. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. RECOVERY CONTRACTURE IN MUSCLE 405 Seeking for an explanation of this peculiar phenomenon it seemed rather probable that the presence or absence of the contracture might be due to differences in ion concentrations at the surface layer of muscle, since the efficiency of ions to produce contractures and influence the "tonus" of muscles is known (Neuschlosz, Gellhorn). But experi- ments did not prove the correctness of this view. The recovery con- tracture occurs not only if the muscle is kept in Ringer's solution but
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. RECOVERY CONTRACTURE IN MUSCLE 405 Seeking for an explanation of this peculiar phenomenon it seemed rather probable that the presence or absence of the contracture might be due to differences in ion concentrations at the surface layer of muscle, since the efficiency of ions to produce contractures and influence the "tonus" of muscles is known (Neuschlosz, Gellhorn). But experi- ments did not prove the correctness of this view. The recovery con- tracture occurs not only if the muscle is kept in Ringer's solution but also if the composition of that solution is much altered. An increase in the K or Ca concentration to ten times its original value did not notice- ably influence the strength of the recovery contracture. The phen- omenon was also observed in isotonic NaCl, Na2SO4 and LiCl solu- tions. If the K or Ca content of the muscle were responsible for the phenomenon in question, changes in concentration of these ions should be effective. Therefore it was thought that one might have to do here with a general salt effect as was first observed by Loeb (for further references compare Gellhorn, 1926 and 1929, pp. 153-163). In this case the contracture should be diminished or should not occur at all if the muscle were placed in a non-electrolyte solution during the re- covery period. In fact, the experiments carried out with glucose, sucrose and urea either alone, in isotonic solution or replacing different. FIG. 9. fr-curves. (m. sartorius.) Muscle 1 in Ringer's, muscle 2 in 3 cc. Ringer's + 17 cc. isotonic urea during recovery period. parts of Ringer's solution, yielded the expected results. Figures 9 and 10 show a typical experiment on sartorius and biceps. In Fig. 9 the recovery contracture was much decreased if the muscle remained in a solution consisting of Ringer's + urea during the recovery period. In Fig. 10 it is shown that recovery contracture is suppressed completely if the muscle
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