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

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.