Effects of low sodium diet and unilateral nephrectomy on the development of carbohydrate-induced hypertension

Since there appear to be important interactions between mechanisms of salt-sensitive and carbohydrate-sensitive hypertension, the goal of this study was to evaluate the effects of greatly reducing dietary salt intake and removal of one kidney (to increase salt sensitivity) on the hemodynamic and metabolic responses to carbohydrate-enriched diets in three different rat strains. All three strains of laboratory rat developed significant increases in fasting plasma insulin (1-2 fold, p < 0.03) and triglyceride (2-3 fold, p < 0.01) concentrations in response to fructose (or sucrose) enriched diets, irrespective of salt content. Blood pressure increased significantly in response to carbohydrate feeding in both Sprague-Dawley (S-D) and Dahl salt-sensitive rats, but not in Fischer 344 rats, and decreasing salt intake had no effect on the development of carbohydrate-induced hypertension: e.g., delta BP in S-D rats was +20 mmHg after the fructose-0.5% NaCl diet as compared with +19 mmHg after fructose-0.02% NaCl, and delta BP in Dahl salt-sensitive rats was +22 mmHg after fructose-0.02% NaCl. Finally, nephrectomy neither accentuated the degree of hypertension in fructose-fed S-D rats, nor increased blood pressure in fructose-fed Fischer 344 rats. These results emphasize the strain specific characteristics of carbohydrate-induced hypertension in rats, and indicate that the hemodynamic responses of different rat strains to dietary carbohydrate are not modified by either decreasing salt intake or removing one kidney.