Increased release of [3H]acetylcholine in vitro from the mouse hippocampus by a convulsant barbiturate.
The effects of the convulsant barbiturate, 5-(2-cyclohexylidene-ethyl)-5-ethyl barbituric acid (CHEB), on the spontaneous release of [3H]acetylcholine (ACh) from mouse hippocampal slices in an in vitro superfusion system have been evaluated. The pattern of the release of [3H]ACh by a single treatment with CHEB or an elevated potassium concentration was similar, with the peak release occurring in the same fraction. A maximally effective concentration of CHEB (500 microM) caused a 177% stimulation of spontaneous release of [3H]ACh, while 50 mM KCl increased the release by 2100% above the baseline. The stimulation of the spontaneous release of [3H]ACh by CHEB was concentration-dependent with an EC50 of 180 microM. The pattern of release of [3H]ACh induced by multiple treatment with CHEB and elevated potassium appeared to differ, suggesting that different pools of [3H]ACh in the cholinergic neurons might be affected by these treatments. The action of CHEB on the spontaneous release of [3H]ACh was unique among some other convulsant drugs that were studied. Another convulsant barbiturate, S(+)-1-methyl-5-phenyl-5-propyl barbituric acid [S(+)-MPPB], pentylenetetrazol and a convulsant benzodiazepine 1,3-dihydro-5-methyl-2H-1,4-benzodiazepine-2-one (Ro-5-3663) did not affect the spontaneous release of [3H]ACh. The relationship between the stimulation of release of ACh and the convulsant action of the barbiturates is discussed.
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D001463:Barbiturates / Q000031:analogs & derivatives / Q000494:pharmacology*; D001522:Behavior, Animal / Q000187:drug effects; D003292:Convulsants / Q000494:pharmacology*; D004558:Electric Stimulation; D006624:Hippocampus / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D011188:Potassium / Q000494:pharmacology
D001463:Barbiturates; D003292:Convulsants; C024321:5-(2-cyclohexylidene-ethyl)-5-ethylbarbiturate; D000109:Acetylcholine; D011188:Potassium