title: Effects of synaptic plasma membranes on release of acetylcholine from synaptic vesicles.
abstract: The influences of synaptic plasma membranes on release of acetylcholine (ACh) from synaptic vesicles isolated from rat brain were examined. In the presence of ATP, Mg++ and Ca++ but absence of cytoplasm from the nerve endings, the synaptic plasma membranes did not increase ACh release indicating absence of a stimulating factor which is known to be present in the cytoplasm. In presence of ATP, Mg++, Ca++ and the cytoplasm, the synaptic plasma membranes inhibited ACh release from the synaptic vesicles in high K+ medium, though not in high Na+ medium. Binding of Ca++ by the synaptic plasma membranes was dependent on ATP, inhibited by Na+ and stimulated by K+. Thus, the synaptic plasma membranes may inhibit ACh release in high K+ medium due to reduction in the concentration of free Ca++.
mesh_terms: D000109:Acetylcholine / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001921:Brain / Q000166:cytology; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D003593:Cytoplasm / Q000502:physiology; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D011485:Protein Binding; D051381:Rats; D013570:Synaptic Membranes / Q000378:metabolism / Q000502:physiology*; D013572:Synaptic Vesicles / Q000378:metabolism*
chemical_list: D000255:Adenosine Triphosphate; D008274:Magnesium; D000109:Acetylcholine; D011188:Potassium; D002118:Calcium