TACHYKININ NK1 RECEPTOR-MEDIATED VASORELAXATION IN HUMAN PULMONARY-ARTERIES

Tachykinin NK1 receptors are present on human pulmonary arteries. Addi tion of the specific tachykinin NK1 receptor agonist, [Met-OMe11]subst ance P produced a concentration-dependent relaxation (0.1 nM to 100 nM ) in pulmonary arteries preconstricted with phenylephrine (30 mu M). T he EC50 (agonist concentration needed to produce 50% of the maximal re laxation) value for [Met-OMe11]substance P was 3.7 +/- 0.7 nM. The rel axation induced by [Met-OMe11]substance P was selectively inhibited by the tachykinin NK1 receptor antagonist CP 99994 (1 nM), with a pK(b) of 9.9 +/- 0.3. Treatment with the tachykinin NK1 receptor antagonist SR 48968 (100 nM) did not significantly affect the vasorelaxation due to [Met-OMe11]substance P (P > 0.05, one-way analysis of variance; ANO VA). (C) 1998 Elsevier Science B.V. All rights reserved.