Abstract
1 Anti-inflammatory steroids reduce prostaglandin E2 (PGE2) synthesis in rat renomedullary interstitial cells in culture by inhibiting the release of arachidonic acid from membranous phospholipid stores, exhibiting antiphospholipase-like properties. 2 After treatment of the cells with dexamethasone 10(-6)M, these cells release a protein in the supernatant. 3 This supernatant is able to inhibit PGE2 secretion in untreated cells and to inhibit phospholipase A2 activity in an in vitro system. 4 Using chromatofocusing separation, we showed that two distinct proteins exist with isoelectric points of 5.8 and 8.3. 5 Using gel permeation separation, we showed that two proteins exist with apparent molecular weights of 15,000 and 30,000 daltons. 6 We conclude that, in renal cells in culture, anti-inflammatory steroids induce the synthesis and the release of two polypeptides which we have named 'Renocortins' (induced by corticoids in renal cells) causing the antiphospholipase-like action of glucocorticoids. 7 Our results are in good agreement with others, but as renal cells are not directly involved in the inflammatory process, we suggest that this steroid-induced phenomenon is not solely involved in the inflammatory reaction but is of more general physiological relevance.