Elevated body temperature and increased blood vessel sensitivity in spontaneously hypertensive rats
Price, J.M.; Wilmoth, F.R.
American Journal of Physiology 258(4 Pt 2): H946-H953
1990
ISSN/ISBN: 0002-9513 PMID: 2331018 Document Number: 348236
Body temperature (BT) was significantly greater in spontaneously hypertensive rats (SHR) than in Wistar-Kyoto (WKY) rats regardless of the time of day, length of rectal probe, sex, age, or commercial vendor. Bath temperature (.theta.) for excised aortic rings was controlled by a thermoelectric Peltier module with an accuracy of 0.1.degree.C. At peak force in individual contractions of norepinephrine (NE) dose-response experiments, .theta. was changed from 37 to 39.degree.C. Active and resting wall tension (Tw) were increased, and the mean effective dose (ED50) was decreased in the SHR aorta with and without endothelium. For the WKY aorta, active and resting Tw were increased, but ED50 was the same with and without endothelium. These results were supported by experiments where .theta. was decreased from 39 to 37.degree.C and by experiments on Spraque-Dawley rats. Potassium dose-response experiments with aorta from SHR and WKY rats show an increase in sensitivity at 39.degree.C, but active Tw is the same at 39 and 37.degree.C. When compared at the BT of each rat, the NE ED50 was lower and resting Tw was the same. The results suggest that 1) the SHR aorta is more sensitive to NE than the WKY aorta at the rat's respective body temperatures, 2) this difference is due to a dependence of sensitivity of the aorta on temperature and to the higher body temperature of the SHR, 3) the greater resting wall tension in the SHR aorta is due in part to a temperature-dependent active tone and to the higher body temperature of SHR, and 4) the dependence of sensitivity on temperature in the SHR does not involve the endothelium or the NE receptor.