Insulin and Glucagon Immunoreactivity During High-Intensity Exercise Under Opiate Blockade
Human Performance and Recreation
Eight fit men [maximum oxygen consumption (VO2max) 64.6 (1.4) 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% VO2max). 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 mi) and the other after receiving a placebo (P; 0.9% NaCl saline; 3 mi). 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) is 43.8 (5) pmol l(-1)]. These data suggest that endogenous opioids may augment the glucagon response during intense exercise.
European Journal of Applied Physiology and Occupational Physiology
Angelopoulos, T. J.,
Robertson, R. J.,
(1997). Insulin and Glucagon Immunoreactivity During High-Intensity Exercise Under Opiate Blockade. European Journal of Applied Physiology and Occupational Physiology, 75(2), 132-135.
Available at: http://aquila.usm.edu/fac_pubs/5212