低酸素下の最大運動において、運動前の低酸素暴露時間の違いが血漿アンモニア濃度に及ぼす影響

概要

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The purpose of this study was to investigate the effect of a difference in hypoxic exposure duration before exercise on maximum plasma ammonia concentrations at maximal exercise in hypoxia. On three occasions, seven healthy male subjects performed an incremental exhaustive exercise on a cycle ergometer ; 1) Inhaling 12% O_2 from 60min before exercise to 10 min after exercise (HP60) ; 2) inspiring 12% O_2 from 10 min before exercise to 10 min after exercise (HP10) ; and 3) Inhaling air (MAX). Arterialized blood was drawn from a superficial arm vein. Arterial O_2 saturation (SaO_2), blood gas, plasma lactate, and plasma ammonia were determined. SaO_2 before exercise was lower in HP60 than that in HP10 (P<0.001). Blood Ph before exercise was lower in HP60 than that in MAX (P<0.05). Maximum plasma lactate concentrations were the same levels in all three tests. Maximum plasma ammonia concentration in HP60 was lower than that in MAX (P<0.01), while that in HP10 did not differ from that in MAX. From these results we suggest that a longer duration of hypoxic exposure before exercise may have resulted in a lower SaO_2 and a stronger respiratory alkalosis, maximum ammonia concentration which has lead a lower at maximal exercise in hypoxia.
2004-11-20