Five male subjects performed steady exercise on a cycle ergometer at an intensity of 60% maximal 0
2 uptake (V0
2max) for 6 min on three separate occasions while breathing gas mixtures of 12, 16 or 21% 0
2 in N
2 Expired gas fractions, ventilation, heart rate, arterial 0
2 saturation (Sa0
2), blood lactate (La) and plasma catecholamines (epinephrine: E and norepinephrine: NE) were measured. 0
2 uptake (V0
2) was calculated for the last minute of exercise. Blood samples were drawn at rest and immediately after exercise. By inspiring hypoxic gas mixtures, the Sa0
2 value decreased during exercise to 85.0±5.4 (16%) and 66.4±4.1 (12%) from 95.0±0. 1 in normoxia. V0
2 during exercise was not different among the three conditions. Exercise-induced La accumulation was increased by hypoxia. E and NE during exercise were not affected by hypoxia statistically. There was a significant correlation between La and E (P<0.01) and between La and NE (P<0.01) during exercise in the three conditions. The present findings suggest a relationship between glycogen metabolism and sympathoadrenal activity which results in an increase of plasma catecholamines during exercise in humans acutely exposed to hypoxia.
抄録全体を表示