Effect of prior eccentric contractions on lactate/h+ transport in
rat skeletal muscle.
Pilegaard, Henriette, and Sven Asp.
Copenhagen Muscle Research Centre, August Krogh Institute,
University of Copenhagen, Denmark
APStracts 4:0277E, 1997.
The effect of prior eccentric contractions on skeletal muscle
lactate/H+ transport was investigated in rats. Lactate transport was
measured in sarcolemmal giant vesicles obtained from soleus, red (RG)
and white (WG) gastrocnemii muscles two days after intense eccentric
contractions (ECC) and from the corresponding contralateral control
(CON) muscles. The physio-chemical buffer capacity was determined in
the three muscle types from both ECC and CON legs. Furthermore, the
effect of prior eccentric contractions on release and muscle content
of lactate and H+ during and after supramaximal stimulation was
examined using the perfused rat hindlimb preparation. The lactate
transport rate was lower (P<0.05) in vesicles obtained from ECC-WG
(29%) and ECC-RG (13%) than in vesicles from the contralateral
control muscles. The physio-chemical buffer capacity was reduced
(P<0.05) in ECC-WG (13%) and ECC-RG (9%) compared with the
corresponding control muscles. There were only marginal effects on
the soleus muscle. Muscle lactate concentrations and release of
lactate during recovery from intense isometric contractions were
lower (P<0.05) in ECC than in CON hindlimbs indicating decreased
anaerobic glycogenolysis. In conclusion, the sarcolemmal lactate/H+
transport capacity as well as the physio-chemical buffer capacity
were reduced in prior eccentrically stimulated WG and RG in rats
suggesting that muscle pH regulation may be impaired after
unaccustomed eccentric exercise. In addition, the data indicate that
the glycogenolytic potential is decreased in muscles exposed to prior
eccentric contractions.
Received 13 June 1997; accepted in final form 10 December 1997.
APS Manuscript Number E279-7.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 7 January 1998