Calcium antagonism of anionic liposome actions at a muscarinic synapse.
Addition of 0.5 mM Ca++ to guinea pig ileum longitudinal muscle-myenteric plexus preparation, which is contracted under the influence of anionic liposomes, is followed by a rapid, temporary, relaxation. Such Ca++ addition produces no change in the field-stimulated preparation, eliminating direct Ca++ effects or neuronal acetylcholine release nor in the preparation stimulated by added acetylcholine, eliminating direct Ca++ effects on muscle. These eliminations leave the Ca++ interaction with liposomes, probably causing self-fusion, and loss from interaction with cholinergic neurons, as the mechanism for Ca++-induced relaxation.
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D006168:Guinea Pigs; D007082:Ileum / Q000294:innervation; D008081:Liposomes; D009119:Muscle Contraction / Q000187:drug effects; D009197:Myenteric Plexus / Q000187:drug effects / Q000502:physiology*; D010743:Phospholipids / Q000494:pharmacology*; D011950:Receptors, Cholinergic / Q000502:physiology*; D011976:Receptors, Muscarinic / Q000502:physiology*; D013569:Synapses / Q000187:drug effects / Q000502:physiology*
D008081:Liposomes; D010743:Phospholipids; D011950:Receptors, Cholinergic; D011976:Receptors, Muscarinic; D002118:Calcium