Fig. 7. The effects of systemic injection of different doses of adrenaline and of 100 nmol kg^-1 adrenaline after pretreatment with sotalol (3 mg kg^-1) on breathing frequency, breathing amplitude and total ventilation. The data are shown as the mean + S.E.M. (N=6). Asterisks indicate values that are significantly different from control values. All values were taken 30 s after injection except the 100 nmol kg^-1 adrenaline+sotalol values, which were taken 120 s after injection.