Experiments were undertaken in two groups of barbiturate anaesthetized dogs to examine whether atrial natriuretic factor (ANF) exerts an effect on renal release of prostaglandin E2 (PGE2). In the first group, intravenous infusion of ANF (50 ng min-1 kg-1 body wt) reduced basal PGE2 release from 4.4 +/- 0.8 pmol min-1 to 1.8 +/- 0.7 pmol min-1. In the second group, intrarenal infusion of an alpha 1-adrenoceptor agonist, phenylephrine (2.5-6.75 micrograms min-1), raised PGE2 release from 2.7 +/- 0.5 pmol min-1 to 7.5 +/- 1.3 pmol min-1. During continuous alpha 1-adrenergic stimulation, intravenous infusion of ANF (100 ng min-1 kg-1 body wt) reduced PGE2 release to 3.5 +/- 1.0 pmol min-1. These results demonstrate that ANF reduces basal and alpha 1-adrenergic stimulated renal PGE2 release.