The tissue renin-angiotensin system in rats with fructose-induced hypertension: overexpression of type 1 angiotensin II receptor in adipose tissue

Objective Fructose feeding induces hypertension, insulin-resistance and hyp ertriglyceridemia in Sprague-Dawley rats. The mechanisms of fructose-induce d hypertension are as yet unknown. Here we investigate the effects of fruct ose feeding and of varying salt intake on blood pressure, glucose tolerance , plasma renin activity, and tissue angiotensinogen, renin, and AT(1) recep tor mRNA levels in this model of hypertension. Design and methods To investigate the role of the renin-angiotensin system in fructose-induced hypertension we measured angiotensinogen, renin and ang iotensin II type 1 (AT(1)) receptor mRNA levels in tissues of Sprague-Dawle y rats that were fed either standard rat chow or a diet containing 66% fruc tose. Results Blood pressure (P < 0.05) and triglyceride (P < 0.01) levels were s ignificantly greater in the fructose-fed animals. Plasma glucose and insuli n responses to an oral glucose load were significantly greater (P < 0.05) i n fructose-fed than control rats. Angiotensinogen mRNA levels in liver and fat, and renin mRNA levels in kidney did not differ between fructose-fed an d control animals. Levels of AT(1) receptor mRNA were significantly greater in the fat obtained from fructose-fed rats than in that from control rats (P < 0.05), but this was not so in the kidney. To determine whether fructos e-induced hypertension is dependent on dietary salt content, rats were fed standard rat chow and a fructose-enriched diet with low and high sodium chl oride concentrations. Blood pressure increased significantly (P < 0.05) onl y in the fructose-fed rats receiving the high-salt diet. Similarly, increas ed AT(1) receptor mRNA levels were observed only in the fructose-fed rats t hat were maintained on the high-salt diet Conclusions Fructose feeding induces hypertension in normal- or high-salt f ed animals and it is associated with an increased expression of the AT(1) r eceptor in adipose tissue. These findings suggest that AT(1) receptors migh t play a role in the pathophysiology of metabolic and hemodynamic abnormali ties induced by fructose feeding. J Hypertens 2000, 18:695-702 (C) Lippinco tt Williams & Wilkins.