The transformation of myosin in cross‐innervated rat muscles

Abstract

SUMMARY1. The characteristics of isometric twitch and tetanic contractions have been determined for normal (N-EDL, N-SOL), self-innervated (S-EDL, S-SOL) and cross-innervated (X-EDL, X-SOL) extensor digitorum longus (EDL) and soleus (SOL) muscles of the rat at 350 C. The muscles were then used for biochemical analyses of properties of myosin and actomyosin.2. The ATPase activities of myosin and actomyosin of X-EDL decreased to the level of those of N-SOL or S-SOL, and the ATPase activities of X-SOL approached those of N-EDL or S-EDL. Of the various ATPase activities, the actin-and Mg2+-activated ATPase activity of myosin and the Mg2+-activated ATPase activity of actomyosin showed the highest degree of correlation with the intrinsic speed of shortening of the muscles.3. Myosin of normal, self-innervated, and cross-innervated muscles combined with F-actin superprecipitated at rates which were proportional to the speed of muscle contraction.4. The pH profile curve and the ATP-induced dinitrophenylation reaction revealed that the structure of myosin of X-EDL was altered to that of N-SOL or S-SOL, and the structure of myosin of X-SOL was modified to that of N-EDL or S-EDL.5. No differences were found in the yield of myosin of normal, selfinnervated, and cross-innervated extensor digitorum longus and soleus muscles.

Relationship between the characteristics of rigor‐mortis‐related actomyosin and muscle fiber types in the ordinary muscle of various fishes

“…Ebashi and Ebashi succeeded in quantitating the superprecipitation reaction by measuring the turbidity, reporting that an increase in turbidity surely corresponds to contraction and that a decrease in turbidity corresponds to relaxation . In addition, changes in the speed of superprecipitation of myosin are consistent with changes in the intrinsic speed of the muscles . Furthermore, the superprecipitation values correlate with Mg 2+ ‐ATPase activity in low ionic strength solutions, whereas superprecipitation rates depend neither on ATPase activity values nor on superprecipitaton values .…”

“…3,4 In addition, changes in the speed of superprecipitation of myosin are consistent with changes in the intrinsic speed of the muscles. 5 Furthermore, the superprecipitation values correlate with Mg 2+ -ATPase activity in low ionic strength solutions, whereas superprecipitation rates depend neither on ATPase activity values nor on superprecipitaton values. 6 As mentioned earlier, differences in the organization of actomyosin might affect the relationship between the level of superprecipitation reaction and Mg 2+ -ATPase activity.…”

Muscle Changes in Aging

“…3 It is possible that regeneration of previously damaged muscle fibers fails, but this seems unlikely. 1 A more reasonable explanation would be a reorganization of the aging motor unit pool.…”

An Assimilation of TRIZ in Dissecting the Statistical Outcomes of Tactile Sensitivity, Pinch Force and Endurance among Elderly People

“…Therefore, it is vital that elderlies continue to remain active to continually drive muscles. The importance of keeping the fingers active with different types of movements is further emphasised in a study on midlife female dentist whereby dentist with low variation in work task history are at a higher risk of low pinch grip strength ( According to researchers, the increase of type I fibres could be due to motor nerves having trophic influence on muscle fibres (Bárány & Close, 1971). The most probable explanation to this occurrence would be the reorganisation of aging motor units.…”