[Effect of hypodynamia on initial speed of lactate transport in skeletal muscle sarcolemmal vesicles in rats].
Skeletal muscle sarcolemmal vesicles from control (C) and hindlimb suspended (S) rats were used to investigate the effect of unweighting on the lactate transporter activity. Sarcolemmal preparations were not different between the two groups. The efficiency of 4 weeks of hindlimb suspension was confirmed by a 40% decrease of citrate synthetase activity and a shift towards faster myosin isoforms in soleus muscle. The time course of 1 mM lactate uptake showed that the equilibrium was reached faster in group C (20 s) than in group S (40 s). The initial rate of 1 mM of lactate uptake decreased significantly (p < 0.05) after 4 weeks of hindlimb suspension. The initial rate of 50 mM lactate uptake did not differ significantly between the two groups. We conclude that 4 weeks of unweighting decreases significantly the skeletal muscle sarcolemmal lactate transport activity in rats. This result suggests that the level of physical activity probably plays a role on lactate transport regulation in muscle.
Dubouchaud
H
H
Laboratoire de Physiologie des Interactions, Hôpital A. de Villeneuve, Montpellier.
Granier
P
P
Mercier
J
J
Prefaut
C
C
D000818:Animals; D002950:Citrate (si)-Synthase / Q000378:metabolism; D018476:Hypokinesia / Q000378:metabolism*; D007773:Lactates / Q000493:pharmacokinetics*; D008297:Male; D018482:Muscle, Skeletal / Q000166:cytology*; D009218:Myosins / Q000737:chemistry; D051381:Rats; D017208:Rats, Wistar; D012508:Sarcolemma / Q000378:metabolism*
D007773:Lactates; D002950:Citrate (si)-Synthase; D009218:Myosins