Modifications in the histochemical and biochemical changes in tenotomized rat soleus by denervation

Abstract

Response of tenotomized rat soleus muscle to denervation performed at different time intervals, has been investigated. Tenotomized muscles showed typical central core lesions seven days post-operatively. These were not observed in m-ATPase stained sections of simultaneously denervated and tenotomized muscles, and muscles denervated 24 h after tenotomy. Central core lesions were not prevented in muscles denervated 28 h after tenotomy, indicating that tenotomy effects responsible for central lesions are completed by this time. Myosin light chain pattern of muscles denervated 28 h after tenotomy, and tenotomized only were similar showing increased LC3/LC1 ratio. Simultaneously denervated and tenotomized muscle however showed all the three light chains relatively equal in quantity. The results suggest that elimination of neural activation within 28 h prevents myofibrillar loss and minimized other changes which occur due to tenotomy.

Preserving sarcomere number after tenotomy requires stretch and contraction

“…Central core morphology represents the depolymerization of thick (myosin) filaments and thin (actin) filaments 33–35. Core formation in tenotomized muscles has been shown to be contractile activity dependent (i.e., reduced by denervation and increased by electrical stimulation) 37, 41, 42. Our findings further enforce the concept that sarcomere remodeling involves contractile activity‐dependent processes, because contractile activity during stretch (but not stretch alone) retains sarcomeres.…”

Passive stretch inhibits central corelike lesion formation in the soleus muscles of hindlimb-suspended unloaded rats

“…The degeneration of myofibrils after tenotomy correlates with the hypershortened state of the sarcomeres (3). The formation of CCLs in tenotomy is inhibited by denervation, suggesting that contractile activity is essential for lesion generation (1,34). It is unclear how muscle shortening and contractile activity interact to generate CCLs.…”

Influence of fixed muscle length and contractile properties on atrophy and subsequent recovery in the rat soleus and plantaris muscles

“…Thus, the amount of intracellular calcium released from the sarcoplasmic reticulum might be larger in the HUP group than in the HU group because contractile activity of the soleus muscle by isometric contraction was greater than that by isotonic contraction (Hurst and Fitts, 2003). Removing the contractile activities by denervation inhibits the formation of a central core lesion (Talesara and Jasra, 1986), suggesting that the elevation of intracellular calcium by muscle contractile activities might be one reason for the formation of the central core lesion in the soleus muscle in the HUP group. However, it is difficult to decide whether the central core lesion is due to protective adaptation or degeneration from the present findings although electron microscopic observations show that aggregates of mitochondria predominantly occur at the intact peripheral zone of the central core lesion (Abou Salem et al, 2001).…”