Airway response to adrenergic agonists and antagonists in 3-day- to 2-year-old rats

The response of the airways to adrenergic agonists and antagonists was studied in 3-day- to 2-year-old and bronchitic rats. The results showed that the alpha-adrenoceptors are not functional at birth but become so by 8 weeks. In contrast, the beta-adrenoceptor effects are demonstrable on the third day after birth. The mean decrease in airway luminal diameter after beta-adrenergic blockade was greater in bronchitic than in healthy animals and was interpreted to be due to the increased sensitivity of the beta-adrenoceptors in bronchitis.