Enhanced response of arterioles to oxygen during development of hypertension in SHR.
The goal of this study was to assess the possible role of O2-related local control mechanisms in contributing to an elevated skeletal muscle resistance during the development of hypertension in the spontaneously hypertensive rat (SHR). Diameters of first- (1A), second- (2A), third- (3A), and fourth-order (4A) arterioles were measured by television microscopy in the cremaster muscle of SHR in the early (4- to 6-wk-old) and rapidly developing (8- to 9-wk-old) stages of hypertension and in age-matched normotensive Wistar-Kyoto (WKY) controls. Active neurogenic tone was blocked by superfusing the tissue with 0.1 microgram/ml tetrodotoxin. When superfusion solution PO2 was elevated by changing the gas equilibration mixture from 0 to 5% O2, neurally blocked 3A and 4A of SHR exhibited a significantly greater constriction and a higher incidence of complete closure than those of their age-matched WKY controls. However, there were no significant differences in the constriction of larger arterioles (1A and 2A) in response to elevated superfusion solution PO2. The results suggest that O2-related local control mechanisms could contribute to constriction and closure of small arterioles and to an elevated skeletal muscle vascular resistance early in the development of hypertension in SHR.
J H
JH
Lombard
M E
ME
Hess
W J
WJ
Stekiel
D000818:Animals; D001158:Arteries / Q000187:drug effects*; D001160:Arterioles / Q000187:drug effects*; D001794:Blood Pressure; D006339:Heart Rate; D006973:Hypertension / Q000503:physiopathology*; D008297:Male; D010100:Oxygen / Q000494:pharmacology*; D010313:Partial Pressure; D010477:Perfusion; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D012996:Solutions
D012996:Solutions; D010100:Oxygen