title: Angiotensin II stimulates basolateral 50-pS K channels in the thick ascending limb.
abstract: We used the patch-clamp technique to examine the effect of angiotensin II (ANG II) on the basolateral K channels in the thick ascending limb (TAL) of the rat kidney. Application of ANG II increased the channel activity and the current amplitude of the basolateral 50-pS K channel. The stimulatory effect of ANG II on the K channels was completely abolished by losartan, an inhibitor of type 1 angiotensin receptor (AT1R), but not by PD123319, an AT2R antagonist. Moreover, inhibition of phospholipase C (PLC) and protein kinase C (PKC) also abrogated the stimulatory effect of ANG II on the basolateral K channels in the TAL. This suggests that the stimulatory effect of ANG II on the K channels was induced by activating PLC and PKC pathways. Western blotting demonstrated that ANG II increased the phosphorylation of c-Src at tyrosine residue 416, an indication of c-Src activation. This effect was mimicked by PKC stimulator but abolished by calphostin C. Moreover, inhibition of NADPH oxidase (NOX) also blocked the effect of ANG II on c-Src tyrosine phosphorylation. The role of Src-family protein tyrosine kinase (SFK) in mediating the effect of ANG II on the basolateral K channel was further suggested by the experiments in which inhibition of SFK abrogated the stimulatory effect of ANG II on the basolateral 50-pS K channel. We conclude that ANG II increases basolateral 50-pS K channel activity via AT1R and that activation of AT1R stimulates SFK by a PLC-PKC-NOX-dependent mechanism.
authors.affiliation: Dept. of Pharmacology, New York Medical College, 15 Dana Rd., Valhalla, NY 10595. wenhui_wang@nymc.edu.
authors.forename: Mingxiao
authors.initials: M
authors.lastname: Wang
authors.forename: Haiyan
authors.initials: H
authors.lastname: Luan
authors.forename: Peng
authors.initials: P
authors.lastname: Wu
authors.forename: Lili
authors.initials: L
authors.lastname: Fan
authors.forename: Lijun
authors.initials: L
authors.lastname: Wang
authors.forename: Xinpeng
authors.initials: X
authors.lastname: Duan
authors.forename: Dandan
authors.initials: D
authors.lastname: Zhang
authors.forename: Wen-Hui
authors.initials: WH
authors.lastname: Wang
authors.forename: Ruimin
authors.initials: R
authors.lastname: Gu
mesh_terms: D000804:Angiotensin II / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D005121:Extremities / Q000503:physiopathology*; D019255:NADPH Oxidases / Q000378:metabolism; D018408:Patch-Clamp Techniques / Q000379:methods; D015221:Potassium Channels / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011945:Receptors, Angiotensin / Q000378:metabolism
chemical_list: D015221:Potassium Channels; D011945:Receptors, Angiotensin; D000804:Angiotensin II; D019255:NADPH Oxidases; D011493:Protein Kinase C
keywords: AT1R; Kir.4.1; NOX; Src-family protein tyrosine kinase