Respiratory response to carbon dioxide after propranolol in normal subjects

The ventilatory response to carbon dioxide, using the rebreathing technique, was investigated in 5 healthy nonsmoker volunteers, without obstructive bronchopathy. The administration of propranolol (20 mg) in a single oral dose did not produce significant modifications of the slopes of the response curves, but caused a significant increase of the intercept of the curves (p less than 0.05). Since no changes of the spirographic values were noted, the results obtained were attributed to a decrease of ventilation. It is concluded that propranolol, even at the dose of 20 mg, is able to induce a depression of the respiratory center, concomitant with significant reduction of heart rate and arterial blood pressure.