Effects of epinephrine on glucose metabolism in contracting rat skeletal muscles. Jensen, Rune Aslesen & J_rgen. Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, P.O.Box 1105 Blindern, N-0317 Oslo, Norway, The Norwegian University of Sport and Physical Education, P.O.Box 4014, Ullev[angstrom]al, Hageby, N-0806 Oslo, Norway
APStracts 5:0111E, 1998.
The effects of epinephrine on glucose metabolism during contractile activity and insulin stimulation were investigated in fast twitch (epitrochlearis) and slow twitch (soleus) muscles from Wistar rats. All muscles were mounted on contraction apparatuses and some of them were stimulated electrically for 30 min in vitro. Glucose uptake and glucose phosphorylation were measured with 2-[1,2 3H(N)]-deoxy-D -glucose and glucose transport with 3-O-[methyl-3H]-methyl-D-glucose. [1-14C]-D-mannitol was used to correct for extracellular space. In epitrochlearis, both contraction and insulin increased glucose transport by 3 fold, and combined they showed an additive effect. Epinephrine (10-6 M) did not influence glucose transport across the membrane during contractile activity or insulin stimulation. In the absence of epinephrine, similar glucose phosphorylation was obtained during contraction and during insulin stimulation in epitrochlearis ( 12 mmol _ kg dw-1 _ 30 min-1). In the presence of epinephrine, 9.5 +/- 0.6 mmol _ kg dw-1 _ 30 min-1 glucose was phosphorylated during contraction whereas only 2.0 +/- 0.3 mmol _ kg dw-1 _ 30 min-1 was phosphorylated during insulin stimulation (p<0.01), despite a similar glucose 6-phosphate concentration. Comparable results were obtained in soleus. In conclusion, our data suggest that epinephrine inhibits glucose phosphorylation much less during contraction than during insulin stimulation. 

Received 25 November 1997; accepted in final form 13 May 1998.
APS Manuscript Number E552-7.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1998 The American Physiological Society.
Published in APStracts on 16 June 1998