Fig. 1. (A) The effects of continuous infusion of control saline (unfilled bars; N=8) or rapidly switching to saline containing nicotine (10^–5 mol l^–1; filled bars; N=8) or nicotine plus hexamethonium (10^–3 mol l^–1; cross-hatched bars; N=8) on catecholamine secretion in an in situ perfused posterior cardinal vein preparation of rainbow trout Oncorhynchus mykiss. (B) After 10 min, the preparations were electrically stimulated using a frequency of 20 Hz and maximal catecholamine secretion rates were determined under the various conditions. An asterisk denotes a statistically significant difference from the `pre-switch' (Pre) value; a dagger represents a significant difference from the secretion rate after 10 min; a double dagger represents a significant difference from the control (saline-perfused) group.

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