Oxytocic esterase in rat urine

Publisher Website
Google Scholar
Abstract
In rat urine an oxytoclc principle has been found that displays all the properties of an esterase. Besides acting on the uterus it caused a fall in rat and dog blood pressure, but no effect was observed on the guinea pig uterus or ileum, rat duodenum or cecum, or mouse uterus. On rat and guinea pig skin also it had no effect in conditions in which bradykinin and histamine produced increase in capillary permeability. It showed a potent stimulating action on isolated rat uterus comparable to that of acetylcholine. In spite of its capacity to release kinin from plasma, it is suggested that the esterase acts independently of a sub-strate in the uterus, combining directly with receptors in the organ. As diisopropylfluorophosphate abolished the oxytocic action, serine must be an important part of the active center of the enzyme essential for its action on the uterus. Besides oxytocic esterase, the urine also contained an inhibitory factor that could be separated by dialysis from the oxytocic principle. This factor, however, not only inhibited the stimulating action of urine on the uterus but also had some effect against acetylcholine and bradykinin.