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Paracrine interactions among parathyroid cells: Effect of cell density on cell secretion
Author(s) -
Sun Feng,
Maercklein Peter,
Fitzpatrick Lorraine A.
Publication year - 1994
Publication title -
journal of bone and mineral research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.882
H-Index - 241
eISSN - 1523-4681
pISSN - 0884-0431
DOI - 10.1002/jbmr.5650090703
Subject(s) - parathyroid chief cell , parathyroid hormone , secretion , endocrinology , medicine , paracrine signalling , cell , chemistry , immunocytochemistry , cell culture , calcium , biology , receptor , biochemistry , genetics
Cell‐cell interactions are important in the regulation of endocrine cell secretion. To investigate the possibility that cell communication may alter the regulation of parathyroid cell secretion, we utilized the reverse hemolytic plaque assay (RHPA) to measure parathyroid hormone (PTH) release from individual cells. Bovine parathyroid cells were dispersed and plated with protein A‐conjugated erythrocytes at cell densities ranging from 0.9 to 36 X 10 2 cells/cm 2 in 0.2 mM calcium. Cell populations were greater than 98% homogeneous as determined by immunocytochemistry and in situ hybridization for PTH mRNA. Plaques were developed and data analyzed for the amount of PTH per cell released (plaque area in μm 2 X 10 4 ) and the determination of cell recruitment (% plaques formed). A positive correlation existed between parathyroid cell density and the amount of PTH released. As the distance between cells increased, the plaque area (amount of PTH released per cell) decreased (ranging from 1.0 X 104 4 μm 2 at 0.9 X 10 2 cells/cm 2 versus 1.6 X 10 4 μm 2 at 36 X 10 2 cells/cm 2 ). The percentage of cells releasing PTH (recruitment) also decreased (16% at 0.9 X 10 2 cells/cm 2 versus 47% at 36 X 10 2 cells/cm 2 ). These data suggest that parathyroid cells in close proximity are stimulated to secrete more hormone than those at lesser densities. In addition, parathyroid cells are recruited to secrete PTH when plated at high density. Factor(s) released by the parathyroid cell may increase cell responsiveness and stimulate secretion in a paracrine fashion.