Cellular membrane potentials and contractility of normal rat atrium and the effects of temperature, tension and stimulus frequency

Simultaneous recording of membrane potentials and contractility in isolated rat atria by means of intracellular micro-electrodes and a sensitive strain gage has been used to establish the normal characteristics of the tissue as well as effects of temperature, stimulus frequency and initial tension on muscle. Preliminary correlations between duration of the action potential and the degree of contraction indicate that the rate of repolarization is of major importance in determination of the contractile response.