Beta1-blocker (practolol) and exercise in patients with chronic obstructive lung disease.

Ventilatory and circulatory data from 20 patients suffering from chronic obstructive lung disease have been obtained before, during and after exercise at 600 kpm/min for 5 min on a bicycle ergometer. The patients had been given intravenously practolol, 15 mg, or saline alternatively, using a double-blind cross-over technique. A slight postexercise reduction of FEV1 (8%) was noted after practolol medication as compared to placebo, with an accompanying decrease in PaCO2; PaO2 did not differ substantially. No wheezing or inappropriate dyspnea attributable to the medication was noted in any of the patients. The well known beta1-blocking effects on the circulation were confirmed, with maintained Q and reduced HR, together with a lowered systemic BP during and after exercise. There was a significant positive relationship between the postexercise reduction of FEV1 and the concomitant fall in HR. It is concluded that practolol in doses with near maximal circulatory effects had a slight, but clinically insignificant effect on the ventilatory parameters.