Summary
Mechanically skinned fibre preparations from the extensor digitorum longus muscle of the rat were used to test whether a rise in myoplasmic [NH4 +] in the range 2–10 mm interferes with the mechanism of excitation-contraction coupling in fast-twitch mammalian muscle. Under our conditions (pH 7.10, Mg2+ 1 mm, temperature 23° C), [NH4 +] up to 10 mm had little effect on the Ca+-activated force and on the peak of the t-system depolarization-induced force response. However, the duration of the depolarization-induced force response was decreased significantly at [NH4 +] ≥2 mm. From these data we conclude that the intracellular accumulation of NH4 + is not likely to play a major role in fatigue. Nevertheless, the build up of NH4 + during fatigue, may have a significant inhibitory effect on the force output by decreasing the duration of the t-system depolarization-induced activation of the contractile apparatus.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
AICKINC. C. & THOMASR. C. (1977) Microelectrode measurement of the intracellular pH and buffering power of mouse soleus muscle fibres. J. Physiol. 267, 791–810.
BAYLORS. M., CHANDLERW. K. & MARSHALLM. W. (1983) Sarcoplasmic reticulum calcium release in frog skeletal muscle fibres estimated from arsenazo III calcium transients. J. Physiol. 344, 625–66.
CAMPBELLJ. W. (1973) Nitrogen excretion. In Comparative Animal Physiology (edited by LADD PROSSERC.) pp. 279–316. Philadelphia: W. B. Saunders Co.
FITTSR. H. (1994) Cellular mechanisms of muscle fatigue. Physiol. Rev. 74 (1), 49–94.
HEALDD. E. (1975) Influence of ammonium ions on mechanical and electrophysiological responses of skeletal muscle. Am. J. Physiol. 229 (5), 1174–9.
HILLEB. (1993) Ionic Channels of Excitable Membranes Ch. 13, pp. 337–61. Sunderland, MA: Sinauer Associates.
LAMBG. D. & STEPHENSOND. G. (1990) Calcium release in skinned muscle fibres of the toad by transverse tubule depolarization or by direct stimulation. J. Physiol. 423, 495–517.
LAMBG. D. & STEPHENSOND. G. (1994) Effects of intracellular pH and [Mg2+] on excitation-contraction coupling in skeletal muscle fibres of the rat. J. Physiol. 478(2), 331–9.
LOWENSTEINJ. M. (1972) Ammonia productin in muscle and other tissues: the purine nucleotide cycle. Physiol. Rev. 52, 382–414.
MEYERR. A. & TERJUNGR. L. (1979) Differences in ammonia and adenylate metabolism in contracting fast and slow muscle. Am. J. Physiol. 6(2), C111–18.
MUTCHB. J. C. & BANISTERE. W. (1983) Ammonia metabolism in exercise and fatigue: a review. Med. Sci. Sports Exercise 15(1), 41–50.
REESB. B. & STEPHENSOND. G. (1987) Thermal dependence of maximum Ca2+-activated force in skinned muscle fibres of the toad Bufo marinus acclimatised at different temperatures. J. Exp. Biol. 129, 309–27.
STEPHENSON, D. G. & LAMB, G. D. (1993) Visualization of the transverse tubular system in isolated intact and in mechanically skinned muscle fibres of the cane toad by confocal laser scanning microscopy. J. Physiol. 459, 15P.
STEPHENSONG. M. M. & STEPHENSOND. G. (1993) Endogenous MLC2 phosphorylation and Ca2+-activated force in mechanically skinned skeletal muscle fibres of the rat. Pflügers Arch. 424, 30–8.
STEPHENSON, G. M. M. & STEPHENSON, D. G. (1995) Rapid effects of D-glucose-6-phosphate and ammonia on contractile properties of single muscle fibres of the rat. Proc. Austral. Physiol. Pharmacol. Soc. 26, 127P.
STEPHENSON, G. M. M. & STEPHENSON, D. G. (1996) Effect of ammonia on contractile properties of mechanically skinned single muscle fibres from the rat. Muscle-Nerve Suppl. 4, S43.
STEPHENSOND. G. & WILLIAMSD. A. (1981) Calciumactivated force responses in fast-and slow-twitch skinned muscle fibres of the rat at different temperatures. J. Physiol. 317, 281–302.
STEPHENSONG. M. M., O'CALLAGHANA. & STEPHENSOND. G. (1994) A single study of contractile and biochemical properties of skeletal muscles in streptozotocin-induced diabetic rats. Diabetes 43, 622–8.
TASHIROS. (1922) Ammonia production in the nerve fibre during excitation. Am. J. Physiol. 60, 519–43.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Stephenson, G.M.M., Stephenson, D.G. Effects of ammonium ions on the depolarization-induced and direct activation of the contractile apparatus in mechanically skinned fast-twitch skeletal muscle fibres of the rat. J Muscle Res Cell Motil 17, 611–616 (1996). https://doi.org/10.1007/BF00154055
Received:
Revised:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00154055