This study examined the cardiovascular, renal, and hormonal responses of di
etary-induced obesity in Osborne-Mendel (OM) rats. Male OM rats were fed ei
ther a low (LF; n = 10)- or high-fat (HF; n = 11) diet for 17 wk. During we
ek 15 of the study, arterial pressure was measured directly, 24 h/day, from
chronically indwelling catheters. Body and kidney weights were 46 +/-5 and
33 +/-5% greater, respectively, in rats fed HF vs. LF diet. Left and right
ventricular weights were also greater in rats fed HF diet (21 +/-7 and 36
+/-6%, respectively). Direct measurement of arterial pressure revealed only
a slight increase in mean arterial pressure (88 +/-1 in rats fed HF diet v
s. 85 +/-1 mmHg in rats fed LF diet), whereas there was no difference in re
sting heart rate between the two groups. Consumption of HF diet was also as
sociated with a 3.5-fold increase in plasma insulin, a 16 +/-4% higher bloo
d glucose, and a 40 +/-6% reduction in plasma renin activity compared with
LF-fed rats. Thus feeding OM rats HF diet led to obesity, cardiac and renal
hypertrophy, and hyperinsulinemia but only a slight increase in mean arter
ial pressure.