Angiotensin II inhibition increases diuresis during acute sympathetic activation in intact and denervated kidneys in rats with chronic myocardial infarction

We examined urine excretion during primary acute sympathetic activation (PASA) in Wistar–Kyoto rats with myocardial infarction (MI). The rats underwent unilateral renal denervation (RDN) 7 weeks after coronary artery ligation. 4–10 days later, an acute experiment was performed under anesthetized conditions ( n = 8 rats). Isolated carotid sinus pressure was changed stepwise from 60 to 180 mmHg, and the relationship between the arterial pressure (AP) and the normalized urine flow (nUF, urine flow normalized by the body weight) was examined. After obtaining the control data, an angiotensin II type 1 receptor blocker telmisartan (2.5 mg/kg) was intravenously administered. The effects of RDN, telmisartan, and heart weight (biventricular weight) on the relationship between AP and nUF were examined using multiple regression analyses. Regarding the slope of nUF versus AP (nUF slope ), the constant term of the regression was positive (0.315 ± 0.069 μL·min −1 ·kg −1 ·mmHg −1 ), indicating that nUF increased with AP. The heart weight had a negative effect on nUF slope ( P