Abstract
It has been reported that the peak of the staircase or the enhanced tension response during low frequency stimulation is delayed in fatigued fast muscle. Our purpose was to determine if the rate and extent of regulatory myosin light chain (P-LC) phosphorylation, a molecular mechanism associated with the positive staircase, are also altered by fatigue. The staircase contractile response, muscle metabolites and phosphate incorporation by the P-LC were assessed at 0, 5, 10 or 20 s of 10-Hz stimulation, in either non-fatigued (control) or fatigued (10 Hz for 5 min, followed by 20 min of recovery) rat gastrocnemius muscle in situ. The concentration of adenosine triphosphate (ATP) in fatigued muscles, 21 ±0.9 mmol · kg−1 (dry weight) was significantly lower (P<0.05) than in the control muscles, 26.1±1.5 mmol · kg−1. In both groups, ATP content was significantly lower after 20 s of 10 Hz stimulation. The P-LC phosphate content (in mol phosphate · mol−1 P-LC) was 0.10, 0.38, 0.60 and 0.72 after 0, 5, 10 or 20 s of 10 Hz stimulation in control muscles, but only 0.03, 0.08, 0.11 and 0.19 at these times in fatigued muscles. Although the absolute magnitude of tension potentiation was attenuated in proportion to the depressed twitch amplitude, these surprisingly low levels of phosphorylation were associated with 0, 48, 79 and 86% potentiation of the developed tension at these times in contrast with 0, 71, 87 and 49% potentiation in control muscles. These data demonstrate that while the rate and extent of phosphate incorporation is depressed in fatigued muscle, tension potentiation is still evident. The persistence of potentiation in the fatigued state indicates that either this condition results in greater potentiation for a given level of P-LC phosphorylation, or that factors in addition to P-LC phosphorylation are responsible for the staircase response.
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References
Allen DG, Lee JA, Westerblad H (1989) Intracellular calcium and tension during fatigue in isolated single muscle fibres from Xenopus laevis. J Physiol (Lond) 415: 433–458
Amorena CE, Wilding TJ, Manchester JK, Ross A (1991) Changes in intracellular pH caused by high K in normal and acidified frog muscle. J Gen Physiol 96: 959–972
Ariano MA, Armstrong RB, Edgerton VR (1973) Hindlimb muscle fiber populations of five mammals. J Histochem Cytochem 21: 51–55
Blinks JR, Rudel R, Taylor SR (1978) Calcium transients in isolated amphibian skeletal muscle fibres: detection with aequorin. J Physiol (Lond) 277: 291–323
Blumenthal DK, Stull JT (1980) Activation of skeletal muscle myosin light chain kinase by Ca2+ and calmodulin. Biochemistry 19: 5608–5614
Close R, Hoh JFY (1968) The after-effects of repetitive stimulation on the isometric twitch contraction of rat fast skeletal muscle. J Physiol (Lond) 197: 461–477
Close R, Hoh JFY (1968) The influence of temperature on isometric contractions of rat skeletal muscles. Nature 217: 1179–1180
Cooke R, Franks K, Luciani GB, Pate E (1988) The inhibition of rabbit skeletal muscle contraction by hydrogen ions and phosphate. J Physiol (Lond) 395: 77–97
Desmedt JE, Hainaut K (1977) Inhibition of the intracellular release of calcium by dantrolene in barnacle giant muscle fibres. J Physiol (Lond) 265: 565–585
Fabiato A, Fabiato F (1978) Effects of pH on the myofilaments and the sarcoplasmic reticulum of skinned cells from cardiac and skeletal muscles. J Physiol (Lond) 276: 233–255
