Individual parathyroid cells are more sensitive to calcium than a parathyroid cell population.
Information on the secretory behavior of individual parathyroid cells within a cell population has not previously been available. We now report a technique for examining quantitative changes in hormone secretion in individual parathyroid cells. We have used a reverse hemolytic plaque assay to measure cumulative PTH release in single isolated cells. Bovine parathyroid cells were dispersed with trypsin and mixed with staphylococcal protein-A-linked ovine erythrocytes. Cells were plated in a monolayer in the presence of PTH antiserum. After stimulation by an agonist, complement was added to the cells. Lysis of ovine erythrocytes formed a plaque around each individual cell that releases PTH. Results indicate that inhibition of PTH release by calcium was not affected by trypsinization. Plaque formation was dependent on all reagents; serial dilution of antiserum reduces plaque formation. Cells had a markedly uniform secretory response to calcium. We compared PTH release in individual cells measured by the reverse hemolytic plaque assay with hormone release in a parathyroid cell population measured by RIA. There was an inverse relationship between extracellular calcium concentrations and plaque area. Individual cells were more sensitive to calcium (ED50 = 0.4 mM Ca2+) than cell populations (ED50 = 0.8 mM Ca2+). We demonstrate that PTH release can be quantitated in single viable parathyroid cells.
Fitzpatrick
L A
LA
Department of Medicine, University of Texas Health Science Center, San Antonio 78284.
Leong
D A
DA
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002469:Cell Separation; D006462:Hemolytic Plaque Technique / Q000592:standards; D009994:Osmolar Concentration; D010280:Parathyroid Glands / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010281:Parathyroid Hormone / Q000378:metabolism; D011863:Radioimmunoassay; D012680:Sensitivity and Specificity; D014357:Trypsin / Q000494:pharmacology
D010281:Parathyroid Hormone; D014357:Trypsin; D002118:Calcium