Effect of nifedipine on bronchoconstriction induced by inhalation of cold air.

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Abstract
The effect of nifedipine (20 mg sublingually) on the bronchial response to cold air was studied in 8 asthmatic patients and 8 normal subjects. Eucapnic hyperventilation with dry subfreezing air was performed for 3 min by each subject, with a minute volume of 30 .times. FEV1 [forced expiratory volume in 1 s] for normal subjects and half that for the asthmatics. In the normal subjects there was no difference in the falls in FEV1 and specific airways conductance (sGaw) produced by cold air inhalation on the days when they were pretreated with placebo and nifedipine. In asthmatic patients significant protection with nifedipine was demonstrated. The maximum recorded fall in FEV1 was reduced from 13% .+-. 2% (SE) to 4% .+-. 2% (P < 0.005) and the maximum fall in sGaw from 35% .+-. 5% to 17% .+-. 4% (P < 0.002). The possible causes of this difference are discussed. These results present further evidence for a difference mechanism of response to cold air in asthmatic and normal subjects.