Increased Nitric Oxide Bioavailability in Adult GRK2 Hemizygous Mice Protects Against Angiotensin II–Induced Hypertension

Abstract

G protein-coupled receptor kinase 2 (GRK2) is a ubiquitous serine/threonine protein kinase able to phosphorylate and desensitize the active form of several G protein-coupled receptors. Given the lack of selective inhibitors for GRK2, we investigated the effects elicited by GRK2 inhibition in vascular responses using global adult hemizygous mice (GRK2(+/-)). The vasodilator responses to acetylcholine or isoproterenol were increased in aortas and mesenteric resistance arteries from GRK2(+/-) mice compared with wild-type (WT) littermates. After angiotensin II (AngII) infusion, GRK2(+/-) mice were partially protected against hypertension, vascular remodeling, and mechanical alterations, even when resting basal blood pressures were not significantly different. AngII infusion also (1) increased GRK2 levels in WT but not in GRK2(+/-) vessels; (2) increased vasoconstrictor responses to phenylephrine in WT but not in GRK2(+/-) mice; and (3) decreased vasodilator responses to acetylcholine and vascular pAkt and eNOS levels more in WT than in GRK2(+/-) animals. Vascular NO production and the modulation of vasoconstrictor responses by endothelial-derived NO remained enhanced in GRK2(+/-) mice infused with AngII. Thus, GRK2(+/-) mice are resistant to the development of vascular remodeling and mechanical alterations, endothelial dysfunction, increased vasoconstrictor responses, and hypertension induced by AngII at least partially through the preservation of NO bioavailability. In conclusion, our results describe an important role for GRK2 in systemic hypertension and further establish that an inhibition of GRK2 could be a beneficial treatment for this condition.