SECRETION OF ENDOGENOUS OUABAIN FROM BOVINE ADRENOCORTICAL-CELLS - ROLE OF THE ZONA GLOMERULOSA AND ZONA-FASCICULATA

Recent experiments have demonstrated the secretion of a ouabain-like c ompound from primary cultures of bovine adrenocortical cells (1). To d etermine the relative contribution of the outer zones of the adrenal c ortex to the secretion of endogenous ouabain, we measured the content of this steroid in zona glomerulosa and zona fasciculata tissue freshl y excised from bovine adrenals and in the secretion media of primary c ell cultures derived from these zones. The tissue content of endogenou s ouabain was 5.7-fold higher in the zona glomerulosa than in the zona fasciculata. The concentration of endogenous ouabain was 4.1-fold hig her in 24-hour conditioned media from zona glomerulosa than in zona fa sciculata cultures. Angiotensin II and ACTH stimulated the secretion o f endogenous ouabain from zona glomerulosa cultures, but had no effect on zona fasciculata cultures. These findings suggest that endogenous ouabain is primarily synthesized and secreted from the adrenal zona gl omerulosa. (C) 1995 Academic Press, Inc.