Grant-in-Aid for international Scientific Research
|Allocation Type||Single-year Grants|
|Research Institution||Sophia University|
KUMAKURA Konosuke Professor, Faculty of Science and Technology, Sophia Univ., 理工学部, 教授 (70129790)
DUCHEN Micha ロンドン大学生理学教室, Reader
TATHAM Peter Senior Lecturer, Department of Physiology , University College London, Senior Lec
GOMPERTS Bastian D. Professor, Department of Physiology, University College London, 教授
HIDE Izumi Assistant, Hiroshima University School of Medicine, 医学部, 教務員 (20253073)
IMAIZUMI Mica Assistant, Faculty of Science and Technology, Sophia Univ., 理工学部, 助手 (40201941)
INOUE Kazuhide Chief Laboratory, National Institute of Hygenic Science, 薬理部, 室長 (80124379)
TERAKAWA Susumu Professor, University of Hamamatsu School of Medicine, 教授 (50014246)
DUCHEN Michael R. Reader, Department of Physiology, University College London
MILLAR Julli クイーン, メリー&ウェストフィールド大学・生理学教室, Senior Lec
|Project Period (FY)
1994 – 1995
Completed(Fiscal Year 1995)
|Budget Amount *help
¥11,400,000 (Direct Cost : ¥11,400,000)
Fiscal Year 1995 : ¥5,600,000 (Direct Cost : ¥5,600,000)
Fiscal Year 1994 : ¥5,800,000 (Direct Cost : ¥5,800,000)
|Keywords||Regulation of exocytosis / Chromaffin cells / GTP-binding protein / Phospholyration / Video-Microscope / Vesicular movement / Cytoskeleton / Release from Single cells / Amperometric detection|
We have obtained the following results from this research project on the regulation of exocytosis.
1) We have previously demonstrated that myosin lightchain kinase is essential for ATP-dependent priming of exocytosis in adrenal chromaffin cells. By use of mychalolide B,a toxin that selectively inhibit actin-myosin interaction, we demonstrated that actin-myosin interaction is important in ATP-dependent priming mechanism. It was also suggested that ATP-dependent priming is regulated by a trimeric G-protein, Go, and GAP43.
2) In order to understand the dynamics aspects of exocytosis, we analyzed the releasing process by combined use of the carbon fiber DC-amperometry and the video-enhanced contrast DIC microscopy. When a cell was stimulated by acetylcholine or by electrode attachment, current spikes as large as 350 pA appeared and rapid flickers of granule image also appeared simultaneously. About 80% of current spikes were correlated with video microscopic responses, and 20% of spikes were assigned to invisible responses presumably taking place off focus. We conclude that (i) in bovine chromaffin cells, current transients recorded with DC amperometry can be securely considered to represent single vesicular fusion events ; and (ii) that the amplitute distribution is determined primarily by the diffusional profile of the catecholamine.
3) Uridine 5'-triphosphate (UTP)-evoked increase in intracellular Ca^<2+> concentration ([Ca]i) and release of dopamine were investigated using rat pheochromocytoma PC12 cells. The data demonstrated that UTP stimulates P2U-purinoceptors and induces a rise in [Ca]i both by Ca^<2+>-mobilization and Ca^<2+>-influx in PC12 cells. The UTP-evokes dopamine release requires external Ca^<2+> which may enter the cells through pathway sensitive to Zn^<2+>, but insensitive to Cd^<2+> or nicardipine. These results suggested that ATP modulates transmitter release through different types of purinoceptors.