[Effect of atropine and pirenzepine on bronchoconstriction during vagus nerve stimulation in dogs]

The effects of atropine or pirenzepine on bronchoconstriction and reduction in heart rate during vagus nerve stimulation were studied in 10 anesthetized dogs. The bronchoconstriction produced by electrical stimulation of the vagus nerves, 5 min after intravenous injection of atropine or pirenzepine, was recorded as an increase in pulmonary inflation pressure. Atropine and pirenzepine at the doses of 0.01 mg.kg-1 and 0.2 mg.kg-1 respectively were administered and supplemented twice at 30 min intervals. Atropine inhibited the reduction in heart rate more than pirenzepine at all doses. Pirenzepine inhibited the increase in pulmonary inflation pressure more than atropine. Our results suggest that pirenzepine which inhibits bronchoconstriction is useful in patients with bronchial asthma and/or COPD as an anticholinergic agent.