Effects of physalaemin on some exocrine secretions of dogs and rats.

1. Physalaemin, an endecapeptide recently found in the skin of the South American amphibian Physalaemus fuscumaculatus, possesses, besides a marked hypotensive action and a powerful sialogogic activity, also a stimulant activity on other exocrine secretions.2. Exocrine structures which were more potently stimulated by the peptide were lacrimal glands and exocrine pancreas. In the anaesthetized dog the threshold lacrimatory dose was 0.05-0.3 mug/kg; in the rat the threshold dose was 2.5-5 mug/kg. The minimum active dose on exocrine pancreas of the dog was 0.05-0.5 mug/kg.3. Physalaemin did not influence the gastric acid secretion of the dog at the maximum tolerated dose (40 mug/kg). Gastric acid secretion of the rat was stimulated very little if at all.4. In the dog the peptide caused some changes in the bile flow which were connected more with contracture of the gall-bladder than with a true secretory stimulant activity. In the rat the peptide was completely ineffective.5. The results obtained after administration of sympatholytic and parasympatholytic agents suggest that the action of the peptide is at least partly independent from the autonomic nervous system.