Fig. 7. Tension recordings from the dorsal aorta showing the vasodilatory effect of nicotine (A), and its effect in the presence of the specific nNOS inhibitor N-propyl-L-arginine (PLA) (B). Vessels were pre-incubated with PLA (10^–5 mol l^–1) for approximately 10 min prior to being pre-constricted with endothelin-1 (ET-1; 10^–8 mol l^–1). At the point of maximal vasoconstriction, nicotine (3x10^–4 mol l^–1) was added. Note that the vasodilation is reduced in the presence of PLA. (C) Mean response (% vasodilation) of nicotine on pre-constricted dorsal aorta and intestinal vein in the in the presence of (filled bars) and in the absence of PLA (open bars). Note that PLA significantly reduced the nicotine-mediated dilation (dorsal aorta and intestinal vein, P<0.05; *denotes significant difference; N=5).