Effects of food restriction on mechanical properties of arterial system in adult and middle-aged rats

Abstract

The effects of food restriction on the mechanical properties of the vasculature were determined in Long-Evans male rats with different ages. Rats that began food restriction at the ages of 6 months and 12 months were fed on alternate days for 6 months. Rats at the ages of 12 and 18 months were referred to as adult and middle-aged rats and were anesthetized and thoracotomized. The exponentially tapered T-tube model was employed to relate pulsatile pressure and flow signals measured in the ascending aorta. In each age group, food restriction elicited a decrease in body weight as well as basal heart rate but showed no significant change in cardiac output. Arterial blood pressure, total peripheral resistance, and aortic characteristic impedance were not affected by food restriction in middle- aged rats. However, adult food-restricted rats exhibited lower mean arterial blood pressure (99.1 ± 3.1 mmHg) than did adult ad libitum-fed rats (110.7 ± 3.0 mmHg). Total peripheral resistance was reduced from 0.645 ± 0.045 mmHg-min-kg/ml in adult ad libitum-fed rats to 0.492 ± 0.030 mmHg-min-kg/ml in adult food-restricted rats. Moreover, aortic characteristic impedance of adult food-restricted rats (0.014 ± 0.001 mmHg-min-kg/ml) was lower than that of adult ad libitum-fed rats (0.024 ± 0.002 mmHg-min-kg/ml). Neither age nor diet exerted effects on wave transit time and produced no changes in aortic distensibity. In conclusion, food restriction may elicit significant changes in the mechanical properties of both Windkessel vessels and resistance arterioles in adult rats, but not in middle-aged rats.