Vasoactive intestinal peptide as a bronchodilator in asthmatic subjects

Vasoactive intestinal peptide (V.I.P.) caused bronchodilatation in 7 asthmatic volunteers when given intravenously at the rate of 6 pmol kg-1 min-1 for 15 minutes during a double blind study. Mean baseline FEV1 was 2.8 (+/- 0.3 S.E.) which was 81% of predicted and increased by 0.21 (range 0.1-0.45) l after 15 minutes infusion (p greater than 0.02). Tachycardia and cutaneous flushing were also observed during the infusion. Subsequent induced bronchoconstriction with a predetermined dose of histamine was ameliorated at 180 seconds following challenge when compared with placebo. Mean fall in FEV1 0.26 compared with 0.741 when pre-infusion FEV1 was taken on baseline. Mean fall in FEV1 0.49 l compared with 0.75 l when the FEV1 immediately preceding challenge was used on baseline (p greater than 0.02). The demonstration that V.I.P. is a bronchodilator in asthmatics and ameliorates histamine induced bronchoconstriction has important implications for the pharmacology of asthma.