抄録
We asked whether CACNA1C is expressed in parathyroid cells in patients with secondary hyperparathyroidism (SHPTH). Immunohistochemical staining gave positive results for CACNA1C in the parathyroid cells. Parathyroid glands surgically removed from these patients were treated with the digestion buffer to isolate and culture the cells. PTH measurements confirmed secretion of PTH from the cultured cells. Cytoplasmic Ca2+ concentration of the fluo-3 AM loaded cells was measured with a modified Nipkow laser scanning confocal microscope system (CSU-21, Yokogawa Electric Company, Japan) attached to an inverted microscope (Olympus IX70). When the fluo-3 loaded cells were depolarized by exposure to 150 mM K+ solution, a transient increase in fluo-3 fluorescence was detected only in the presence of extracellular Ca2+. The fluo-3 Ca2+ transients were found to be sensitive to Ca2+ channel agonist, FPL64176 and a Ca2+ channel antagonist, nitrendipine. Depolarizing the cells under the whole-cell configuration also evoked inward Ca2+ currents, which showed current-voltage relationship similar to that of L-type Ca2+ channels (peak current around 0 mV). These results suggest that CACNA1C is expressed in parathyorid cells in patients with SHPTH. [Jpn J Physiol 55 Suppl:S207 (2005)]
