Abstract-Evidence of mild hypertension in women and female rats and our preliminary observation showing that training is not effective to reduce pressure in female as it does in male spontaneously hypertensive rats (SHR) prompt us to investigate the effects of gender on hemodynamic pattern and microcirculatory changes induced by exercise training. Female SHR and normotensive controls (Wistar-Kyoto rats) were submitted to training (55% VO 2 peak; 3 months) or kept sedentary and instrumented for pressure and hindlimb flow measurements at rest and during exercise. Heart, kidney, and skeletal muscles (locomotor/nonlocomotor) were processed for morphometric analysis of arterioles, capillaries, and venules. High pressure in female SHR was accompanied by an increased arteriolar wall:lumen ratio in the kidney (ϩ30%; PϽ0.01) but an unchanged ratio in the skeletal muscles and myocardium. Female SHR submitted to training did not exhibit further changes on the arteriolar wall:lumen ratio and pressure, showing additionally increased hindlimb resistance at rest (ϩ29%; PϽ0.05). On the other hand, female SHR submitted to training exhibited increased capillary and venular densities in locomotor muscles (ϩ50% and 2.3-fold versus sedentary SHR, respectively) and normalized hindlimb flow during exercise hyperemia. Left ventricle pressure and weight were higher in SHR versus WKY rats, but heart performance (positive dP/dt max and negative dP/dt max ) was not changed by hypertension or training, suggesting a compensated heart function in female SHR. In conclusion, the absence of training-induced structural changes on skeletal muscle and myocardium arterioles differed from changes observed previously in male SHR, suggesting a gender effect. This effect might contribute to the lack of pressure fall in trained female SHRs. Key Words: skeletal muscle Ⅲ myocardium Ⅲ kidney Ⅲ arterioles Ⅲ capillaries Ⅲ venules Ⅲ vascular resistance H ypertension is the most important risk factor for cardiovascular disease in developed countries, affecting approximately one third of adults and elderly people of both sexes. 1,2 Although several clinical trials using different antihypertensive drugs showed significant reductions in pressure and cardiovascular morbidity and mortality, 1 the age-adjusted death rate from hypertension in men and women has been shown to increase in the United States in the last decade. 1-3 It is known that gender affects hypertension. High-pressure levels are less prevalent in young women (premenopause) compared with age-matched men 1,3-5 but of similar prevalence in elderly women. 4,6 Regular aerobic exercise, other than several antihypertensive treatments available, was shown to be an important therapeutic tool, causing significant pressure fall in hypertensive patients and animals. 1,5,[7][8][9] Exercise-induced reductions in vascular resistance, 10,11 cardiac output, 12 insulin resistance, 13 and sympathetic activity 14,15 have been associated with pressure fall. There is no clear information as to whether gender affects train...

Exercise-induced vessel changes modulate arterial pressure (AP) in male spontaneously hypertensive rats (SHR). Vascular endothelial growth factor (VEGF) is important for angiogenesis of skeletal muscle. The present study evaluated the time course of VEGF and angiogenesis after short-and long-term exercise training of female SHR and Wistar Kyoto (WKY) rats, 8-9 weeks (200-250 g). Rats were allocated to daily training or remained sedentary for 3 days (N = 23) or 13 weeks (N = 23). After training, the carotid artery was catheterized for AP measurements. Locomotor (tibialis anterior and gracilis) and non-locomotor skeletal muscles (temporalis) were harvested and prepared for histologic and protein expression analyses. Training increased treadmill performance by all groups (SHR = 28%, WKY = 64%, 3 days) and (SHR = 141%, WKY = 122%, 13 weeks). SHR had higher values of AP than WKY (174 ± 4 vs 111 ± 2 mmHg) that were not altered by training. Three days of running increased VEGF expression (SHR = 28%, WKY = 36%) simultaneously with an increase in capillary-to-fiber ratio in gracilis muscle (SHR = 19%, WKY = 15%). In contrast, 13 weeks of training increased gracilis capillary-to-fiber ratio (SHR = 18%, WKY = 19%), without simultaneous changes in VEGF expression. Training did not change VEGF expression and capillarity of temporalis muscle. We conclude that training stimulates time-and tissue-dependent VEGF protein expression, independent of pressure levels. VEGF triggers angiogenesis in locomotor skeletal muscle shortly after the exercise starts, but is not involved in the maintenance of capillarity after long-term exercise in female rats.

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