ZONATION, PARACRINE FUNCTION AND ALDOSTERONE SECRETION IN THE RAT ADRENAL-CORTEX

Using in situ hybridisation we show that, in the rat adrenal, 11 beta- hydroxylase is confined to the inner zones, whereas aldosterone syntha se is expressed exclusively in the glomerulosa. Immunoblotting methods identify an 18-hydroxydeoxycorticosterone (18-OH-DOG) in IEF gels of solubilised inner adrenocortical zone membrane preparations. This ster oid, which can also be identified by immunocytochemistry, cannot be so lvent extracted from the IEF gels unless the gel slices are first trea ted with trypsin. Preincubation of viable whole glandular tissue with trypsin significantly enhances aldosterone output, and eliminates the trypsin releasable 18-OH-DOG pool in IEF gels. The data suggest that 1 8-OH-DOG is synthesised and sequestered in inner zone cells, in a nove l non-solvent extractable manner, but can be mobilised for utilisation as an aldosterone precursor in the glomerulosa.