Effect of biologically active substances on the spontaneous electrical activity of the heart muscle cells of Helix pomatia L.

Kiss, Tibor and S.-Rózsa, Katalin (1972) Effect of biologically active substances on the spontaneous electrical activity of the heart muscle cells of Helix pomatia L. A Magyar Tudományos Akadémia Tihanyi Biológiai Kutatóintézetének évkönyve, 39. pp. 29-38. ISSN 0365-3005

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Abstract

Resting and action potentials were registered from isolated ventricle of Helix heart by the aid of microelectrodes. The changes of the frequency of potential generation as well as that of the amplitude and shape of the action potentials were studied under the influence of different biologically active substances and of the perfusate collected from the heart during excitatory influence of the extracardial nerve. Acetylcholine (ACh) had biphasic effect: at low concentrations (10⁻¹⁰—10⁻⁸ M) it increased while in higher concentrations (10⁻⁷—10⁻⁵ M) it decreased the frequency of the action potentials. At a concentration 10⁻⁴ M ACh inhibited the generation of the action potentials. 5-hydroxytryptamine (5HT) beginning from the concentration 10⁻¹⁰ M increased the amplitude and the duration of the action potentials, however decreased the frequency of potential generation. The perfusate of the excited heart influenced the action potentials of myocardial cells similarly to 5HT. Adrenaline, noradrenaline and GABA increased the frequency to a less degree with simultaneous decrease in amplitude and rate of rise of the ascending phase of action potentials. Dopamine increased both amplitude and rate of rise of the action potentials. On the basis of the high sensitivity of the membrane of the myocardial cells of Helix heart to ACh, 5HT and dopamine the above agents are supposed to take part in the regulation of heart activity of this species.

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