Time course of recovery of beta- and alpha 1-adrenoceptors in experimental asthma

1. The time course of recovery of reduced beta-adrenoceptors caused by ovalbumin (OA) challenge was investigated using guinea-pigs. 2. The effects of prednisolone on the recovery time course were also evaluated. 3. beta- and alpha 1-receptor assays were performed using lung membranes. Adenylate cyclase activity was also measured. 4. OA challenge reduced the number of beta-adrenoceptors by 35%, and a significant decrease (13%) persisted for 7 days. The number of beta-adrenoceptor recovered after 14 days. 5. OA challenge elevated the number of alpha 1-adrenoceptors. A significant increase (24%) was observed after 7 days, and it took a further 7 days for the recovery. 6. After OA challenge there was a significant decrease in adenylate cyclase activity after 7 days, which recovered after a further 7 days. 7. Inhalation of prednisolone accelerated the recovery of beta-adrenergic responsiveness, though it did not affect the recovery of the number of alpha 1-adrenoceptors. Prednisolone inhalation also elevated beta-adrenergic responsiveness in non-asthmatic subjects. 8. It is concluded that reduced beta-adrenergic responsiveness caused by OA challenge persisted for 7 days and recovered after a further 7 days. Steroid hormone increased beta-adrenoceptors.