Pharmacological actions of eledoisin on extravascular smooth muscle

Some general effects and the action of eledoisin on a number of isolated smooth muscle preparations have been studied. It has been found that eledoisin possesses a potent stimulating action on all preparations of gastro-intestinal smooth muscle examined and also on the bronchial muscle of the guinea-pig in situ. Preparations of other smooth muscles were less sensitive. The rabbit colon, the guinea-pig ileum and, subordinately, the rabbit uterus and the frog stomach may be profitably used, owing to their sensitivity and the satisfactory dose/response relationship, for the quantitative bioassay of eledoisin in crude or pure preparations of the polypeptide. In parallel assays eledoisin could be easily distinguished from the biogenic amines and from all other known naturally occurring hypotensive polypeptides (bradykinins, wasp kinin, bradykinin-like polypeptides of the amphibian skin, physalaemin, substance P). In the unanaesthetized dog, subcutaneous doses of 25 to 100 μg/kg eledoisin caused a powerful stimulation of the motility and some secretions of the alimentary canal. This effect was much less pronounced in the rat and the rabbit.