Fig. 3. Force and relaxation restitution of the burbot atrial and ventricular muscle in the absence (open symbols) and presence (filled symbols) of 10 µmoll^-1 ryanodine. F_ES (A) and dF/dt_min (B) are plotted as a function of the extrasystolic interval (t) and the plots were fitted by single exponential equations. Values are means ± S.E.M. of 5 preparations. The experiments were conducted at 1±0.5°C. See Materials and methods for details.