Fig. 1. Comparisons of vascular response to acetylcholine (A ) or norepinephrine (B-D ) between control (nondiabetic, open circles ) and diabetic (closed circles ) rats. (A ) Comparison of the vasodilator response to acetylcholine in endothelium-intact (+E) strips precontracted with 10 μm norepinephrine (NE). (B , C ) Comparisons of the contractile response to norepinephrine in +E (B ) or −E (C ) strips. (D ) Comparisons of the contractile response to norepinephrine in −E strips from control rats with that in +E strips from diabetic rats, n = 12. *P < 0.05 versus  control at each concentration.