In order to investigate the effects of prostaglandin E1 (PGE1) used in hypotensive anesthesia on the adrenal endocrine function, aldosterone, corticosterone (Comp B) and cAMP production were measured in isolated glomerulosa (G-c) and fasciculata cells (F-c) of the rats. Rat glomerulosa and fasciculata cells were obtained by enzymatic digestion of the adrenals of male wistar rats. The cell pellet was suspended in Hank's balanced salt solution containing 0.1% BSA and distributed in 900 microliters aliquots to polyethylene tubes. The samples were preincubated for 90 min in a 37 degrees C water bath aerated with 5% CO2/95% O2. PGE1 or ACTH 50 microliters was added and incubated for 4 hr. Total volume of the incubation medium is 1.0 ml. Aldosterone and cAMP were measured by radioimmunoassay and Comp B was determined by fluorimetric method. PGE1 increased significantly the basal secretion of aldosterone and Comp B in G-c and F-c, respectively. The steroidogenic effect of PGE1 was dose dependent in aldosterone production. This aldosterone production was also accompanied with cAMP production. On the other hand, significant increase of cAMP was not observed in comp B production. These results suggest that cAMP may be the second messenger in PGE1-induced aldosterone production in G-c. But PGE1 receptors in F-c seem not to be coupled to the adenylate cyclase system. The addition of ACTH and PGE1 resulted in inhibition of aldosterone secretion when compared with that obtained by ACTH alone. Several researchers have shown that low doses of PGE1 depressed the basal aldosterone secretion. These findings may be contributing to Na-uresis effect during PGE1-induced hypotension.