Fig. 4. The effects of nitric oxide synthase (NOS) inhibition (using a cocktail of 7-NI and L-NAME; N=9; cross-hatched bars) on (A) noradrenaline (unfilled component of bars), adrenaline (filled component of bars) and total catecholamine secretion (sum of noradrenaline + adrenaline) and (B) nitric oxide (NO) secretion in response to electrical stimulation (30 V, 8 Hz) of a perfused posterior cardinal vein preparation of rainbow trout. Values are means ± 1 S.E.M. A dagger denotes a significant difference (P<0.5) between pre-stimulated and stimulated groups. An asterisk denotes a significant difference (P<0.5) between the control (N=6) and inhibitor treated group (cross-hatched).