Fig. 2. The two major K⁺ currents in burbot ventricular myocytes. (A) Background inward rectifier K⁺ current, I_K1. Values are means ± s.e.m. from 6-8 cells at 4°C (black circles) and 11°C (white circles) measured at the beginning of 500 ms square wave pulses that were elicited from the holding potential of -80 mV to voltages between -120 and 40 mV in 20 mV steps (inset). (B) Delayed rectifier K⁺ current, I_Kr, measured as an outward tail current at -40 mV after 5 s depolarising pulses between -80 and 80 mV (inset). Representative recordings at 4°C and mean values (± s.e.m.) from 5-10 cells at 4°C (black circles) and 11°C (white circles). ^*Density of I_Kr is increased significantly by acute warming to 11°C (Student's t-test, P<0.005).