Effect of TSH on Iodine Metabolism and Intermediary Metabolism in Tissue from Patients with Graves' Disease

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Abstract
The present studies examined in vitro the TSH responsiveness of thyroid tissue from 17 patients with treated Graves' disease and 1 untreated patient. Basal adenylate cyclase, cyclic AMP concentrations, l-14C-glucose oxidation and 32P incorporation was similar in normal thyroid and tissue from patients with Graves' disease. TSH increased adenylate cyclase activity and 32P incorporation into phospholipids to the same extent in both types of thyroid tissue. In contrast, stimulation of glucose oxidation and cyclic AMP concentrations was significantly less in thyroid from patients with Graves' disease. Basal incorporation of 131I into monoiodotryosine and diiodotyrosin was diminished in thyroid slices from patients with Graves' disease but the percent increase was significantly greater than in normal thyroid tissue. This might reflect the reduced base line values in Graves' disease, since the absolute increments in iodoamino acid synthesis induced by TSH were as great in Graves' disease as in normal thyroid tissue. The mean thyroid/medium ratio for 131I was similar in both types of thyroid but there was much greater variation among the patients with Graves' disease. Phosphodiesterase activity was similar in both types of thyroid tissue and enzyme activities with two Km's for cyclic AMP demonstrated. Although the interpretation of the results in patients with treated Graves' disease might be clouded because of the antithyroid medications which they had received, the data is most consistent with the conclusion that the thyroid tissue from patients with Graves' disease responds normally to TSH.

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