A characterisation of cyclic AMP release from monolayer cultures of normal human thyroid cells
Bidey, S.P.; Marshall, N.J.; Ekins, R.P.
Acta Endocrinologica 101(3): 359-364
1982
ISSN/ISBN: 0001-5598 PMID: 6293232 Document Number: 188228
The TSH-dependent and time-related release of cAMP was characterized in primary monolayer cultures of normal human thyroid cells. Accumulation of cAMP within the incubation medium was detectable within 1 h of exposure of cultures to 5 mU TSH/ml, and increased throughout of subsequent 15 h incubation period, final levels attained being consistently in excess of the corresponding intracellular cAMP levels. Accumulation of cAMP in the incubation medium was dependent on TSH dose, for both short (1 h) and prolonged (16 h) incubations. Moreover, after incubation for 16 h, cAMP levels in the incubation medium were significantly (P < 0.01) in excess of intracellular levels for each dose of TSH tested above 0.2 mU/ml. In the absence of TSH, accumulation of cAMP in the incubation medium remained low, after both 1 h and 16 h incubation periods. A consideration of these observations suggests that a bioassay based upon the cAMP content of incubation medium samples should provide a more precise detection system for thyroid stimulators than those measuring the intracellular cAMP response, and this was demonstrated for a cell preparation in which the intracellular response to TSH was minimal.