COMPARISON OF EFFECT OF TSH AND FLUORIDE ON ADENYLATE-CYCLASE ACTIVITY OF COLD THYROID NODULES

  • 1 January 1976
    • journal article
    • research article
    • Vol. 37  (2) , 107-108
Abstract
Using a simple and reliable assay technique in which the actual amount of cyclic AMP generated during incubation is determined by competitive protein binding assay, adenylate cyclase activity was measured in 7 cold nodules and 3 samples of normal [human] thyroid tissue. Mitochondrial fraction prepared from surgically obtained tissues was used as the source of the enzyme. An increased adenylate cyclase activity in cold nodules was observed compared to normal. This activity was much more responsive to TSH [thyrotropin] in cold nodules than in normal (maximal stimulation: 1050 .+-. 200% vs. 320 .+-. 120%). Maximal TSH stimulation was similar to that elucited by fluoride in the cold nodules but only 1/3 in normal tissue. Higher efficiency of TSH in cold nodules may be related to increased TSH binding or coupling of TSH receptors with the catalytic subunit of adenylate cyclase.

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