Stimulation of acetylcholine output from brain slices caused by the ionophores BrX-537A and A23187.
1 The effect of two ionophores, BrX-537A (Bromolasolacid) and A 23187, on acetylcholine (ACh) output from brain slices was studied. 2 The slices were prepared from rat cerebral cortex, incubated in Krebs solution containing physostigmine and ACh output determined by bioassay. 3 Both ionophores enhanced ACh output. BrX-537A exerted its maximal effect, a six fold increase, at a concentration of 1.8 micron, while A 23187 caused a three fold increase at a concentration of 58 micron. 4 When the slices were incubated in a Ca-free medium, the effect of A 23187 on ACh output was only reduced, BrX-537A was abolished while that of BrX-537A was also active when disodium edetate (EDTA) was added to the the Ca-free medium. 5 The activity of BrX-537A was not affected by the presence of tetrodotoxin in the incubation medium. 6 The stimulation of ACh output elicited by KCl (25 mM) was increased further by hyoscine, but not by BrX-537A. Hyoscine however had no effect when ACh output was stimulated by BrX-537A. 7 The effect of BrX-537A on ACh output was potentiated by the addition of Mg2+ (9.3 mM) to the incubation medium and was reduced in a Mg-free medium. 8 It is concluded that A 23187 stimulates ACh output by transporting extracellular Ca2+ into cholinergic nerve endings. The effect of BrX-537A does not depend only on Ca2+ but also on other mechanisms.
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001921:Brain / Q000378:metabolism*; D000001:Calcimycin / Q000494:pharmacology*; D004492:Edetic Acid / Q000494:pharmacology; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007832:Lasalocid / Q000031:analogs & derivatives / Q000494:pharmacology*; D008274:Magnesium / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D012601:Scopolamine / Q000494:pharmacology; D013268:Stimulation, Chemical; D013779:Tetrodotoxin / Q000494:pharmacology; D013997:Time Factors
D000900:Anti-Bacterial Agents; D000001:Calcimycin; D013779:Tetrodotoxin; D011189:Potassium Chloride; D004492:Edetic Acid; D012601:Scopolamine; D008274:Magnesium; D000109:Acetylcholine; D007832:Lasalocid