Barium bioavailability as the chloride, sulfate, or carbonate salt in the rat

This study was conducted to determine how the bioavailability of a low concentration of barium (Ba) in drinking water is affected by the anion. Male Sprague Dawley rats weighing 250-300 grams were maintained on a diet of less than 1 mg Ba/kg of food for at least 1 month prior to experimentation. Rats were given 10.0 mg 131Ba/liter as sulfate (SO4), chloride (Cl), or carbonate (CO3) at pH 7.0. Animals were sacrificed at 2, 5, 10, 20, 30, 60, and 120 minutes and 24 hours after intubation. When 131Ba was administered, as Cl, 131Ba in blood rose linearly for 10 minutes and then less rapidly until the highest number of counts was measured at 60 minutes. At 24 hours 131Ba was still at 90% of peak levels. Five tissues were tested 24 hours after dosing for 131Ba. In decreasing order of 131Ba concentration they were heart, eye, skeletal muscle, kidney, and liver. 131Ba in the heart reached 8x that observed in blood 24 hours after dosing. In the eye, 131Ba increased linearly for 1 hour. Isotope concentrations in the eye eventually reached 2.5x that observed in blood. When 131Ba was administered as SO4 or CO3, 131Ba in blood was respectively 85% or 45% of levels, of 131Ba from 131BaCl2. Initial uptake of 131Ba and deposition in the eye were not different when administered as Cl or SO4.