Participation of calcium ions in stannous chloride-induced facilitation of transmitter release from frog motor nerve terminals.
To determine whether Ca2+ participates in the augmentative action of SnCl2 on the transmitter release, we have investigated interactions between SnCl2 and Cd2+, verapamil, or low Ca2+ on endplate potentials (e.p.p.) and have compared the effect of SnCl2 with that of Mg2+ on miniature endplate potentials (m.e.p.p.). SnCl2 increased the e.p.p. amplitude dose-dependently. Cd2+, verapamil and low Ca2+ shifted the dose-response relationship between SnCl2 and the e.p.p. downwards. In contrast to Mg2+, SnCl2 increased the m.e.p.p. frequency with raised K+ concentration in the medium. These results suggest that Ca2+ participates in the SnCl2-induced facilitation of the transmitter release and that SnCl2 enhances the Ca2+ entry into the nerve terminals.
Hattori
T
T
Department of Dental Pharmacology, Matsumoto Dental College, Shiojiri, Japan.
Maehashi
H
H
D000818:Animals; D002104:Cadmium / Q000494:pharmacology; D002118:Calcium / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008564:Membrane Potentials / Q000187:drug effects; D009045:Motor Endplate / Q000187:drug effects / Q000378:metabolism*; D009469:Neuromuscular Junction / Q000378:metabolism*; D018377:Neurotransmitter Agents / Q000378:metabolism*; D011892:Rana catesbeiana; D014001:Tin / Q000494:pharmacology*; D017971:Tin Compounds; D014700:Verapamil / Q000494:pharmacology
D018377:Neurotransmitter Agents; D017971:Tin Compounds; D002104:Cadmium; C023599:stannous chloride; D014001:Tin; D014700:Verapamil; D002118:Calcium