Annals of the New York Academy of SciencesVolume 228, Issue 1 p. 105-120 DYNAMIC PROPERTIES OF SLOW AND FAST MUSCLE AND THEIR TROPHIC REGULATION* D. M. Lewis, D. M. Lewis Department of Physiology University of Bristol Bristol, EnglandSearch for more papers by this authorC. J. C. Kean and, C. J. C. Kean and Department of Physiology University of Bristol Bristol, EnglandSearch for more papers by this authorJ. D. McGarrick, J. D. McGarrick Department of Physiology University of Bristol Bristol, EnglandSearch for more papers by this author D. M. Lewis, D. M. Lewis Department of Physiology University of Bristol Bristol, EnglandSearch for more papers by this authorC. J. C. Kean and, C. J. C. Kean and Department of Physiology University of Bristol Bristol, EnglandSearch for more papers by this authorJ. D. McGarrick, J. D. McGarrick Department of Physiology University of Bristol Bristol, EnglandSearch for more papers by this author First published: March 1974 https://doi.org/10.1111/j.1749-6632.1974.tb20505.xCitations: 20 * This work was supported by a grant from the Muscular Dystrophy Associations of America Inc. and by personal grants from The Medical Research Council to C. K. and J. M. The computer used in these experiments was provided by a grant to Professor Buller by Aid for the Crippled Child. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume228, Issue1Trophic Function of the NeuronMarch 1974Pages 105-120 RelatedInformation

1. Isometric and isotonic contractions were recorded from cat flexor digitorum longus (FDL) and soleus muscles denervated for 28-35 days and compared with the responses of contralateral control muscles.2. Isometric twitch time to peak was longer in the denervated muscles than in the controls. Tetanic tension was reduced whether expressed as absolute units, per gram or per unit area. Absolute twitch tensions were reduced less below the control values with a consequent increase of twitch-tetanus ratio. These results agree with earlier reports; but, in contrast, there was no reduction in the relative rate of rise of tension in the isometric tetanus of denervated compared with control FDL. The maximum rate of rise of tension in the twitch was only a little less than that in the fully fused tetanus in the denervated muscles.3. Whole muscle shortening velocity was reduced in the denervated soleus with no change in the number of sarcomeres per fibre. There was a smaller change in FDL muscles. This was the result of an increase in the number of sarcomeres per fibre which followed denervation in FDL, compensating for a decreased velocity of shortening of the sarcomere. Maximum sarcomere shortening velocity was reduced by 30% relative to control values in both muscles.4. Measurements were made of the isometric contractions resulting from pairs of stimuli in an attempt to assess the period of maximal activation in the twitch. Maximum summation occurred when the second stimulus was given close to the time of the peak of the twitch in the denervated muscles.