The Journal of Nutrition Vol. 127 No. 3 March 1997, pp. 478-482
Copyright ©1997 by the American Society for Nutritional Sciences

Absorption, Retention and Urinary Excretion of Chromium-51 in Rats Pretreated with Indomethacin and Dosed with Dimethylprostaglandin E₂, Misoprostol or Prostacyclin

Manuscript received 11 March 1996. Initial reviews completed 21 May 1996. Revision accepted 9 September 1996.

Department of Nutritional Sciences, and ^* Department of Physiological Sciences, Oklahoma State University, Stillwater, OK 74078-6141

Drug-nutrient interactions affecting chromium were investigated in this study. Rats were injected with indomethacin to reduce endogenous prostaglandin synthesis and dosed with prostaglandin analogues or prostacyclin. Effects on absorption, tissue distribution and urinary excretion of ⁵¹Cr from ⁵¹CrCl₃ were evaluated using a 2 × 4 factorial experimental design. Forty-eight adult male rats were food deprived for 12 h and then injected intraperitoneally with indomethacin (5 mg/kg body wt) or placebo. Thirty minutes later, rats were intubated and dosed with one of four treatments: a prostaglandin E₁ analogue (misoprostol) at 50 µg/kg body wt; a prostaglandin E₂ analogue (16,16-dimethylprostaglandin E₂) at 7.5 µg/kg body wt; prostacyclin at 20 µg/kg body wt; or control (7.64 mmol/L Tween-80 suspended in 0.15 mol/L NaCl containing 0.48 mol/L ethanol). Immediately after intubation, rats were dosed with 3.7 mBq of ⁵¹CrCl₃ by micropipette. Blood was collected from the tail at intervals after ⁵¹Cr dosing. Six hours after dosing, ⁵¹Cr rats were exsanguinated by cardiac puncture. Indomethacin, an inhibitor of prostaglandin synthesis, significantly increased (P < 0.05) ⁵¹Cr in blood at all time periods tested except at 15 min. In tissues, indomethacin significantly increased ⁵¹Cr retention. Urinary ⁵¹Cr excretion at 6 h was higher (P < 0.05) in indomethacin-pretreated rats than in control rats. Administration of indomethacin, which blocks prostaglandin synthesis, enhanced ⁵¹Cr absorption, whereas dosing with 16,16-dimethylprostaglandin E₂ decreased ⁵¹Cr absorption.