title: KATP channel conductance of descending vasa recta pericytes.
abstract: Using nystatin-perforated patch-clamp and whole cell recording, we tested the hypothesis that K(ATP) channels contribute to resting conductance of rat descending vasa recta (DVR) pericytes and are modulated by vasoconstrictors. The K(ATP) blocker glybenclamide (Glb; 10 microM) depolarized pericytes and inhibited outward currents of cells held at -40 mV. K(ATP) openers pinacidil (Pnc; 10 microM) and P-1075 (1 microM) hyperpolarized pericytes and transiently augmented outward currents. All effects of Pnc and P-1075 were fully reversed by Glb. Inward currents of pericytes held at -60 mV in symmetrical 140 mM K(+) were markedly augmented by Pnc and fully reversed by Glb. Ramp depolarizations in symmetrical K(+), performed in Pnc and Pnc + Glb, yielded a Pnc-induced, Glb-sensitive K(ATP) difference current that lacked rectification and reversed at 0 mV. Immunostaining identified both K(IR)6.1, K(IR)6.2 inward rectifier subunits and sulfonurea receptor subtype 2B. ANG II (1 and 10 nM) and endothelin-1 (10 nM) but not vasopressin (100 nM) significantly lowered holding current at -40 mV and abolished Pnc-stimulated outward currents. We conclude that DVR pericytes express K(ATP) channels that make a significant contribution to basal K(+) conductance and are inhibited by ANG II and endothelin-1.
authors.affiliation: Division of Nephrology, Department of Medicine, University of Maryland, Baltimore, 21201, USA.
authors.forename: Chunhua
authors.initials: C
authors.lastname: Cao
authors.forename: Whaseon
authors.initials: W
authors.lastname: Lee-Kwon
authors.forename: Erik P
authors.initials: EP
authors.lastname: Silldorff
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Pallone
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000187:drug effects / Q000502:physiology*; D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D025802:Electric Capacitance; D019332:Endothelin-1 / Q000494:pharmacology; D005905:Glyburide / Q000494:pharmacology; D007606:Juxtaglomerular Apparatus / Q000502:physiology*; D054086:KATP Channels; D008564:Membrane Potentials / Q000187:drug effects; D020286:Pericytes / Q000502:physiology*; D020110:Pinacidil / Q000037:antagonists & inhibitors; D024661:Potassium Channels, Inwardly Rectifying / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014667:Vasopressins / Q000494:pharmacology; D000099161:Kcnj11 Channel
chemical_list: D018528:ATP-Binding Cassette Transporters; D000804:Angiotensin II; D019332:Endothelin-1; D005905:Glyburide; D054086:KATP Channels; D020110:Pinacidil; D024661:Potassium Channels, Inwardly Rectifying; D014667:Vasopressins; D000099161:Kcnj11 Channel; C092520:uK-ATP-1 potassium channel