Angiotensin II regulates oxygen consumption

Previous studies demonstrated that angiotensin II (ANG II) decreases body weight. This study examined whether ANG II regulates body weight through energy expenditure. Acute ANG II administration decreased oxygen consumption. To determine whether this effect was maintained, rats were infused with ANG II or saline for 14 days. Oxygen consumption was transiently decreased on day 1 of ANG II infusion; however, body weight and food intake were reduced for 14 days. In pair-feeding studies, reductions in food intake accounted for 63% of the effect of ANG II on body weight but did not influence systolic pressure, water intake, or oxygen consumption. With 28 days of ANG II infusion, differences in body weight between ANG II and control rats were of greater magnitude. An initial decrease in oxygen consumption was followed by a rebound increase. Coadministration of losartan prevented the effect of ANG II on body weight, food intake, blood pressure, and water intake. However, losartan only partially prevented ANG II reductions in oxygen consumption. These results demonstrate that ANG II transiently decreases oxygen consumption through mechanisms unrelated to food intake. With chronic ANG II exposure, energy expenditure may contribute to sustained reductions in body weight.