ラットにおける高所滞在・平地トレーニングが肺循環動態および肺動脈の血管内皮型一酸化窒素合成酵素タンパク質発現に与える影響 EFFECTS OF "LIVING HIGH AND TRAINING LOW" ON PULMONARY CIRCULATION HEMODYNAMICS AND ENDOTHELIAL NITRIC OXIDE SYNTHASE PROTEIN EXPRESSION IN PULMONARY ARTERY OF RATS

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.