ANG II signaling in vasa recta pericytes by PKC and reactive oxygen species

Abstract

ANG II constricts descending vasa recta (DVR) through Ca(2+) signaling in pericytes. We examined the role of PKC DVR pericytes isolated from the rat renal outer medulla. The PKC blocker staurosporine (10 microM) eliminated ANG II (10 nM)-induced vasoconstriction, inhibited pericyte cytoplasmic Ca(2+) concentration ([Ca(2+)](cyt)) elevation, and blocked Mn(2+) influx into the cytoplasm. Activation of PKC by either 1,2-dioctanoyl-sn-glycerol (10 microM) or phorbol 12,13-dibutyrate (PDBu; 1 microM) induced both vasoconstriction and pericyte [Ca(2+)](cyt) elevation. Diltiazem (10 microM) blocked the ability of PDBu to increase pericyte [Ca(2+)](cyt) and enhance Mn(2+) influx. Both ANG II- and PDBu-induced PKC stimulated DVR generation of reactive oxygen species (ROS), measured by oxidation of dihydroethidium (DHE). The effect of ANG II was only significant when ANG II AT(2) receptors were blocked with PD-123319 (10 nM). PDBu augmentation of DHE oxidation was blocked by either TEMPOL (1 mM) or diphenylene iodonium (10 microM). We conclude that ANG II and PKC activation increases DVR pericyte [Ca(2+)](cyt), divalent ion conductance into the cytoplasm, and ROS generation.

β1 Receptors Protect the Renal Afferent Arteriole of Angiotensin-Infused Rabbits from Norepinephrine-Induced Oxidative Stress

“…Tempol fully prevents the graded vasoconstriction of isolated, perfused Aff to the O 2 ⅐ Ϫ -generating quinolone paraquat (19). Studies with fluorescence indicators of O 2 ⅐ Ϫ have confirmed that tempol, in the dosage used in this study, fully prevents the generation of O 2 ⅐ Ϫ in isolated, perfused vasa recta that are stimulated with AngII (27). This was confirmed in this study, in which enhanced vascular O 2 ⅐ Ϫ generation by NE during ␤ 1 -adrenergic receptor blockade was normalized by bath addition of 10 Ϫ4 M tempol.…”

Microvascular Effects of Aldosterone and Angiotensin Type 2 Receptors

“…In that preparation, AT2R activation increases NO bioavailability by inhibiting generation of reactive oxygen species. 17,19 Taken together, the finding by Gonzales et al 1 that AT2R activation is vasodilatory largely supports previous observations.…”

Redox Control of Renal Function and Hypertension

“…NAD(P)H oxidase, as well as other metabolic oxidases such as xanthine oxidase and mitochondrial respiratory chain enzymes (I-IV), are functional in the kidney (278). However, we and others have identified NAD(P)H oxidase-induced ROS production as a primary initiator of oxidative stress within the kidney (183,353,355,356 onists that bind to D1-like receptors, and to H ϩ fluxes (28,89,146,184,259,353,377,384) (Figs. 6 through 9).…”