Fig. 6. Comparison of the voltage threshold for net inward current in isolated atrial and ventricular myocytes of the rainbow trout heart. (A) Currents were elicited from the holding potential of -82 mV muscle by 30 ms depolarising pulses in 2 mV increments. (B) Representative recordings of whole-cell membrane currents (I_m) from atrial and ventricular myocytes. The horizontal line indicates the zero membrane potential. (C) Mean (± s.e.m.; N=6-9) current-voltage relations of atrial and ventricular myocytes indicating the threshold for the net inward current. Asterisks show a significant difference (P<0.05) between atrial and ventricular myocytes.