Implications of rapid early oxygen consumption in exercising skeletal muscle.

摘要

Measured directly in vivo (Wiist et al. 2011), O2 consumption rate (Vo2) in dog leg muscle during the rest-exercise transition increases faster than predicted on a first-order ADP-feedback model ('model 1' in Wiist et al. 2011). This yields a higher-order relationship between oxidative ATP synthesis rate (V) and [ADP] ('model 3'), resembling that inferred from post-exercise PCr kinetics (Jeneson et al. 1996) and adduced as a possible explanation of what (given the low V in relation to the maximum rate Vmax) is an anomalously high [ADP] in resting human muscle (Kemp et al. 2007). However, the VO2-[ADP] data are rather better explained by assuming a component of parallel activation ('model 4'), approximately quantifiable as an increasing apparent Vmax from rest into exercise (Wiist et al. 2011). This suggests three experimental tests, and raises a so far unanswered physiological question.