Microvascular alterations in adult conscious spontaneously hypertensive rats.
The dorsal skin flap technique was used to study skeletal muscle microcirculation in conscious 10-12-week-old spontaneously hypertensive rats and normotensive Wistar-Kyoto control rats. Videorecordings were made for off-line analysis of consecutive segments of the vascular bed. Resting diameters were significantly smaller in spontaneously hypertensive rats than in Wistar-Kyoto rats at the first-order (-28%) and second-order arteriolar (-21%) levels. Precapillary third-order and fourth-order arterioles of spontaneously hypertensive rats had normal diameters, whereas postcapillary small venule diameters were slightly larger in spontaneously hypertensive rats. Thirty percent and 41% of the spontaneously hypertensive rat and Wistar-Kyoto rat third-order arteriolar vessels and 63 and 45% of the fourth-order arteriolar vessels exhibited vasomotion. Vasomotion amplitude, but not frequency, was significantly higher in spontaneously hypertensive rats than in Wistar-Kyoto rats. It is concluded that, in the established phase of spontaneous hypertension in the rat, a decreased diameter of large arterioles is the major mechanism underlying the increased vascular resistance in cutaneous skeletal muscle.
le Noble
J L
JL
Department of Internal Medicine, University of Limburg, Maastricht, The Netherlands.
Smith
T L
TL
Hutchins
P M
PM
Struyker-Boudier
H A
HA
D000818:Animals; D001808:Blood Vessels / Q000033:anatomy & histology; D008833:Microcirculation; D051381:Rats; D011918:Rats, Inbred SHR / Q000033:anatomy & histology*; D011919:Rats, Inbred Strains / Q000033:anatomy & histology*; D011921:Rats, Inbred WKY; D014666:Vasomotor System / Q000502:physiology