ADENYL CYCLASE ACTIVITY IN HUMAN THYROID PLASMA MEMBRANES FROM NORMAL HUMAN THYROID TISSUE AND THYROID ADENOMAS

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Abstract
The adenylatecyclase (AC) activity of crude human thyroid plasma membranes were studied in some detail and conditions for optimal cyclic[c]AMP-production established. Membranes from 8 cold and 2 hot thyroid adenomas were investigated and compared to membranes from corresponding normal, paranodular tissues. The investigated membranes contained similar basal AC activities, which were stimulated 3-5 times with TSH [thyrotropin] and 20-30 times with F-. No difference in the TSH-sensitivity of AC from normal and cold adenomas could be detected. TSH 0.02 mU[units]/ml caused a measurable and 0.15 mU/ml a half-maximal stimulation of the cAMP-production. Disturbances of thyroid hormone production characteristic of thyroid adenomas are not caused by alterations of the TSH-AC system. In a thyroid cell the degree of thyroid hormone synthesis does not alter the amount of plasma membrane-bound AC.