Control of descending vasa recta pericyte membrane potential by angiotensin II.
Using nystatin perforated-patch whole cell recording, we investigated the role of Cl(-) conductance in the modulation of outer medullary descending vasa recta (OMDVR) pericyte membrane potential (Psi m) by ANG II. ANG II (10(-11) to 10(-7) M) consistently depolarized OMDVR and induced Psi m oscillations at lower concentrations. The Cl(-) channel blockers anthracene-9-decarboxylate (1 mM) and niflumic acid (10 microM) hyperpolarized resting pericytes and repolarized ANG II-treated pericytes. In voltage-clamp experiments, ANG II-treated pericytes exhibited slowly activating currents that were nearly eliminated by treatment with niflumic acid (10 microM) or removal of extracellular Ca(2+). Those currents reversed at -31 and -10 mV when extracellular Cl(-) concentration was 152 and 34 mM, respectively. In pericytes held at -70 mV, oscillating inward currents were sometimes observed; the reversal potential also shifted with extracellular Cl(-) concentration. We conclude that ANG II activates a Ca(2+)-dependent Cl(-) conductance in OMDVR pericytes to induce membrane depolarization and Psi m oscillations.
Pallone
Thomas L
TL
Division of Nephrology, School of Medicine, University of Maryland, Baltimore, Maryland 21201-1595, USA. tpallone@medicine.umaryland.edu
Huang
James M-C
JM
D000804:Angiotensin II / Q000494:pharmacology / Q000502:physiology*; D000818:Animals; D001683:Biological Clocks / Q000502:physiology; D018118:Chloride Channels / Q000037:antagonists & inhibitors; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D007679:Kidney Medulla / Q000098:blood supply* / Q000187:drug effects / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008833:Microcirculation / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D009544:Niflumic Acid / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D020286:Pericytes / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D018118:Chloride Channels; D000804:Angiotensin II; D009544:Niflumic Acid