Study summary · research use only
Effect of vasoactive intestinal peptide (VIP) on propranolol-induced bronchoconstriction.
Abstract
There is now considerable evidence in favor of vasoactive intestinal peptide (VIP) as a neurotransmitter of nonadrenergic noncholinergic nerves in the airways. The purpose of our study was to evaluate the influence of inhaled VIP on bronchomotor tone after a beta-adrenergic- and cholinergic-receptor blockage. The study was performed in six patients with asthma in 4 days. On the first day, a propranolol provocative dose producing a 20% change in FEV1 (PD20) was determined from the individual semilogarithmic dose-response curve. On the other days, the propranolol challenge was performed after inhalation of ipratropium bromide (40 micrograms), VIP (70 micrograms), and both drugs in randomized double-blind order. Statistical analysis was performed by two-way analysis of variance. The results demonstrated that mean propranolol PD20 was 0.14 mg (geometric mean + SD = 1.22). Ipratropium bromide administration, like VIP administration, significantly raised the PD20 value. The administration of both drugs elicited a further remarkable increase of mean propranolol PD20. The results demonstrated that inhaled VIP influences bronchomotor tone and that this effect is independent of the cholinergic blockage.
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