Figure 4.

Effects of stepwise increases in Ca²⁺_o concentration on cytoplasmic free Ca²⁺ concentration from normal and adenomatous parathyroid cells in the absence of amino acids. Collagenase digested cells were loaded with fura-2 and perifused with physiological saline solutions containing various Ca²⁺_o concentrations (in mM), and calibrated microfluorimetry data were collected for single cells as described in Materials and Methods. The data are presented as time-averaged traces for 40 normal parathyroid cells obtained in four experiments (four subjects who underwent thyroid surgery) and 50 adenomatous parathyroid cells obtained in five experiments (five subjects with primary hyperparathyroidism who underwent parathyroidectomy for adenomatous disease). Ca²⁺_o was 0.2 mM at the start and end of these experiments.