Effects of calcium ions and local anaesthetics on electrical properties of Purkinje fibres

Calcium ions and local anaesthetics are said to 'stabilize' excitable membranes. This statement is based on the findings that in the presence of these agents (i) stronger currents are needed to stimulate the tissues, (ii) spontaneous rhythms are slowed or suppressed, (iii) conduction of impulses may be blocked, and (iv) the resting potential remains practically unchanged (for references, see Fleckenstein & Hardt, 1952; Brink, 1954). The present paper describes the action of calcium ions and local anaesthetics on the magnitude of the diastolic membrane potential, the rate of rise and ' overshoot' of the action potential, the threshold potential and the membrane resistance of mammalian Purkinje fibres. A knowledge of such data may contribute to an understanding of the mode of action of these 'stabilizing' agents. METHODS

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