DIFFERENCES IN PTH(1-84) RELEASE IN RESPONSE TO AMBIENT CALCIUM CONCENTRATIONS OF PARATHYROID ADENOMA FRAGMENTS AND DISPERSED PARATHYROID ADENOMA CELLS IN CULTURE

In a previous study we observed that during perfusion of normal human parathyroid tissue, the release of PTH (1-84) was modulated by ambient extracellular calcium (Ca++) and lithium (Li+) concentrations in the media and preliminary studies indicated that this stimulus-response co upling was absent in human parathyroid adenoma fragments, The present study compares the responsiveness of parathyroid adenoma fragments and isolated parathyroid adenoma cells from the same adenoma and their re sponse to Ca++ changes and Li+ presence in culture media, The data ind icate that parathyroid adenoma tissue fragments fail to respond to amb ient changes in Ca++ and Li+, In contrast, dispersed parathyroid cells preparations responded with a significant increase of PTH (1-84) rele ase (50%) under the influence of low ambient calcium concentrations, S ix of the dispersed cell preparations also responded with a 45% decrea se in PTH release under the influence of a high Ca concentration in th e medium, Isolated parathyroid cells obtained from the same adenoma's did not respond to the presence of Li++ in the medium, These data sugg est that human parathyroid adenoma tissue functions autonomously and i s not sensitive to calcium regulation in the tissue configuration as o pposed to the isolated cell suspensions, The nature of this difference remains elusive.