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

Department of Pharmacology and Toxicology, Boonshoft School of Medicine of Wright State University, Dayton, Ohio Submitted 27 January 2006 ; accepted in final form 18 April 2007 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 AT 1a receptors in the development of fructose-induced cardiovascular and metabolic dysfunction. Male angiotensin AT 1a 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 mmHg 2 , variance, and 7 ± 2 vs. 17 ± 3 mmHg 2 , LF, control vs. fructose, P < 0.004). There were no changes in SAP variance in AT1aKO mice. Depressor responses to 1 -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 AT 1a receptors, a fructose diet decreased blood pressure. blood pressure; heart rate; autonomic nervous system; insulin; spectral analysis; insulin resistance; diabetes Address for reprint requests and other correspondence: M. Morris, Dept. of Pharmacology and Toxicology, Wright State Univ. School of Medicine, 3640 Colonel Glenn Hwy, Dayton, OH 45435 (e-mail: mariana.morris{at}wright.edu )