Different effects of toosendanin on perineurially recorded Ca(2+) currents in mouse and frog motor nerve terminals.
By perineurial recording, the effects of toosendanin (TSN), a presynaptic blocker, on nerve terminal calcium currents (I(Ca)) were observed in innervated triangularis sterni of the mouse and cutaneous pectoris of the frog. It was found that TSN blocked the slow component of I(Ca) insensitive to nifedipine and omega-conotoxin-GVIA, and increasing the extracellular Ca(2+) concentration partially antagonized the inhibitory effect in mouse motor nerve terminals. However, in the frog, TSN increased the slow component of I(Ca) and this effect disappeared in the presence of nifedipine in perfusion solution. Based on previous data showing that the slow component of I(Ca) were mediated by different subtypes of calcium channels in mouse and frog motor nerve terminals, we presume that TSN could exercise different effects on various subtypes of calcium channels.
Ding
J
J
Key laboratory of Neurobiology, Institute of Physiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue-Yang Road, 200031, Shanghai, People's Republic of China.
Xu
T H
TH
Shi
Y L
YL
D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000502:physiology*; D004365:Drugs, Chinese Herbal / Q000494:pharmacology*; D004553:Electric Conductivity; D051379:Mice; D009411:Nerve Endings / Q000378:metabolism*; D009466:Neuromuscular Blocking Agents / Q000494:pharmacology*; D009469:Neuromuscular Junction / Q000378:metabolism*; D009543:Nifedipine / Q000494:pharmacology; D011898:Ranidae; D014315:Triterpenes
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D004365:Drugs, Chinese Herbal; D009466:Neuromuscular Blocking Agents; D009543:Nifedipine; C036454:toosendanin; D014315:Triterpenes