Incorporation of hydroxyeicosatetraenoic acids into cellular lipids of adrenal glomerulosa cells: inhibition of aldosterone release by 5-HETE.

Metabolites of arachidonic acid appear to be involved in the regulation of aldosterone secretion. Adrenal cells metabolize arachidonic acid to several products including hydroxyeicosatetraenoic acids (HETEs). Since HETEs may be incorporated into the membrane lipids in some cells, we investigated whether HETEs were incorporated into lipids of adrenal glomerulosa cells and tested the influence of incorporation on aldosterone secretion. Cells were incubated with [3H] -arachidonic acid, -5-HETE, -12-HETE, -15-HETE or -LTB4. The cellular lipids were extracted and analyzed by TLC. Arachidonic acid was incorporated into all of the cell lipids with greatest accumulations in phospholipids (22%), cholesterol esters (50%), and triglycerides (21%). Uptake was maximal by 30 min. 5-HETE was incorporated into diglycerides and monoglycerides but not into phospholipids or other neutral lipids. The uptake followed a similar temporal pattern as arachidonic acid. 12-HETE was incorporated to a small extent into phospholipids, predominantly phosphatidylcholine. Neither 15-HETE or LTB4 were associated with cellular lipids. Angiotensin increased the uptake of 5-HETE and arachidonic acid into phosphatidylinositol/phosphatidylserine without altering uptake into the other lipids. When cells were pretreated with 5-HETE and washed to remove the unesterified HETE, basal aldosterone release as well as release stimulated by angiotensin, potassium and ACTH were significantly reduced. 15-HETE, which is not incorporated into cellular lipids, was without effect on aldosterone secretion. These studies indicate that 5-HETE may be incorporated into the cellular lipids of adrenal cells and may modulate steroidogenesis.