Fig. 4. The effects of acute hypoxia (40 mmHg=5.3 kPa) on plasma angiotensin II levels in rainbow trout (Oncorhynchus mykiss) previously infused (0.2 ml min^–1) with nicotine (1.3x10^–5 mol kg^–1 h^–1) or saline (data were combined as there were no significant differences in [angiotensin II] between the two groups) for 60 min under conditions of normoxia. An injection of saline (filled columns; N=15) or lisinopril (10^–4 mol kg^–1; open columns; N=15) was made prior to hypoxia at 40 min infusion. ‘Pre’ samples were taken immediately prior to the onset of hypoxia. Values are shown as means + S.E.M. An asterisk denotes a statistically significant increase (P<0.05) from the corresponding ‘Pre’ value. A dagger indicates a statistically significant difference (P<0.05) from the control value.