Hypertension in Obese Zucker Rats

Abstract

We designed our studies to determine whether blood pressure is elevated in obese Zucker rats compared with lean control rats and to test the importance of the renin-angiotensin and adrenergic nervous systems in long-term blood pressure control in this genetic model of obesity. We monitored mean arterial pressure 24 hours per day using computerized methods in 13- to 14-week-old lean and obese Zucker rats maintained on a fixed, normal sodium intake (3.3 mmol/d). Mean arterial pressure (average of 5 days) was higher in obese (100±1 mm Hg) than in lean (86±1) rats. Although control plasma renin activity was lower in obese than in lean rats (3.66±0.15 versus 5.48±0.11 ng angiotensin I/mL per hour), blood pressure sensitivity to exogenous angiotensin II was greater in obese than in lean rats. Blockade of endogenous angiotensin II receptors with losartan (10 mg/kg per day) for 7 days also caused a greater decrease in blood pressure in obese (36±2 mm Hg, n=6) than in lean (25±1, n=5) rats. However, combined α- an...