Abstract
It has been reported that bronchoconstrictor effect of a certain spasmogen is modified by release of catecholamines. According to McCulloch et al. (1), these catecholamines are released in guinea pigs by histamine as a result of a sympathetic bronchodilator reflex. Collier et al. (2) assumed that bradykinin or angiotensin directly liberates catecholamines from the adrenal glands of guinea pigs. In cats, Colebatch (3) proposed similar mechanism to that of Collier et al. (2) on the constriction of alveolar ducts produced by histamine. Thus it seems that the source of catecholamines, which affect the bronchoconstriction, varies with sort of spasmogens or with species of animals.
The present experiments were undertaken to examine the role of autonomic nervous system or humoral regulation involved in the bronchoconstriction induced in cats by histamine, which was administered intravenously (4, 5). Besides histamine, acetylcholine and serotonin were also used as bronchoconstrictor agents. In addition, bronchoconstriction induced in guinea pigs by histamine was studied and the results were compared with that of cats.
