Fig. 3. Plasma levels of adrenaline (filled columns) and noradrenaline (open columns) during acute hypoxia (40 mmHg=5.3 kPa) 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. To block specific receptors or enzymes, injections were administered at 40 min (20 min prior to hypoxia) using saline (control; N=17), atropine (muscarinic receptor antagonist; 1 µmol kg–1; N=9), methysergide (serotonin receptor antagonist; 10–8 mol kg–1; N=9) or lisinopril (angiotensin-converting enzyme inhibitor; 10–4 mol kg–1; N=20). Values are shown as means + S.E.M. A dagger indicates a statistically significant difference (P<0.05) from the control value.
