Inhibition of cell growth retains differentiated function of bovine parathyroid cells in monolayer culture.

Monolayer culture of bovine parathyroid cells for up to 4 days in medium containing 10% serum resulted in cell hypertrophy and proliferation as well as functional dedifferentiation. Compared to freshly isolated cells there was a right-shifted dose-effect relationship for calcium-inhibited parathyroid hormone (PTH) release, a decreased suppressibility of secretion and an inability of the cytoplasmic Ca2+ concentration (Ca2+i) to follow changes in the extracellular Ca2+ concentration. The functional changes seemed not to be due to culture per se, since human parathyroid cells exhibited an essentially unchanged regulation of Ca2+i even after 8 days of culture in 10% serum. During culture in medium containing 0.1% serum, the bovine cells did not proliferate and there was only slight cell hypertrophy. These cells retained much of their ability to regulate Ca2+i and PTH release. The results indicate that functional dedifferentiation of parathyroid cells is related to cell growth.