COMPARISON OF THYROIDAL AND GASTRIC IODIDE PUMPS IN RATS1

Abstract

Low iodine intake activated the thyroidal iodide pump of rats but had no effect on the gastric pump. Thyroid/serum (T/S) and gastric juice/serum (J/S) radioiodide concentration ratios were similar in rats receiving adequate amounts of dietary iodine. When graded doses of NaI127 or NaClO4 were injected, the T/S was more markedly depressed at any dose level used than was the J/S. In rats on a diet with adequate iodine content the capacity of the rat''s stomach juice for "pumped" iodide was found to be higher than that of the thyroid. Analysis of the findings suggests that the gastric iodide pump differs from its thyroidal counterpart a) by not being responsive to TSH and to low serum iodide levels, and b) by having a smaller affinity for iodide.