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Br J Clin Pharmacol. 1999 Sep;48(3):336-44.

Substance P-induced vasodilatation is mediated by the neurokinin type 1 receptor but does not contribute to basal vascular tone in man.

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Clinical Pharmacology Unit and Research Centre, University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, Scotland, UK.



Following intravenous administration of its prodrug, L-758,298, we assessed the pharmacodynamics of L-754,030, a novel and highly selective NK1 receptor antagonist, by examining systemic haemodynamics and the blood flow responses to intra-arterial substance P infusion.


Sixteen healthy male volunteers participated in a double-blind, randomised, placebo controlled crossover trial of L-758 298. Forearm blood flow was measured using venous occlusion plethysmography during intrabrachial substance P infusion (0.125-128 pmol min-1 ). In part 1, eight subjects received substance P infusions before and during placebo, 0.25 mg, 1 mg or 5 mg of L-758 298. In part 2, eight subjects received substance P infusions 24 h after placebo or 1.43 mg of L-758 298.


L-758 298 caused dose dependent inhibition of substance P induced vasodilatation (P<0.001). Placebo adjusted differences (95% CI) in baseline forearm blood flow, mean arterial pressure and heart rate showed no relevant changes with 5 mg of L-758 298 (>1400-fold shift in substance P response): 0.00 (-0.49 to +0.49) ml 100 ml-1 min-1, 1. 0 (-3.2 to +5.2) mmHg and 1.9 (-5.9 to +9.7) beats min-1, respectively. Twenty-four hours after 1.43 mg of L-758,298, there was approximately 34-fold shift in response to substance P induced vasodilatation (P<0.008) at plasma L-754 030 concentrations of 2-3 ng ml-1. L-758 298 was generally well tolerated without serious adverse events.


Substance P induced forearm vasodilatation is mediated by the endothelial cell NK1 receptor in man but endogenous substance P does not appear to contribute to the maintenance of peripheral vascular tone or systemic blood pressure.

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