A high-fat, refined-carbohydrate diet affects renal NO synthase protein expression and salt sensitivity

Abstract

Chronic consumption of a high-fat, refined-carbohydrate (HFS) diet causes hypertension. In an earlier study, we found increased nitric oxide (NO) inactivation by reactive oxygen species (ROS) and functional NO deficiency in this model. Given the critical role of NO in renal sodium handling, we hypothesized that diet-induced hypertension may be associated with salt sensitivity. Female Fischer rats were fed an HFS or a standard low-fat, complex-carbohydrate (LFCC) rat chow diet starting at 2 mo of age for 2 yr. Arterial blood pressure, renal neuronal NO synthase (nNOS), endothelial NO synthase (eNOS), and inducible NO synthase (iNOS) protein and nitrotyrosine abundance (a marker of NO inactivation by ROS), and urinary NO metabolite excretion were measured. To assess salt sensitivity, the blood pressure response to a high-salt (4%) diet for 1 wk was determined. After 2 yr, renal nNOS and urinary NO metabolite excretion were significantly depressed, whereas arterial pressure, eNOS, iNOS, and nitrotyrosine were elevated in the HFS group but remained virtually unchanged in the LFCC group. Consumption of the high-salt diet resulted in a significant rise in arterial pressure in the HFS, but not in the LFCC, group. Thus chronic consumption of an HFS diet results in hypertension and salt sensitivity, which may be in part due to a combination of ROS-mediated NO inactivation and depressed renal nNOS protein expression.