Cerebral ammonia uptake and accumulation during prolonged exercise in humans.

摘要: We evaluated whether peripheral ammonia production during prolonged exercise enhances the uptake and subsequent accumulation of within brain. Two studies determined cerebral (arterial jugular venous blood sampling combined with Kety-Schmidt-determined flow; n = 5) concentration in cerebrospinal fluid (CSF; 8) at rest immediately following either or without glucose supplementation. There was a net balance across brain 30 min exercise, whereas 3 h elicited an 3.7 +/- 1.3 micromol min(-1) (mean +/-s.e.m.) placebo trial 2.5 1.0 (P < 0.05 compared to rest, not different trials). At CSF below detection limit 2 microm all subjects, but it increased 5.3 1.1 glucose, further 16.1 3.3 after 0.05). Correlations were established between both (r2 0.87; P 0.05) 0.72; arterial level and, addition, weaker correlation 0.37; perceived exertion end exercise. The results let us suggest that may provoke fatigue, e.g. by affecting neurotransmitter metabolism.