Genetic and dietary interactions: role of angiotensin AT1a receptors in response to a high-fructose diet

Abstract

The renin-angiotensin system (RAS) has been implicated in the cardiovascular complications of diabetes. We showed that a high-fructose diet increases blood pressure and plasma angiotensin and impairs glucose tolerance. We investigated the role of angiotensin AT1a receptors in the development of fructose-induced cardiovascular and metabolic dysfunction. Male angiotensin AT1a knockout (AT1aKO) and wild-type (AT1aWT) mice with arterial telemetric catheters were fed a standard diet or one containing 60% fructose. Fructose increased mean arterial pressure (MAP) in AT1aWT but only during the dark phase (8% increase). In AT1aKO mice, fructose unexpectedly decreased MAP, during both light and dark periods (24 and 13% decrease, respectively). Analytical methods were used to measure systolic arterial pressure (SAP) and pulse interval (PI) variability in time and frequency domains. In fructose-fed AT1aWT mice, there was an increase in SAP variance and its low-frequency (LF) domain (11 ± 3 vs. 23 ± 4 mmHg2, variance, and 7 ± 2 vs. 17 ± 3 mmHg2, LF, control vs. fructose, P < 0.004). There were no changes in SAP variance in AT1aKO mice. Depressor responses to α1-adrenergic blockade were augmented in fructose-fed AT1a WT compared with AT1aKO mice. Fructose inhibited glucose tolerance with a greater effect in AT1aWT mice. Fructose increased plasma cholesterol in both groups ( P < 0.01) and reduced ANG II in AT1aKO mice. Results document prominent interactions between genetics and diet with data showing that in the absence of angiotensin AT1a receptors, a fructose diet decreased blood pressure.