Effect of Nigericin on Glucose Transport in 3T3-L1 Adipocytes
| Autor: | Chih-ying Chu, 朱芝瑩 |
|---|---|
| Rok vydání: | 2000 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 88 Pretreatment of Nigeicin, a K+/H+ ionophore and well known for intracellular acidification, induced an increase in basal but inhibition in insulin-stimulated 2-Deoxy-D-glucose transport by a dose- and time-dependent manner in 3T3-L1 adipocytes. Using a pH-sensitive fluorescent dye, BCECF, acidid pHi has been induced by adding Nigericin in cells. Subcellular fractionation and immunoblotting analysis indicated the content of GLUT1 in plasma membrane was increased whereas insulin-induced translocation of GLUT4 was greatly eliminated by Nigericin pretreatment of cells. The total cellular amount of GLUT1 or GLUT4, on the other hand, was not altered. Thus theses results seem to suggest that Nigericin has opposite effect on basal and insulin-stimulated glucose transport by lowering pHi. However, lowering pHi by exogenous HCl had no effect on 2-DG uptake. Ouabain, on the other hand, potentiated the effect of Nigericin on 2-DG uptake These results imply that lowering [K+]i but not acidic pHi may be responsible for Nigericin’s effect on glucose transport. Furthermore, Insulin-stimulated PI 3-kinase activity was not altered and 2-DG uptake stimulated by insulin, insulin mimetics and PMA were all inhibited, indicating that Nigericin pretreatment may affect a common process involved in redistribution (translocation) of the vesicle containing GLUTs. In addition, the effect on basal glucose transport was abolished whereas on insulin-stimulated glucose uptake was not altered by removal of Nigericin. Putting all together, we conclude that the effect of Nigericin on glucose transport may be caused by [K+]i but not pHi lowering, and its effect on basal and insulin-stimulated glucose transport may involve two distinct mechanisms. 審定證明書 授權書 誌 縮寫表 中文摘要 …………………………………… 1 英文摘要 …………………………………… 3 緒 論 …………………………………… 4 材 料 …………………………………… 9 方 法 ……………………………………13 結 果 ……………………………………31 討 論 ……………………………………40 圖 表 ……………………………………44 參考文獻 ……………………………………60 |
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