Biological tests showed that bronchial asthma is associated with decreased contents of the endogenous sensitizer of β-adrenoreceptors (ESBAR) and the endogenous blocker of M-cholinoreceptors (EBMCR) and an increased content of the endogenous blocker of β-adrenoreceptors (EBBAR) in the blood and urine of children and adults. These phenomena are considered to be causes of bronchial asthma.

Ability of blood sera from 19 asthmatic children and 56 asthmatic adults to modify reactivity of β-adrenoreceptors and M-cholinoreceptors in isolated smooth muscles of the uterus horns from nonpregnant rats (n = 234) and cow trachea (n = 36) have shown that asthma presence did not change serum myocyte-stimulating activity but reduced the sensitizing activity of β-adrenoreceptors and the blocking activity of M-cholinoreceptors and enhanced the blocking activity of β-adrenoreceptors. The similar changes were also seen in child urine and indicated the decreased level of the endogenous sensitizer of β-adrenoreceptors and the growing level of the endogenous blocker of β-adrenoreceptors in asthma patients and the decreased level of endogenous blocker of M-cholinoreceptors in certain asthmatics. These events could provide asthma occurrence.