Effects of intensity of acute-resistance exercise on rates of protein synthesis in moderately diabetic rats.
These studies determined whether increases in rates of protein synthesis observed in skeletal muscle after moderate or severe acute-resistance exercise were blunted by insulinopenia. Rats (n = 6-9 per group) were made insulin deficient by partial pancreatectomy or remained nondiabetic. Groups either remained sedentary or performed acute-resistance exercise 16 h before rates of protein synthesis were measured in vivo. Exercise required 50 repetitions of standing on the hindlimbs with either 0.6 g backpack wt/g body wt (moderate exercise) or 1.0 g backpack wt/g body wt (severe exercise). Insulin-deficient rats had a mean blood glucose concentration >15 mM and reduced insulin concentrations in the plasma. Rates of protein synthesis in gastrocnemius muscle were not different in all sedentary groups. The moderate-exercised nondiabetic group (192 +/- 12 nmol phenylalanine incorporated. g muscle-1. h-1) and moderate-exercised diabetic group (215 +/- 18) had significantly (P < 0.05, ANOVA) higher rates of protein synthesis than did respective sedentary groups. In contrast, diabetic rats that performed severe-resistance exercise had rates of protein synthesis (176 +/- 12) that were not different (P > 0.05) from diabetic sedentary rats (170 +/- 9), whereas nondiabetic rats that performed severe exercise had higher (212 +/- 24) rates compared with nondiabetic sedentary rats (178 +/- 10) P < 0.05. The present data in combination with previous studies [J. D. Fluckey, T. C. Vary, L. S. Jefferson, and P. A. Farrell. Am. J. Physiol. 270 (Endocrinol. Metab. 33): E313-E319, 1996] show that the amount of insulin required for an in vivo permissive effect of insulin on rates of protein synthesis can be quite low after moderate-intensity resistance exercise. However, severe exercise in combination with low insulin concentrations can ablate an anabolic response.
Farrell
P A
PA
Noll Physiological Research Center and Department of Kinesiology, University Park 16802, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033, USA.
Fedele
M J
MJ
Vary
T C
TC
Kimball
S R
SR
Jefferson
L S
LS
D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000378:metabolism* / Q000503:physiopathology; D007328:Insulin / Q000097:blood; D007700:Kinetics; D008297:Male; D009124:Muscle Proteins / Q000096:biosynthesis*; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000503:physiopathology; D010180:Pancreatectomy; D005082:Physical Exertion / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D007328:Insulin; D009124:Muscle Proteins