The effects of TMB-8 on acetylcholine release from frog motor nerve: interactions with adenosine.
The putative intracellular calcium (Ca) antagonist TMB-8 was shown to reduce postjunctional sensitivity and quantal acetylcholine (ACh) release at low micromolar concentrations. At 10-fold higher concentrations, TMB-8 also blocked caffeine-induced Ca release (as monitored electrophysiologically by changes in ACh release) but did not impair the ability of adenosine to inhibit quantal ACh release. This last result implies that TMB-8 and adenosine exert their inhibitory actions at different steps in the depolarization-secretion coupling sequence.
Hunt
J M
JM
Department of Pharmacology, Northwestern University Medical School, Chicago, IL 60611.
Silinsky
E M
EM
Hirsh
J K
JK
Ahn
D
D
Solsona
C
C
D000109:Acetylcholine / Q000378:metabolism*; D000241:Adenosine / Q000494:pharmacology*; D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D005707:Gallic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D066298:In Vitro Techniques; D009045:Motor Endplate / Q000187:drug effects; D009046:Motor Neurons / Q000187:drug effects / Q000378:metabolism*; D011894:Rana pipiens
D002121:Calcium Channel Blockers; D002110:Caffeine; C006014:8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate; D005707:Gallic Acid; D000241:Adenosine; D000109:Acetylcholine