Effects of resistance training on changes in vascular reactivity and morphology of L-NAME induced hypertensive rats

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.A hipertensão arterial (HA) é uma síndrome multifatorial, crônica, causada tanto por fatores congênitos ou adquiridos, como a inatividade física. Avaliar os efeitos do treinamento físico resistido (TR) sobre pressão arterial, reatividade vascular e morfologia da artéria mesentérica superior de ratos hipertensos. Ratos Wistar machos (200-250 g) foram divididos em 3 grupos: normotenso sedentário (NS), hipertenso sedentário (HS) e hipertenso treinado (HT). HA foi induzida pela administração de L-NAME (40 mg/kg) na água de beber por 4 semanas. Após o TR, a pressão arterial, reatividade vascular para nitroprussiato de sódio e fenilefrina (FEN) foram avaliados. Além disso, foram realizadas análises histológica e estereológica dos segmentos arteriais. O TR inibiu o aumento da PAM, PAS e PAD. Foi observada uma redução significativa (p<0,01) na potência da FEN do grupo HT quando comparado com o HS (5,34±0,12 vs 6,01±0,11). A análise histológica dos segmentos arteriais evidenciou aspecto normal para as túnicas íntima, média e adventícia em todos os grupos. Não houve diferença significativa nas áreas do lúmen, da túnica média e total das artérias dos grupos HS e HT em relação ao NS. A razão parede/lúmen arterial do grupo HT não apresentou diferença significativa em relação ao HS (p