Effects of PTH on Intracellular Calcium of MDCK Cells in Culture
| Autor: | V. L. Costa Silva, A.T. Ferreira, F. Zaladek Gil, M.E.M. Oshiro |
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| Rok vydání: | 1997 |
| Předmět: | |
| Zdroj: | Cellular Physiology and Biochemistry. 7:35-42 |
| ISSN: | 1421-9778 1015-8987 |
| Popis: | Intracellular calcium [Ca2+]i exerts multiple functions in renal epithelia and is regulated by several hormonal factors, among them parathyroid hormone (PTH). The effect of PTH on [Ca2+]i was investigated in Madin-Darby canine (MDCK) kidney cells in culture. Changes in [Ca2+]i were monitored fluorometrically with the Ca2+-sensitive probe fura 2/AM, at 37° C. The addition of PTH, in three cumulative doses, led to a significant and sustained raise in [Ca2+]i, in a medium with 1.36 mAf [Ca2+]e. When Ca2+ was subtracted from the extracellular medium, [Ca2+0]e, the addition of PTH caused discrete changes on [Ca2+]i, suggesting that the hormone-induced alteration in [Ca2+]i depend not only on [Ca2+]e, but also on intracellular stores of the ion. Nifedipine (NF) and verapamil (VP) partially blocked the PTH-induced increase in [Ca2+]i, when calcium was present in the medium, suggesting that dihydropyridine sensible-type channels are present in the plasma membrane (PM). PTH showed no effect on [Ca2+]i in MDCK cells previously treated with 2 µM thapsigargine (TP) in [Ca2+O]e conditions but the hormone led to further fluctuations in [Ca2+]i when [Ca2+]e was restored to normal values. VP did not interfere with the sharp increase in [Ca2+]i induced in cells depleted from Ca2+, which were reincubated in a normal Ca2+ medium, showing that calcium-release-activated channels (CRAC) may be also present in PM. Our results support the view that MDCK cells are responsive to PTH, and that both voltage-induced calcium channels (Ca2+-VOC) and CRAC are present in the PM of MDCK cells. |
| Databáze: | OpenAIRE |
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