Effects of verapamil on histamine-induced changes in lung mechanics

The effects of verapamil on airway resistance and total thoracic compliance were studied in 15 rabbits with histamine-induced changes in lung mechanics. The animals, after being tracheotomized under anaesthesia, were subjected to mechanical ventilation in a time-cycled, volume-limited mode. Airway pressure and gas flow signals measured by a pneumotachograph and integrated for volume, were registered on a recorder. Each animal was given histamine hydrochloride in an isotonic solution of sodium chloride at a rate of 0.05 micrograms.kg-1.min-1 through a peripheral venous line. Verapamil was infused intravenously in an isotonic solution of sodium chloride at a rate of 20 micrograms.kg-1.min-1 after the initiation of histamine. Verapamil reduced the histamine-induced increase in airway resistance by 20% at 20 min after the start of administration.