Fig. 3. (A) Tension recording showing the vasodilatory effect of sodium nitroprusside (SNP) on the intestinal vein. The vessels were preconstricted with endothelin-1 (ET-1; 10^–8 mol l^–1) and at the point of maximum constriction, SNP (10^–4 mol l^–1) was added, which caused a marked dilation. Similar results were observed in the dorsal aorta. (B) Mean responses (% vasodilation) of preconstricted dorsal aorta and intestinal vein to SNP (10^–4 mol l^–1; N=5).