We studied insulin's effects on glucose production (Ra) and utilization (Rd) in trained, conscious dogs before and during treatment with indomethacin (Indo) and salicylate (S). Ra and Rd (mg X kg-1 X min-1) were calculated by isotope dilution using [3-3H]glucose. Animals were treated with either oral Indo or acetylsalicylic acid for 1 day before the respective studies. On the study day, experimental animals were given a continuous infusion of either saline (control), Indo (5 mg/kg bolus followed by 0.05 mg X kg-1 X min-1), or sodium salicylate (0.45 mg X kg-1 X min-1) for 330 min on separate days; each animal participated in all three protocols. After establishing steady-state specific activity, control (C) and experimental animals (n = 6/group) received insulin, 0.275 mU X kg-1 X min-1 for 150 min, raising serum insulin levels two- to threefold above basal. During insulin infusion in C, plasma glucose (G) fell from 99 +/- 2 to 82 +/- 6 ml/dl (P less than 0.01), associated with a transient fall in Ra from 2.5 +/- 0.3 to 1.9 +/- 0.2 (P less than 0.01) at 30 min, returning to base line at 45 min; Rd did not change. In the Indo and S groups, G also fell by a similar extent. In contrast to C, however, the fall in G was associated with a rise in Rd, commencing at 30 min in the Indo group (P less than 0.05) and at 45 min in the S group (P less than 0.01); Ra did not fall and actually rose above basal (P less than 0.05), although it did not match the rise in Rd.(ABSTRACT TRUNCATED AT 250 WORDS)