Abstract
Eight fit men [maximum oxygen consumption (O2max) 64.6 (1.9) ml · kg−1 · min−1, aged 28.3 (1.7) years (SE in parentheses) were studied during two treadmill exercise trials to determine the effect of endogenous opioids on insulin and glucagon immunoreactivity during intense exercise (80% O2max). A double-blind experimental design was used with subjects undertaking the two exercise trials in counterbalanced order. Exercise trials were 20 min in duration and were conducted 7 days apart. One exercise trial was undertaken following administration of naloxone (N; 1.2 mg; 3 ml) and the other after receiving a placebo (P; 0.9% NaCl saline; 3 ml). Prior to each experimental trial a flexible catheter was placed into an antecubital vein and baseline blood samples were collected. Immediately after, each subject received either a N or P bolus injection. Blood samples were also collected after 20 min of continuous exercise (running). Glucagon was higher (P < 0.05), while insulin was lower (P < 0.05), during exercise compared with pre-exercise values in both trials. However, glucagon was higher (P < 0.05) in the P than in the N exercise trial [141.4 (8.3) ng · l−1 vs 127.2 (7.6) ng · l−1]. There were no differences in insulin during exercise between the P and N trials [50.2 (4.3) pmol · l−1 vs 43.8 (5) pmol · l−1]. These data suggest that endogenous opioids may augment the glucagon response during intense exercise.
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Accepted: 15 June 1996
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Angelopoulos, T., Robertson, R., Goss, F. et al. Insulin and glucagon immunoreactivity during high-intensity exercise under opiate blockade. Eur J Appl Physiol 75, 132–135 (1997). https://doi.org/10.1007/s004210050137
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DOI: https://doi.org/10.1007/s004210050137