FIG. 1.

Ketanserin and GR-55562 inhibit 5-HT-mediated pulmonary arterial contractility. Dose response curves of pulmonary arterial rings exposed to 1 nM to 100 μM of 5-HT in an additive manner from (A) normoxic and (B) LTH sheep. Solid lines indicate absence of any antagonists (Control). Dotted lines indicate presence of 100 nM ketanserin (boxes) or 1 μM GR-55562 (triangles). Curves are plotted in relation to the maximal contraction induced by initial stimulation of 125 mM K+K-H solution (%TKmax). (C) Bars (open: normoxic; solid: LTH) indicate mean±S.E.M. of EC50 values for each dose response curve depicted in (A) and (B). *p<0.05, ***p<0.001 denotes significant difference by 2-way ANOVA.