title: [Vagus effect on action potentials of rest-potentiated contractions in the isolated left atrium of the rabbit].
abstract: After a period of rest action potentials in constantly driven preparations of left rabbit atria show a marked change in configuration. After the upstroke an early repolarization takes place which is followed by a prolonged phase of secondary depolarization. This depolarization is strongly suppressed by vagal stimulation. Frequency-response characteristics of this electrotropic effect were obtained by stimulating the vagal supply of the preparation with frequencies in the range from 1.0 to 40.0 s-1 and compared with those of the constantly driven preparation. In most cases studied the frequency-response curves for the post rest action potential are steeper in rise and shifted to the left. By placing a series of vagal stimulations at different moments into the resting interval vagal effects could be composed to reflect the time course of transmitter action in a non beating preparation. It was shown that such time course is not essentially altered compared with that of a driven preparation. From a mathematical treatment of the frequency-response relations it is concluded that post rest action potentials show a higher sensitivity towards the transmitter action and that the amount of transmitter liberated after a period of rest may be increased. Possible explanations for this behaviour are proposed.
mesh_terms: D000200:Action Potentials; D000818:Animals; D016275:Atrial Function; D004558:Electric Stimulation; D006325:Heart Atria / Q000294:innervation; D066298:In Vitro Techniques; D009200:Myocardial Contraction; D018377:Neurotransmitter Agents / Q000502:physiology; D011817:Rabbits; D012146:Rest; D014630:Vagus Nerve / Q000502:physiology*
chemical_list: D018377:Neurotransmitter Agents
vernacular_title: Die Vaguswirkungen auf das Aktionspotential des isolierten linken Kaninchenovorhofs bei pausenpotenzierten Kontraktionen.