Targeted Genomic Disruption of H-Ras Induces Hypotension Through a NO-cGMP-PKG Pathway–Dependent Mechanism

Abstract—The aim of the present experiments was to evaluate the differences in arterial pressure between H-Ras lacking mice and control mice and to analyze the mechanisms involved in the genesis of the differences. H-Ras lacking mice and mouse embryonic fibroblasts from these animals were used. Blood pressure was measured using 3 different methods: direct intraarterial measurement in anesthetized animals, tail-cuff sphygmomanometer, and radiotelemetry. H-Ras lacking mice showed lower blood pressure than control animals. Moreover, the aorta protein content of endothelial nitric oxide synthase, soluble guanylyl cyclase, and cyclic guanosine monophosphate–dependent protein kinase was higher in H-Ras knockout mice than in control animals. The activity of these enzymes was increased, because urinary nitrite excretion, sodium nitroprusside–stimulated vascular cyclic guanosine monophosphate synthesis, and phosphorylated vasoactive-stimulated phosphoprotein in aortic tissue increased in these animals. Furthermore, mouse embryonic fibroblasts from H-Ras lacking mice showed higher cyclic guanosine monophosphate–dependent protein kinase promoter activity than control cells. These results strongly support the upregulation of the nitric oxide-cyclic guanosine monophosphate pathway in H-Ras–deficient mice. Moreover, they suggest that H-Ras pathway could be considered as a therapeutic target for hypertension treatment. (Hypertension. 2010;56:484-489.) Key Words: arterial pressure H-Ras protein nitric oxide cyclic GMP soluble guanylyl cyclase cGMP-dependent protein kinas