[Properties of vagal excitation transfer to the heart atrium].
A mathematical model of pre- and postganglionic parasympathetic nerve fiber excitation transfer is developed. This model gives a measure Q of acetylcholine (ACh) release from presynaptic preganglionic boutons and postganglionic varicosities. When increasing Ca++ the measure Q increases too. Na-ions exert a competitive inhibition. The relationship between Q and the Ca/Na2-quotient is a hyperbolic one. Mn++ inhibits the release of ACh non-competitively. Q increases both by excess potassium and Cs+ depolarization. The ACh release is diminished by Mg++. Ba++ cannot replace the effect of Ca++ on ACh release in Ca++ depleting conditions. Q increases with decreasing pH-level. The ACh release is not significantly influenced by increasing pH, Verapamil (4 mg/l), prostaglandins E2 and F2alpha (20 ng/ml) and substitution of nonpermeable anions for Cl-.
D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D016275:Atrial Function; D002118:Calcium / Q000494:pharmacology; D002413:Cations, Divalent; D006325:Heart Atria / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008345:Manganese / Q000494:pharmacology; D008433:Mathematics; D011453:Prostaglandins / Q000494:pharmacology; D011817:Rabbits; D012964:Sodium / Q000494:pharmacology; D014630:Vagus Nerve / Q000187:drug effects / Q000502:physiology*; D014700:Verapamil / Q000494:pharmacology
D002413:Cations, Divalent; D011453:Prostaglandins; D008345:Manganese; D012964:Sodium; D014700:Verapamil; D000109:Acetylcholine; D002118:Calcium
Eigenschaften der vagalen Erregungsübertragung auf das Vorhofmyokard.