P-type Ca2+ channels trigger stimulus-evoked [3H]acetylcholine release from mammalian motor endplates.
In the present experiments it was tested whether omega-agatoxin-IVA, a peptide blocking P-type voltage-dependent Ca2+ channels, inhibits the evoked release of newly synthesized [3H]acetylcholine from the rat phrenic nerve. Release of [3H]acetylcholine was evoked by electrical stimulation of the isolated phrenic nerve (100 or 750 pulses at 5 Hz). omega-Agatoxin-IVA inhibited evoked [3H]acetylcholine release in a concentration-related manner; inhibition started at a concentration of 30 nM with complete block occurring at 500 nM. In conclusion, the present experiments demonstrate that omega-agatoxin-IVA-sensitive P-type Ca2+ channels are critically involved in the regulation of stimulus-induced transmitter release at mammalian motor endplates.
Wessler
I
I
Department of Pharmacology, University of Mainz, Germany.
Dooley
D J
DJ
Lohr
B
B
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D002121:Calcium Channel Blockers / Q000008:administration & dosage / Q000494:pharmacology*; D015220:Calcium Channels / Q000502:physiology*; D004558:Electric Stimulation; D005260:Female; D007553:Isotope Labeling; D008297:Male; D009045:Motor Endplate / Q000187:drug effects / Q000378:metabolism*; D010791:Phrenic Nerve / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013111:Spider Venoms / Q000008:administration & dosage / Q000494:pharmacology*; D009435:Synaptic Transmission / Q000187:drug effects; D014316:Tritium / Q000378:metabolism; D020867:omega-Agatoxin IVA
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D013111:Spider Venoms; D020867:omega-Agatoxin IVA; D014316:Tritium; D000109:Acetylcholine