Physical exercise and normobaric hypoxia: independent modulators of peripheral cholecystokinin metabolism in man
Journal of applied physiology
Physical exercise and normobaric hypoxia: independent modulators of peripheral cholecystokinin metabolism in man. J Appl Physiol 90:  2001.-The purpose of the present investigation was to determine the independent effects of hypoxia and physical exercise on peripheral cholecystokinin (CCK) metabolism in humans. Thirty-two physically active men were randomly assigned in a double-blind manner to either a normoxic (N; n ϭ 14) or hypoxic (H; n ϭ 18)
... . During the acute study, subjects in the H group only participated in two tests, separated by 48 h, which involved a cycling test to exhaustion in normobaric normoxia and normobaric hypoxia (inspired O 2 fraction ϭ 0.21 and 0.16, respectively). In the intermittent study, N and H groups cycle-trained for 4 wk at the same relative exercise intensity in both normoxia and hypoxia. Acute normoxic exercise consistently raised plasma CCK during both studies by 290-723%, which correlated with increases in the plasma ratio of free tryptophan to branched chain amino acids (r ϭ 0.58-0.71, P Ͻ 0.05). In contrast, acute hypoxic exercise decreased CCK by 7.0 Ϯ 5.5 pmol/l, which correlated with the decrease in arterial oxygen saturation (r ϭ 0.56, P Ͻ 0.05). In the intermittent study, plasma CCK response at rest and after normoxic exercise was not altered after physical training, despite a slight decrease in adiposity. We conclude that peripheral CCK metabolism 1) is more sensitive to acute changes than chronic changes in energy expenditure and 2) is potentially associated with acute changes in tissue PO 2 and metabolic precursors of cerebral serotoninergic activity. 5-hydroxytryptamine; satiety; caloric intake; adipose tissue; aerobic capacity ENVIRONMENTAL HYPOXIA EXERTS potent anorectic effects and thus contributes to the hypophagia and cachexia frequently experienced during prolonged exposure to high altitude (2). Changes in long-and short-term signaling molecules that regulate food intake and energy homeostasis suggest a metabolic basis for these phenomena. Serum leptin has previously been shown Main effect for time ⌺ skinfolds, mm 30.1 Ϯ 7.3 26.0 Ϯ 5.3 30.9 Ϯ 7.3 26.7 Ϯ 5.4 Main effect for time Fat mass, kg 9.6 Ϯ 2.8 8.2 Ϯ 2.4 9.9 Ϯ 2.6 8.7 Ϯ 2.1 Main effect for time Fat-free mass, kg 65.0 Ϯ 4.2 64.9 Ϯ 4.5 65.3 Ϯ 6.9 66.7 Ϯ 7.4 Waist-to-hip, ratio 0.84 Ϯ 0.03 0.79 Ϯ 0.04 0.83 Ϯ 0.04 0.81 Ϯ 0.03 Values are means Ϯ SD. 108 PLASMA CHOLECYSTOKININ RESPONSE TO HYPOXIC EXERCISE by 10.220.33.