Wave-like variations in muscular fatigue curves / by C.T. Symons.

  • Symons, C. T.
Date:
[1908?]
Catalogue details

Licence: Public Domain Mark

Credit: Wave-like variations in muscular fatigue curves / by C.T. Symons. Source: Wellcome Collection.

    12/20 page 394
    the usual rate of stimulation with pauses, the waves are again clearly shown, though perhaps in a somewhat less marked degree. Other muscles of the frog, besides the gastrocnemius, have also been used. The gracilis-semi-membranosus preparation gives the same result as the gastrocnemius. But no result has been obtained with sartorius or hyoglossus. The former merely gives an initial rise in the summit line after each pause. As the heart showed the treppe so clearly it was thought possible that a positive result might be obtained with this muscle. But no result was obtained with an isolated quiescent ventricle preparation from the frog. In most of the experiments summer frogs have been used, but the variations have also been obtained with muscles from winter frogs in March and November. The toad’s gastrocnemius has also been tried. In most cases no waves were obtained : but in some cases small slow variations appeared, somewhat similar to those obtained with the frog’s gastrocnemius under isometric conditions. These variations with toad’s muscle, when obtained, were influenced in the same way by temperature as those obtained with frog’s muscle. The toad’s sartorius did not give any evident signs of the variations. Certain mammalian muscles have been tried; guinea pigs and rats, under urethane or pithed, were used. But it was found somewhat difficult to get a smooth summit line. However, in one case, with a gastrocnemius muscle from a pithed rat, fatigued in the usual way, definite traces of waves were obtained. The best results were always obtained by using the gastrocnemius of the frog and the method of pauses. Hence these means have been used to investigate in greater detail the production of the waves in relation to temperature, rhythm, and various reagents. With constant temperature, tension and rate of stimulation, the time for one wave-length is approximately constant for each particular stage of the fatigue curve. There is a considerable tendency for the waves to become slower in the later stages of fatigue, especially when the muscle is under abnormal conditions such as an atmosphere of carbon dioxide. With increasing temperature the wave-time decreases, until at about 30° C. no waves can be evoked. The following figures are from some experiments in which the temperature variations were carefully measured, the initial wave after a pause being the only one reckoned in each case. From the figures given it will be seen that for any particular rate of stimulation the wave-time decreases as the temperature rises.
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