title: Effect of divalent cations on acetylcholine release from cardiac parasympathetic nerve endings.
abstract: The influence of several divalent cations on acetylcholine (ACh) release from vagus nerve terminals was studied in quiescent guinea-pig auricles. ACh release was induced by stimulus trains subthreshold for excitation of atrial cells. The ACh released evoked a hyperpolarization of the atrial cell membrane. Changes in ACh sensitivity of the atrial cell membrane were tested by application of ACh-containing solutions. ACh release increased with the external Ca concentration. External Sr maintained the ACh release in 'Ca-free' media. However, Sr ions were less effective than Ca ions. External Mg acted as a weak inhibitor of the stimulus evoked ACh release, whereas Co and Mn ions exerted a strong inhibition.
mesh_terms: D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D016275:Atrial Function; D002118:Calcium / Q000494:pharmacology; D002413:Cations, Divalent; D003035:Cobalt / Q000494:pharmacology; D006168:Guinea Pigs; D006325:Heart Atria / Q000294:innervation*; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology; D008345:Manganese / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D014630:Vagus Nerve / Q000378:metabolism*
chemical_list: D002413:Cations, Divalent; D003035:Cobalt; D008345:Manganese; D008274:Magnesium; D000109:Acetylcholine; D002118:Calcium