Excessive Zinc Intake Increases Systemic Blood Pressure and Reduces Renal Blood Flow via Kidney Angiotensin II in Rats

This study investigated the effects of excess zinc intake on the mean arterial pressure (MAP), renal blood flow (RBF), inulin clearance (IC), serum zinc level, serum angiotensin-converting enzyme (ACE) activity, and kidney angiotensin II (AT II) levels in rats. Experiments were performed on male Sprague–Dawley rats maintained for 4 weeks on a diet containing either 5 mg/100 g (control group), 50 mg/100 g (Zn50 group), or 200 mg/100 g (Zn200 group) zinc carbonate. Serum zinc levels significantly increased to 126.5 % in the Zn50 group and 198.1 % in the Zn200 group compared with controls. MAP significantly increased to 107.8 % in the Zn50 group and 114.5 % in the Zn200 group again compared with controls. Although the difference in serum ACE activity was independent of the serum zinc levels, the kidney AT II levels increased significantly to 137.2 % in the Zn50 group and 174.4 % in the Zn200 group compared with the controls. RBF was decreased significantly to 74.4 % in the Zn50 group and 69.7 % in the Zn200 group compared with the controls. IC values were significantly decreased to 69.6 % in the Zn50 group and 52.7 % in the Zn200 group as compared with control levels. Combined together, these results show that excessive Zn intake reduced IC and RBF and increased MAP and kidney AT II levels, suggesting that excessive Zn intake reduces renal function.