The course of ionic transmembrane currents during cardiac action potentials.
The course of the total transmembrane ionic current (Ii) during a natural action potential (AP) was reconstructed from a family of current traces recorded for single voltage clamp depolarization steps to various levels. The experiments were performed on 9 papillary cat muscles driven at 0.5 per second in oxygenated 31 degrees C Tyrode. Under varying experimental conditions very good agreement was found between the resulting Ii curve and another indicator of Ii, the first time derivative of the AP (dV/dt). Furthermore, the coefficient needed to adjust dV/dt to reconstructed Ii may serve as an indicator of the membrane capacity. The results suggest the validity of the employed approximation and, in general, the adequacy of the sucrose gap technique applied to cardiac muscle.
D000200:Action Potentials; D000818:Animals; D002415:Cats; D006321:Heart / Q000502:physiology*; D000860:Hypoxia / Q000503:physiopathology; D008564:Membrane Potentials; D009200:Myocardial Contraction; D010210:Papillary Muscles / Q000503:physiopathology