Sl. Amaral et al., Exercise training normalizes wall-to-lumen ratio of the gracilis muscle arterioles and reduces pressure in spontaneously hypertensive rats, J HYPERTENS, 18(11), 2000, pp. 1563-1572
Citations number
39
Categorie Soggetti
Cardiovascular & Respiratory Systems","Cardiovascular & Hematology Research
Objective To investigate mechanisms underlying the training-induced blood p
ressure-lowering effect we analyzed the hemodynamic responses and morphomet
ric changes of the skeletal muscle microcirculation of spontaneously hypert
ensive (SHR) and normotensive Wistar-Kyoto (WKY) rats during an exercise tr
aining program.
Design Training (50-60% VO2 max) was performed on a treadmill for 13 weeks
and control groups were kept sedentary over the same period of time. Traine
d and sedentary rats were chronically instrumented for hindlimb flow and ar
terial pressure (AP) recordings under conscious unrestrained conditions. Gr
acilis and myocardial muscle samples were obtained for morphometric analysi
s after transcardiac perfusion of fixative.
Results SHR, when compared to WKY presented an elevated blood pressure, an
increased relative hindlimb vascular resistance, capillary rarefaction in b
oth gracilis and myocardium and an increased wall-to-lumen ratio of gracili
s arterioles. Training increased significantly both capillary density and c
apillary/fiber ratio in the gracilis and myocardium of WKY and SHR groups,
causing a complete reversal of capillary rarefaction in trained SHR, In SHR
, training also reduced resting blood pressure and caused normalization of
both relative hindlimb vascular resistance and gracilis arterioles wall-to-
lumen ratio, Regression analysis revealed strong positive correlation betwe
en hindlimb vascular resistance and mean AP (MAP) and between arterioles wa
ll-to-lumen ratio and MAP.
Conclusions The results suggest that low-intensity training can significant
ly reduce pressure in SHR while normalizing both the arteriole morphology a
nti the resistance of the skeletal muscle microcirculation. J Hypertens 18:
1563-1572 (C) 2000 Lippincott Williams & Wilkins.