Some Aspects of Role of Nitric Oxide in the Mechanisms of Hypertension (Experimental Study)

BACKGROUND: Modulation of endothelial function is a therapeutic option to reduce some of the significant complications of hypertension. However, the relationship between endothelial dysfunction reduced nitric oxide (NO) production, and the development of hypertension is not fully understood. To establish a potential pathogenetic link between impaired NO synthesis and hypertension, we investigated the results of competitive interaction of the substrate of NO synthase, L-arginine, and its analog, an non-selective inhibitor of NO synthase, N-nitro-methyl ether-L-arginine (L-NAME), in experimental rats. METHODS: Arterial hypertension was induced in male Wistar rats by intraperitoneal administration of L-NAME (Sigma-Aldrich) for 4 - 7 weeks. During the last 3 weeks, to a separate group of animals simultaneously with L-NAME, L-arginine (Sigma-Aldrich) was administered. In animals monitored for systolic and diastolic pressure, the level of NO in blood samples was determined spectrophotometrically using a Griess reagent. RESULTS: Administration of L-NAME for 4 - 7 weeks induced an irreversible decrease of NO content in blood, a reversible increase of systolic pressure (SP) and diastolic pressure (DP), and an irreversible increase in pulse pressure (PP). In rats against the background of 7 weeks of intraperitoneal administration of L-NAME, during the last 3 weeks, they were injected with L-arginine, the SP and DP indices returned to their initial values, PP decreased and the NO content in arterial blood increased. CONCLUSIONS: The results of the study indicate the presence of residual endothelial dysfunction (characterized by insufficient NO) after the correction of hypertension. Therefore, in developing the new therapeutic approaches for the treatment of hypertension, it is necessary to include drugs that, in addition to correcting blood pressure, will support normalization, and potentiation of endothelial function and endogenous NO synthesis.