Adrenoceptor responsiveness in bronchial asthma: effect of isoprenaline inhalation on plasma cyclic 3',5'-AMP levels.

The effect of isoprenaline inhalation on plasma levels of cyclic AMP has been studied in a group of normal subjects and compared to a group of asthmatics. The normal subjects had a prompt rise in their plasma cyclic AMP level, and when compared to the asthmatic group, had a significantly greater percentage rise in plasma cyclic AMP from the basal levels. The markedly attenuated response to isoprenaline inhalation in the asthmatic group is consistent with the concept that asthmatics have a relative impairment of beta-adrenoceptor function. These results support the in vitro studies demonstrating that lymphocytes from asthmatic subjects incubated with isoprenaline produce less cyclic AMP than those from normal subjects.