Fig. 2. The effects of acute hypoxia (40 mmHg=5.3 kPa; at the vertical dashed line) on plasma levels of adrenaline (filled columns) and noradrenaline (open columns) in rainbow trout (Oncorhynchus mykiss) previously infused (0.2 ml min–1) with nicotine (1.3x10–5 mol kg–1 h–1) for 60 min under conditions of normoxia. An injection of (A) atropine (1 µmol kg–1; N=9), (B) methysergide (10–8 mol kg–1; N=9) or (C) lisinopril (10–4 mol kg–1; N=20) was administered after 40 min of nicotine infusion. Plasma catecholamine levels were measured at ‘Pre’, 10 min and 60 min of infusion and during acute hypoxia. Values are shown as means + S.E.M. An asterisk denotes a statistically significant increase (P<0.05) from the corresponding ‘Pre’ value or ‘60 min’ pre-hypoxia value. A dagger indicates a statistically significant difference (P<0.05) from the control value (saline injection; Fig. 1B).
