Characteristics of the resting and action potentials of the heart muscle fibres in some Insecta species

S.-Rózsa, Katalin and V-Szőke, Ida (1971) Characteristics of the resting and action potentials of the heart muscle fibres in some Insecta species. A Magyar Tudományos Akadémia Tihanyi Biológiai Kutatóintézetének évkönyve, 38. pp. 65-77. ISSN 0365-3005

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Abstract

Electrophysiological characteristics of the heart of Locusta migratoria migratorioides, Mantis religiosa, Phaneroptera nana, Ephippigera ephippiger, Tettigonia viridissima and Gryllotalpa vulgaris were studied by microelectrodes. It was found that the value of the resting potentials varies between 12-40 mV in the different species. The magnitude of the action potentials was 10-50 mV. In all the investigated species both the minimal and the maximal values were registered. The duration of the action potentials was between 30-170 msec. The action potential showed overshoot in each species. The heart chambers located in the different segments did not show different types of potential and there are no constant values of resting and action potentials for the same segment. The pacemaker type of potential was found to be the prevailing form. The pacemaker potentials may originate from latent or dominant pacemakers. In Locusta heart plateau type potential was observed only after the so-called reversal phenomenon. Action potentials with typical delayed repolarization and well developed plateau were registered only from the heart of Mantis and Ephippigera. The form of the potentials depends on the functional state of the heart muscle fibres, and the cells proved to be multifunctional. Reversal reflects the changes of the function of the single cells and in this course the latent pacemaker can turn into dominant one and vice versa, meaning that the type of the potential would vary not only from one cell to another but from time to time also in the same cell. The results seem to prove the supposition about the myogenic origin of the heart rhythm in the investigated Insecta species.

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