Abstract
Atrial temperature (Tat), heat production (M), mean arterial blood pressure (BP), and feeding (FA) and locomotor (LA) activities were measured over a 24-h period in spontaneously hypertensive rats (SHR) and their normotensive controls (Wistar Kyoto rats; WKY) at an ambient temperature of 24°C. Clear day-night changes in all variables were observed in both groups except for BP and LA in SHR. During the day (0600-1800h), SHR moved more frequently and seemed to eat more food than WKY. However, the total amount of food consumed for the 2 consecutive days was the same in both SHR and WKY. Compared with WKY, average M and BP during the day and at night and FA and LA during the day were significantly higher in SHR. The responses of Tat for a 24-h period, M during the day and for a 24-h period, and BP during the day to FA were significantly enhanced in SHR. There were no such significant differences of responses in Tat, M, and BP to LA between SHR and WKY. The results suggest that SHR is hyper-responsive in metabolism and blood pressure to feeding activity, particularly in the daytime, but not to locomotion.
