Fig. 4. L-type Ca²⁺ current in burbot ventricular myocytes measured with 5 mmol l^-1 EGTA in the pipette solution. (A) Representative recording at 11°C with and without stimulation by isoprenaline (10 µmol l^-1). Values are means ± s.e.m. from 6-12 cells at 4°C (B) and 11°C (C) under control conditions and in the presence of 10 µmol l^-1 isoprenaline (Iso). ^*Density of I_Ca is increased significantly by 10 µmol l^-1 isoprenaline (Student's t-test, P<0.01). (D) Steady-state activation and inactivation relationships I_Ca at 4°C only. (E) The I_Ca window current (product of activation and inactivation curves in D) at 4°C.