Fig. 6. Tension recordings showing the vasodilatory effect of nicotine on the dorsal aorta with an intact endothelium (A) and without an endothelium (B). Vessels were pre-constricted with endothelin-1 (ET-1; 10^–8 mol l^–1), and at the point of maximal vasoconstriction nicotine (3x10^–4 mol l^–1) was administered. Similar results were observed in the intestinal vein. (C) Mean response (% vasodilation) of nicotine on pre-constricted dorsal aorta and intestinal vein with the endothelium removed (filled bars) and with an intact endothelium (open bars). Note that there is no significant difference in the nicotine-mediated dilation (dorsal aorta, P=0.944; intestinal vein, P=0.902; N=5).