[Comparative studies on the sensitivity of smooth bronchial muscles to catecholamines during sensitization with...

An attempt has been made to compare the effects produced by adrenergic agents on smooth bronchial muscles of normal and BCG- as well as ovalbumin-sensitized guinea pigs. The method of determining the state of relaxation of the isolated bronchial tree was used to ascertain the degree of sensitivity to adrenergic agents of smooth bronchial muscles. Experiments conducted on a total of 34 guinea pigs showed a considerable decrease in the response of smooth bronchial muscles to novodrine, adrenaline, and noradrenaline subsequent to BCG and ovalbumin sensitization of experimental animals. In normal guinea pigs, minimal relaxation of smooth tracheal muscles was brought about by 7.10(-8) - 1.10(-7) G/ml novodrine, 1.10(-7) - 9.10(-7) g/ml adrenaline, and 1.10(-6) - 8.10(-6) g/ml noradrenaline. For BCG-sensitized animals, the data obtained were 3.10(-7) - these agents of smooth bronchial muscles of guinea pigs was more clearly evident in BCG-sensitized 2.10(-6) g/ml, 1.10(-6) - 2.10(-6) g/ml, and 3.10(-6) - 6.10(-6) g/ml, respectively. The decrease in sensitivity to bronchi during the process of sensitization is believed to be responsible for the decrease in response to animals than in ovalbumin-sensitized guinea pigs. A partial blockade of beta-adrenergic receptors of catecholamines. The degree of partial blockade is dependent upon the kind of sensitization.