Abstract
Basic mechanical and electrical properties of rat extensor muscle were analyzed 4--6 wk after thyroid removal. Isometric twitch tensions in thyroidectomized (Tx) rat muscle varied considerably, with over 60% of the muscles showing abnormally low values and the remainder showing a high twitch force. The duration of the twitch was significantly increased from 137 to 245 ms but contraction and half-relaxation times were not significantly changed. Tetanic force was not effected by thyroidectomy. Electrical properties of the muscle fiber membranes were made exclusively via intracellular techniques. The resting membrane potential was slightly higher in thyroidectomized rats (-79 mV) as compared to sham controls (-78 mV). Both direct and indirect action potentials showed higher overshoots, amplitudes, and rates of depolarization in thyroidectomized rats. The threshold of the indirect action potential appeared at a higher transmembrane potential as compared to sham-operated controls. The input resistance, space constant, time constant, and specific membrane resistance were all significantly increased in thyroidectomized rat extensor muscle, whereas fiber diameter and capacitance were significantly decreased. Estimates of specific ionic conductance show that both potassium and chloride conductance are decreased in thyroidectomized rat muscle.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
