RESUMO
The present study was to evaluate endothelial nitric oxide synthase (eNOS) protein expression and hemodynamics of pulmonary circulation in rats of "Living high and Training low" (LH+TL). The Sprague Dawley strain of male rats were used at the age of 9 weeks. They were divided according to four conditions of a living low (LL) group, living low and training low (LL+TL) group, living high (LH) group and LH+TL group, for 10 days. We assessed the effects of LH+TL on exercise-induced pulmonary arterial pressure and blood lactic acids under sea-level altitude in catheter-implanted conscious rats. Also, we measured the pulmonary artery under anesthesia and analyzed eNOS protein expression by western blot analysis. The blood lactate levels in the LH+TL rats decreased after maximal treadmill running compared to LL, LL+TL and LH rats (p<0.05). The increase in pulmonary arterial blood pressure with exercise was significantly lower in the LH+TL group than in the LL group (p<0.05). The eNOS protein expressions of pulmonary artery were higher in the LH+TL group than in the LL group (p<0.05). This study indicates that LH+TL reduced the increase of pulmonary arterial blood pressure with exercise at below sea-level altitude. In addition, eNOS protein expressions were enhanced in the pulmonary arteries of LH+TL rats. Thus, we conclude that the high altitude training of LH+TL was a useful method for improvement of endurance exercise ability and this improvement may be associated with pulmonary arterial response.