Gillis JM, Thomason D, Lefevre J, Kretsinger RH (1982) Parvalbumins and muscle relaxation: a computer simulation study. J Muscle Res Cell Motil 3: 377–398
Houston ME, Green HJ, Stull JT (1985) Myosin light chain phosphorylation and isometric twitch potentiation in intact human muscle. Pflügers Arch 403: 348–352
Houston ME, Lingley MD, Stuart DS, Grange RW (1987) Myosin light chain phosphorylation in intact human muscle. FEBS Lett 219: 469–471
Keppel G (1973) Design and analysis: a researcher's handbook. Prentice Hall, Englewoods Cliffs, New Jersey
Krarup C (1981) Enhancement and diminution of mechanical tension evoked by staircase and by tetanus in rat muscle. J Physiol (Lond) 311: 355–372
Leslie GC, Part NJ (1981) The action of dantrolene sodium on rat fast and slow muscle in vivo. Br J Pharmacol 72: 655–672
Lopez JR, Wanek LA, Taylor SR (1981) Skeletal muscle: length-dependent effects of potentiating agents. Science 214: 79–82
Lowry OH, Passoneau SV (1971) A flexible system of enzymatic analysis. Academic Press, New York, pp 146–218
MacIntosh BR (1991) Skeletal muscle staircase response with fatigue or dantrolene sodium. Med Sci Sports Exerc 23: 56–63
MacIntosh BR, Gardiner PF (1987) Posttetanic potentiation and skeletal muscle fatigue: interactions with caffeine. Can J Physiol Pharmacol 65: 260–268
MacIntosh BR, Kupsh CC (1987) Staircase, fatigue and caffeine in skeletal-muscle in situ. Muscle & Nerve 10: 717–722
Moore RL, Stull JT (1984) Myosin light chain phosphorylation in fast and slow skeletal muscles in situ. Am J Physiol 247: C462-C471
Moore RL, Houston ME, Iwamoto GA, Stull JT (1985) Phosphorylation of rabbit skeletal muscle myosin in situ. J Cell Physiol 125: 301–305
Moore RL, Palmer BM, Williams SL, Tanabe H, Grange RW, Houston ME (1990) Effect of temperature on myosin phosphorylation in mouse skeletal muscle. Am J Physiol 259: C432-C438
Palmer BM, Moore RL (1989) Myosin light chain phosphorylation and tension potentiation in mouse skeletal muscle. Am J Physiol 257: C1012-C1019
Persechini A, Stall JT, Cooke R (1985) The effect of myosin phosphorylation on the contractile properties of skinned rabbit skeletal muscle fibers. J Biol Chem 260: 7951–7954
Silver PJ, Stull JT (1982) Quantification of myosin light chain phosphorylation in small tissue samples. J Biol Chem 257: 6137–6144
Stuart DS, Lingley MD, Grange RW, Houston ME (1987) Myosin light chain phosphorylation and contractile performance of human skeletal muscle. Can J Physiol Pharmacol 66: 49–54
Stull JT, Nunnally MH, Moore RL, Blumenthal DK (1985) Myosin light chain kinases and myosin phosphorylation in skeletal muscle. Adv Enzyme Regul 23: 123–140
Sweeney HL, Stull JT (1986) Phosphorylation of myosin in permeabilized mammalian cardiac and skeletal muscle cells. Am J Physiol 250: C657-C660
Westerblad H, Lannergren J (1990) Decreased Ca2+ buffering contributes to slowing of relaxation in fatigued Xenopus muscles fibres. Acta Physiol Scand 139: 243–244
Westerblad H, Lee JA, Lamb AG, Bolsover SR, Allen DG (1990) Spatial gradients of intracellular calcium in skeletal muscle during fatigue. Pflügers Arch 415: 734–740
Williams JH (1990) Effects of low calcium and calcium antagonists on skeletal muscle staircase and fatigue. Muscle & Nerve 13: 1118–1124
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MacIntosh, B.R., Grange, R.W., Cory, C.R. et al. Myosin light chain phosphorylation during staircase in fatigued skeletal muscle. Pflugers Arch. 425, 9–15 (1993). https://doi.org/10.1007/BF00374497
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DOI: https://doi.org/10.1007/BF00374497