Renal angiotensin II AT2 receptors promote natriuresis in streptozotocin-induced diabetic rats

doi:10.1152/ajprenal.00092.2005.— Angiotensin II AT2 receptors have been implicated to play a role in the regulation of renal/cardiovascular functions under pathological condi-tions. The present study is designed to investigate the function of the AT2 receptors on renal sodium excretion and AT2 receptor expression in the cortical membranes of streptozotocin (STZ)-induced diabetic rats. The STZ treatment led to a significant weight loss, hyperglycemia, and decrease in plasma insulin levels compared with control rats. STZ-induced diabetic rats had significantly elevated basal urine flow, urinary sodium excretion rate (UNaV), urinary fractional sodium excretion, and urinary cGMP compared with control rats. Infusion of PD-123319, an AT2 receptor antagonist, caused a significant decrease in UNaV (mol/ min) in STZ-induced diabetic rats (1 0.09 vs. 0.45 0.1) but not in control rats (0.35 0.05 vs. 0.4 0.07). The decrease in UNaV was associated with a significant decrease in urinary cGMP levels (pmol/min