Abstract
Summary
The effect of combined di-phenylhydantoin and phenobarbital administration on the response of vitamin D-de-pleted rats to ergocalciferol, cholecalciferol, and 25-hydroxycholecalciferol (25-OHCC) was measured by determinations of serum calcium and phosphate concentrations and of intestinal transport of calcium in vitroby everted loops of small intestine. The major action of this anticonvulsant drug treatment in the rat was to inhibit the action of the various forms of vitamin D including 25-OHCC in increasing active transport of calcium by the everted intestine. The increase of calcium diffusibility across the intestine by vitamin D was not blocked nor was the action of vitamin D in increasing serum calcium concentrations. A specific inhibitory effect of the anticonvulsant drugs on an energy-dependent calcium transport system in the intestinal mucosa is suggested.
This work was supported by USPHS Grant AM-00668. 25-hydroxy-cholecalciferol was supplied to us by Dr. John Babcock, the Upjohn Company. We thank Mrs. Evelyn Bull for important technical assistance.
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