ATRIAL-NATRIURETIC-PEPTIDE, BRADYKININ, AND ANGIOTENSIN II-LIKE IMMUNOREACTIVITY IN THE HARDERIAN-GLAND OF THE TERRAPIN PSEUDEMYS-SCRIPTA -RESPONSE TO OSMOTIC-STRESS

The Harderian gland of the terrapin Pseudemys scripta has four types o f acinar cells. Type IV cells are very similar to the salt secreting c ells of the salt secretory glands of various marine vertebrates. The p resence and localization of the Ile(5)-Angiotensin II, Atrial Natriure tic Peptide, and Bradykinin has been investigated by immunohistochemic al methods. Immunoreactivity is confined to the type IV cells. Changes in the environmental salinity resulted in different patterns in the i mmunoreactivity especially after incubation with Ab-Angiotensin II and Ab-Atrial Natriuretic Peptide. Immunoreactive Angiotensin II cells ar e more numerous in animals maintained in distilled water, when reabsor ption of sodium is needed. In contrast, immunoreactive Angiotensin II cells are very few in animals maintained in seawater. On the contrary, the number of immunoreactive cells for Atrial Natriuretic Peptide is high in seawater maintained animals, and weaker in animals in distille d water. The type ni cell may be considered a candidate for ion regula tion in the terrapin Harderian gland. (C) 1996 Wiley-Liss, Inc.