Release of acetylcholine from fragments of human term placenta and effects of the choline acetyltransferase inhibitor (2-benzoylethyl)trimethylammonium iodide.
Intact tissue from human term placenta contained 102 +/- 17 (n = 8) nmoles of acetylcholine (ACh)/g fresh tissue when analyzed by pyrolysis gas chromatography (GC). Free-hand dissection followed by extensive washing led to reductions of tissue ACh content (57 +/- 11 nmoles/g; n = 5) presumably as a result of release into the bathing medium. Presence or absence of physostigmine as an anticholinesterase agent in all solutions used had no significant effect on the ACh content of intact fragments immediately after dissection. Upon incubation at 37 degrees C a new steady state ACh concentration was established within 40-50 min (177 +/- 14 nmoles/g; n = 11) which reflected the content typical for purified villus. ACh was released continuously in amounts linearly related to incubation time up to 80 min, the longest time point examined. When the incubation volume was doubled there was an apparently immediate significant effect on release of ACh. Thereafter liberation of ACh continued at the rate observed prior to the volume perturbation. The stable choline acetyltransferase inhibitor (2-benzoylethyl)trimethylammonium (BETA) inhibited the enzyme rapidly and almost completely in tissue fragments. The drug affected the rate of ACh release significantly 40 min after addition to the bathing solution. At the same time it led to a depletion of the total ACh content that could be extracted from human placenta fragments.
D000109:Acetylcholine / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000494:pharmacology; D002795:Choline O-Acetyltransferase / Q000037:antagonists & inhibitors*; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D013997:Time Factors
C017058:(2-benzoylethyl)trimethylammonium; D002795:Choline O-Acetyltransferase; D000109:Acetylcholine