Efeitos do treinamento físico resistido na reatividade e morfologia vascular de ratos hipertensos induzidos por L-NAME

Abstract

Arterial hypertension (AH) is a multifactorial chronic syndrome, caused by either congenital or acquired factors such as physical inactivity. To evaluate the effects of Resistance Training (RT) in arterial blood pressure, and in vascular reactivity and morphology of hypertensive rats induced by L-NAME. Male Wistar rats (200 250 g) were allocated into one of the following groups: Sedentary Normotensive (SN), Sendentary Hypertensive (SH) and Trained Hypertensive (TH) groups. To induce hypertension, L-NAME (40 mg/Kg) was given in the drinking water during 4 weeks. Mean arterial pressure (MAP) was evaluated before and after the RT. RT was performed with 50% of 1RM, 3 sets of 10 repetitions, 3 times for week, over 4 weeks. Superior mesenteric artery rings were obtained in order to establish concentration-response curves to sodium nitroprusside (SNP; 10-8 10-4 M) and phenylephrine (PHE; 10-8 10-3 M) as well for histological and stereological analysis. No changes in weight gain were observed at the end of experimental period. Resistance training inhibited the increase in mean, systolic and diastolic arterial pressures. Significative differences were not observed in Rmax (maximal response) and pD2 (potency) for SNP and PHE between SH and TH groups. Arteries demonstrated normal intima, media and adventitia layers in all groups. Stereological analysis demonstrated no significant difference in luminal, tunica media, and total areas of arteries in SH and TH groups when compared to SN. Wall to-lumen ratio of SH arteries was significant different compared to SN (p<0.05), however, not different to TH. Thus, it can be concluded that the RT, under the conditions in this study, was able to control blood pressure. This appears to involve a vasoconstrictor regulation mechanism and maintenance of luminal diameter in LNAME induced hypertensive rats.