Time course of gastrointestinal tract permeability to chromium 51-labeled ethylenediaminetetraacetate in healthy dogs

Objectives - To establish values for gastrointestinal tract permeation by chromium 51-labeled ethylenediaminetetraacetate (⁵¹Cr-labeled EDTA) in healthy adult dogs, and to evaluate the time course for ⁵¹Cr-labeled EDTA absorption over a 24-hour period after its administration, in an effort to define a shorter, more practical collection method. Animals - 6 healthy adult mixed-breed dogs. Procedure - After an 18-hour nonfeeding period, each dog was given a solution containing 50 μCi of ⁵¹Cr-labeled EDTA in deionized water (10 ml/kg of body weight) by stomach tube. Complete urine collection was done at 2, 4, 6, and 24 hours after ⁵¹Cr-labeled EDTA administration. Five-milliliter samples of urine were counted for 15 minutes in a gamma counter, and radioactivity in urine was expressed as a percentage of the orally administered dose. Results - Median (range) 24-hour urinary recovery of ⁵¹Cr-labeled EDTA after 24 hours was 15.1 (12.7 to 20.3)%. Urine collected at 2, 4, and 6 hours contained 1.0 (0.2 to 3.5)%, 6.5 (2.2 to 8.7)%, and 10.0 (8.1 to 11.7)% of the administered ⁵¹Cr-labeled EDTA, respectively. Urine passed during the first 6 hours contained, on average, 67 (54 to 77)% of the total 24-hour urine recovery. Conclusions - 6-hour urinary recovery of ⁵¹Cr-EDTA provides a potential alternative to 24-hour recovery. This shorter collection period may more specifically reflect small intestinal permeability.