Chronic electrical stimulation increases mct1 and lactate uptake in red and white skeletal muscle. McCullagh, Karl J. A., Robert C. Poole, Andrew P. Halestrap, Keith F. Tipton, Moira O'brien, Arend Bonen. Departments of Anatomy and Biochemistry, Trinity College Dublin, Dublin 2, Ireland, Department of Biochemistry, University of Bristol, Bristol, U.K., Department of Kinesiology, University of Waterloo, Waterloo, Ontario, N2L 3G1.
APStracts 4:0084E, 1997.
We examined whether chronic stimulation of red and white rat muscles increased the concentrations of the monocarboxylate transporter MCT1. Red (RTA) and white tibialis anterior (WTA), and extensor digitorum longus (EDL) muscles were chronically stimulated via the peroneal nerve for 7-days. Stimulated and contralateral control muscles were examined for MCT1 content, L-lactate uptake, LDH isoforms, and muscle fibre composition. MCT1 was 1.5 times greater in stimulated RTA, 3 times greater in stimulated WTA, and 1.9 times greater in stimulated EDL, compared to respective control muscles (P<0.05). L-Lactate uptake increased in all stimulated muscles (P<0.05) and this was highly correlated with the increase in MCT1 (r= 0.96). The heart type LDH subunits also increased in all stimulated muscles (P<0.05). The H-LDH subunits correlated highly with MCT1 in the muscles (r=0.83). There was no change in muscle type LDH subunits (P>0.05). There were negligible alterations in muscle fibre composition in the stimulated muscles, suggesting that the increase in MCT1 was independent of changes in muscle fibre composition. These studies are the first to demonstrate that chronic muscle contraction increases MCT1 concentrations, in both red and white skeletal muscles. 

Received 24 September 1996; accepted in final form 12 March 1997.
APS Manuscript Number E481-6.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 15 April 1997