Effect of cast immobilization on contractile characteristics of skeletal muscles of uromastix

ABSTRACT

Cast immobilized [Imb] mammalian skeletal muscles exhibits reduced tension generation ability with morphometric changes and atrophy. However, controversies still exist with respect to changes in muscle mechanics in different positions of immobilization [IMB]. In addition, reptilian muscles have been ignored generally, and for the effects of IMB, specially. This study was carried out to observe the effects of different positions of IMB on contraction parameters of Uromastix skeletal muscles. Left hind limb was Imb in stretched knee and flexed ankle position for 20 days, right being the control [Cont]. After 20 days Sartorius [Sar], Gastrocnemius [Gas]. Peroneus Longus [PL] and Peroneus Brevis [PB] muscles were isolated to record the isometric twitch and tetani for the measurements of tension, rate of rise of tension [dp/dt] and duration of active state [DAS]. After IMB, morphometric parameter does not change significantly in any muscle except the stretched and flexed lengths in Gas. The tensions however, reduced significantly in Imb Sar and Gas which were non-significantly greater in the Imb PL and PB. The dp/dt parameters and DAS reduced in Imb Sar, Gas and PL. It was however, significantly higher in Imb PB. Skeletal muscle mechanics differ for different positions of IMB in reptilian muscle model as well. The earlier reported controversies probably indicate differences in IMB induced stretch, dimensions and anatomy of individual muscle of different animal models