Figure 1.

Cumulative concentration contraction response curves to PE in (a) endothelium-intact, (b) endothelium-denuded and (c) endothelium-intact rat aortic rings in the presence of 0.1 mM L-NOARG. The ordinate scale represents contraction expressed as g tension produced per mg of tissue. Each data point represents the mean±s.e.mean; the s.e.means are only included when they exceed the size of the symbol. The line has been drawn by interpolation through these mean values. The best fit values for EC₅₀, maximum tension and Hill slope were derived by a computerized non-linear curve fitting procedure for each vessel segment and these mean values are presented in Table 1.