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  • Title: [Vagus effect on action potentials of rest-potentiated contractions in the isolated left atrium of the rabbit].
    Author: Weiss E.
    Journal: Acta Biol Med Ger; 1980; 39(5):571-6. PubMed ID: 6108665.
    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.
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