induced hyperpolarization of DVR pericytes.
Comment in
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Inward rectifier currents in pericytes.Am J Physiol Regul Integr Comp Physiol. 2006 Jun;290(6):R1598-600. doi: 10.1152/ajpregu.00127.2006. Am J Physiol Regul Integr Comp Physiol. 2006. PMID: 16682469 No abstract available.
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