Mechanism underlying the spontaneous changes in the cytosolic CaィイD12+ィエD1concentrations in rat adrenal chromaffin cells

1999 Fiscal Year Final Research Report Summary

• Project/Area Number: 10670045
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: General physiology
• Research Institution: Kagoshima University
• Principal Investigator: SORIMACHI Masaru Kagoshima University, Faculty of Medicine, Professor, 医学部, 教授 (70036440)
• Co-Investigator(Kenkyū-buntansha): KAMEYAMA Masaki Kagoshima University, Faculty of Medicine, Professor, 医学部, 教授 (60150059) ; YAMAGAMI Kazuhiko Kagoshima University, Faculty of Medicine, Research Associate, 医学部, 助手 (30041354)
• Project Period (FY): 1998 – 1999
• Keywords: Mouse adrenal medulla / the cytosolic CaィイD12+ィエD1concentration / confocal microscope / Oregon-green-BAPTA-1 / ATP / gap-junction / lucifer yellow / Rhodamine green dextran / ロダミン-グリーン-デキストラン

Research Abstract

The spontaneous fluctuations of the cytosolic CaィイD12+ィエD1 concentrations ([Ca]ィイD2inィエD2) have often been observed in isolated single rat adrenal chromaffin cells. To see whether these [Ca]ィイD2inィエD2 changes occur also in vivo, we measured [Ca]ィイD2inィエD2 in individual chromaffin cells involved in adrenal slice preparations after loading with Oregon-green-BAPTA-1/AM. We often observed the spontaneous changes in [Ca]ィイD2inィエD2 when measured with cofocal laser-scanning microscope. In addition, we found that the spontaneous [Ca]ィイD2inィエD2 increase immediately spreads to the neighboring cells in some cases. The synchronization of [Ca]ィイD2inィエD2 increases among the neighboring cells occurs more frequently in mouse adrenal medullary slice preparations, where the gap-junction has been shown to exist. Treatment of mouse adrenal slices with the ATP receptor antagonist PPADS did not inhibit the spread of CaィイD12+ィエD1 signals, and ATP increased [Ca]ィイD2inィエD2 in only 30% of isolated cells tested, suggesting that ATP released from the cells is not responsible for the excitation of the neighboring cells. We also investigated the effects of the inhibitors of gap-junctions on the spread of CaィイD12+ィエD1 signals, but these agents markedly inhibited the occurrence of the spontaneous [Ca]ィイD2inィエD2 increase. However, the combined loading of Lucifer yellow and Rhodamine green dextran-70000 into the cells through the damaged membrane revealed that the distribution pattern of the former agent, which passes through the gap-junctions, was broader than that of the latter. These results suggest that the synchronized [Ca]ィイD2inィエD2 changes among cells were mediated by the gap junctions between the cells.