Figure 1.

Effects of denervation on concentration–response curves for the α₁-adrenoceptor agonist, phenylephrine. (A–D) Data are shown for arteries denervated for 2 weeks (A,B) and 7 weeks (C,D), and their control arteries (from sham-operated rats), in the absence (A,C) and in the presence (B,D) of the neuronal noradrenaline uptake inhibitor desmethylimipramine (DMI, 30 nM). In the absence of desmethylimipramine, the phenylephrine concentration–response curves for denervated arteries were shifted to the left of those for the control arteries. Desmethylimipramine shifted the phenylephrine concentration–response curves to the left in control arteries, but did not change those in denervated arteries. In the presence of desmethylimipramine, the phenylephrine concentration–response curve for 2 weeks denervated arteries lay to the left of that for their controls, but the curve for 7 weeks denervated arteries overlay the control curve. P values indicate the significance of the differences between the curves for control and denervated arteries (assessed by analysis of variance). For each group of arteries, n= 6.