[Mechanical responses on isolated frog neuromuscular preparations in the presence of calcitonin].
Previous observations had shown that, in the isolated rat preparations, calcitonin facilitates the excitement transmission from autonomic nerve-endings to smooth muscle. The present research, was designed to verify whether this facilitation effect could be present in somatic nerve-endings too. For this reason, we used the isolated frog "sciatic nerve-gastrocnemius muscle" preparation where the calcitonin influence on the beginning of a complete tetanic response was studied. The motor nerve-endings were stimulated at different frequencies. It was observed that the added calcitonin and/or an increased [Ca++] medium induced a complete tetanic response also at stimulating frequencies that, in the controls, provoked only a clonic response. Moreover, both the calcitonin and the increased [Ca++] medium frequently induced an increase in the mechanical muscle tension developed. These facilitating effects were reduced or even abolished with inhibition of Ca++-passage through the cell membrane by nifedipine. Therefore, we could hypothesize that the added calcitonin causes increased Ach-release from the somatic nerve-endings and that this action depends on facilitated Ca++-passage through the cell membrane of the nerve-endings and of the muscle fibres too.
D000818:Animals; D001001:Anura; D002116:Calcitonin / Q000494:pharmacology*; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D009469:Neuromuscular Junction / Q000187:drug effects*
D002116:Calcitonin
Risposte meccaniche di preparati neuromuscolari isolati di rana in presenza di calcitonina.