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. 2005 Jan 15;562(Pt 2):521-6.
doi: 10.1113/jphysiol.2004.078014. Epub 2004 Nov 18.

Lactate and force production in skeletal muscle

Michael Kristensen  1 , Janni Albertsen, Maria Rentsch, Carsten Juel
Affiliations

Lactate and force production in skeletal muscle

Michael Kristensen et al. J Physiol. .

Abstract

Lactic acid accumulation is generally believed to be involved in muscle fatigue. However, one study reported that in rat soleus muscle (in vitro), with force depressed by high external K(+) concentrations a subsequent incubation with lactic acid restores force and thereby protects against fatigue. However, incubation with 20 mm lactic acid reduces the pH gradient across the sarcolemma, whereas the gradient is increased during muscle activity. Furthermore, unlike active muscle the Na(+)-K(+) pump is not activated. We therefore hypothesized that lactic acid does not protect against fatigue in active muscle. Three incubation solutions were used: 20 mM Na-lactate (which acidifies internal pH), 12 mM Na-lactate +8 mm lactic acid (which mimics the pH changes during muscle activity), and 20 mM lactic acid (which acidifies external pH more than internal pH). All three solutions improved force in K(+)-depressed rat soleus muscle. The pH regulation associated with lactate incubation accelerated the Na(+)-K(+) pump. To study whether the protective effect of lactate/lactic acid is a general mechanism, we stimulated muscles to fatigue with and without pre-incubation. None of the incubation solutions improved force development in repetitively stimulated muscle (Na-lactate had a negative effect). It is concluded that although lactate/lactic acid incubation regains force in K(+)-depressed resting muscle, a similar incubation has no or a negative effect on force development in active muscle. It is suggested that the difference between the two situations is that lactate/lactic acid removes the negative consequences of an unusual large depolarization in the K(+)-treated passive muscle, whereas the depolarization is less pronounced in active muscle.

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Figures

Figure 1
Figure 1. Effect of 20 mM lactic acid or 20 mM Na-lactate or HCl titration on tetanic force in muscle pre-incubated with 10 mM K+
○, effect of 20 mm lactic acid on force development in muscle pretreated with 10 mm K+ (n = 8). ▪, effect of 20 mm Na-lactate (n = 14). Δ muscles were pre-incubated with 10 mm K+ in Tris-buffer pH 7.4 and subsequently incubated with Tris-buffer pH 6.8 titrated with HCl (no lactate present) (n = 3). ♦, Effect of a mixture of 12 mm Na-lactate and 8 mm lactic acid (n = 4). Error bars show s.e.
Figure 2
Figure 2. The effect of pH regulation on potassium uptake in resting muscle
Control: potassium uptake in resting soleus muscle (n = 8). Ouabain: effect of 10−3m ouabain on potassium uptake (n = 4). Na-lactate: effect of 20 mm Na-lactate on potassium uptake (n = 8). Na-lac/l. acid: effect of 12 mm Na-lactate +8 mm lactic acid (n = 8). L. acid: effect of 20 mm lactic acid (n = 4). DIDS + AMIL: effect of 0.5 mm DIDS and 0.5 mm amiloride on potassium uptake in muscle incubated with 20 mm Na-lactate (n = 4). *Significantly different from control; # significantly different from each other. Error bars show s.e.
Figure 3
Figure 3. Effect of lactate and lactic acid incubation on force development during fatiguing stimulation
From each rat one soleus muscle was incubated with the test solution for 15 min, the other soleus muscle served as control. The values represent the mean force (± s.e.m.) read every 30 s for 5 min. •, controls. ▭, muscles incubated with the test solution. A, muscles were incubated with 20 mm Na-lactate. n = 16 for both series. *Control and Na-lactate values significantly different (P < 0.05); #, P = 0.059. B, muscles incubated with 12 mm Na-lactate + 8 mm lactic acid (n = 8). C, muscles incubated with 20 mm lactic acid (n = 9). *Control and values for lactic acid incubation significantly different, P < 0.05
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References

    1. Aickin CC, Thomas RC. Micro-electrode measurement of the intracellular pH and buffering power of mouse soleus muscle fibers. J Physiol. 1977;267:791–810. - PMC - PubMed
    1. Buchanan R, Nielsen OB, Clausen T. Excitation- and β2-agonist-induced activation of the Na+–K+ pump in rat soleus muscle. J Physiol. 2002;545:229–240. - PMC - PubMed
    1. Fitts RH. Cellular mechanisms of muscle fatigue. Physiol Rev. 1994;74:49–94. - PubMed
    1. Henning R, Lomo T. Firing patterns of motor units in normal rats. Nature. 1985;314:164–166. 10.1038/314164a0. - DOI - PubMed
    1. Juel C. Lactate-proton transport in skeletal muscle. Physiol Rev. 1997;77:321–358. - PubMed

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