title: Activity of putative pulmonary ornithokallikrein and angiotensin-converting enzyme during the onset of lung respiration in the chick embryo.
abstract: We have assayed a proteinase from chicken lungs, the properties of which were comparable to those of ornithokallikrein, the enzyme that catalyzes the formation of ornithokinin. The activity of this pulmonary proteinase showed an accelerated increase during the development of lung respiration (paranatal period). In contrast, the increase in the activity of angiotensin-converting enzyme (ACE), which degrades kinin, was not enhanced at this developmental stage. L-thyroxine administration accelerated the onset of lung respiration and the associated changes in the activities of ornithokallikrein and ACE. Thiourea, on the other hand, retarded the onset of lung respiration. Concomitantly, there was no pronounced increase in ornithokallikrein activity and no attenuation of the increase in ACE activity. Furthermore, the development of lung circulation, as measured by pulmonary hemoglobin concentration, paralleled the ornithokallikrein activity. The results suggest that the increase in ornithokallikrein activity and the suppression of ACE activation during the paranatal period help adapt the embryo to the neonatal period.
mesh_terms: D000818:Animals; D002642:Chick Embryo / Q000201:enzymology / Q000254:growth & development / Q000502:physiology*; D006454:Hemoglobins / Q000032:analysis; D007610:Kallikreins / Q000378:metabolism*; D008168:Lung / Q000098:blood supply / Q000196:embryology / Q000201:enzymology; D007703:Peptidyl-Dipeptidase A / Q000378:metabolism*; D012119:Respiration
chemical_list: D006454:Hemoglobins; D007703:Peptidyl-Dipeptidase A; D007610:Kallikreins