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

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

Evaluation of hyperpolarization potentials and nerve conduction parameters in axonal neuropathic patients

Neuropathies are diagnosed on the basis of some specific parameters of compound motor unit action potential [CMAP]. The slowing of conduction velocity along with relatively, preserved amplitude considered an indication of demyelination. While, amplitude reduction and slightly slowed conduction velocity, referred to axonal degeneration. Further, CMAP shape and distal latencies are also important for the diagnosis of neuropathies. Although, hyperpolarization is one of the important phase of CMAP but, it is mentioned only in the cases of nerve conduction block and never considered to identify other neuropathies. Therefore, in the present study the hyperpolarization phase of CMAP has been compared and evaluated in terms of its amplitude and duration and its occurrence in axonal neuropathy. The CMAP records of normal subjects and axonal neuropathic patients; randomly selected from OPD cases and evaluated for the occurrence of hyperpolarization, its amplitude, duration, latencies, CMAP amplitude and NCV. The recordings were obtained from the stimulation of median and tibial nerves [both distally and proximally] with recordings of CMAP from Abductor Pollicis Brevis and Abductor Hallucis muscles, respectively. The amplitude and duration of hyperpolarization and other parameters measured from both, median and tibial nerves were significantly lesser in neuropathic patients than the normal ones. Hyperpolarization reduces significantly in axonal neuropathy and this phase of CMAP may also be considered for the evaluation in other neuropathies. Further, criteria may be formulated for the diagnosis of various neuropathies using hyperpolarization phase of CMAP