Anti-curare action of stannous ion in the frog neuromuscular junction.
For the purpose of elucidating the mechanism of action of stannous ion (Sn2+), we investigated effects of stannous chloride (SnCl2) on the twitch and on the electrical phenomena in the muscle fiber. Sciatic nerve-sartorius muscle preparations from the bullfrog were used as the material. Effect of SnCl2 was examined on the twitch partially inhibited by pretreatment with d-tubocurarine. SnCl2 (1-100 microM) antagonized d-tubocurarine and enhanced the twitch dose-dependently. Tartaric acid, which is the solvent used for SnCl2 solution, had no augmentative effect on the twitch, even at a concentration as high as 250 microM. SnCl2 (1-50 microM) increased the amplitude of the endplate potential; that is, it exerted an anti-curare action. The resting potential and the membrane resistance of the muscle fiber were not altered by 30 microM SnCl2. These findings lead to the conclusion that Sn2+ enhances the twitch by increasing the endplate potential of the muscle fibers.
Hattori
T
T
Department of Dental Pharmacology, Matsumoto Dental College, Shiojiri, Japan.
Maehashi
H
H
D000818:Animals; D003472:Curare / Q000037:antagonists & inhibitors*; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects; D009469:Neuromuscular Junction / Q000187:drug effects*; D010084:Oxidation-Reduction; D011892:Rana catesbeiana; D009435:Synaptic Transmission / Q000187:drug effects*; D014001:Tin / Q000494:pharmacology*
D014001:Tin; D003472:Curare