The effects of arginine vasopressin (AVP) and its nonpressor analogue desamino-8-arginine vasopressin (dDAVP) on immunoreactive prostaglandin E and thromboxane B2 synthesis from endogenous arachidonic acid by epithelial cells isolated from toad urinary bladders were investigated. In epithelial cell suspensions prepared using a collagenase treatment, AVP (5 mU/ml) stimulated prostaglandin E synthesis from 0.27 +/- 0.05 to 0.53 +/- 0.09 pmol . min-1 . mg protein-1 (P less than 0.01, n = 6) and stimulated thromboxane A2 synthesis, as assessed by measurement of its stable metabolite thromboxane B2, from 0.032 +/- 0.004 to 0.054 +/- 0.009 pmol . min-1 . mg protein-1 (P less than 0.02, n = 6). dDAVP (130 nM) also stimulated immunoreactive prostaglandin E and thromboxane B2 synthesis (P less than 0.05, n = 6). In cells prepared by EDTA treatment or scraping, aVP did not alter prostaglandin or thromboxane synthesis. This study demonstrates that AVP and dDAVP stimulate both prostaglandin and thromboxane synthesis in epithelial cells from the toad urinary bladder and suggests that the antidiuretic activity of these peptides is associated with this effect. The results are consistent with previous observations that the synthesis of prostaglandin E and thromboxane by epithelial cells results in a negative and positive modulation, respectively, of the action of AVP on water transport.