The Role of Na(superscript +)/Ca(superscript 2+) Exchanger in Modulating Calcium Homeostasis in Bovine Chromaffin Cell

鈉鈣交換蛋白對牛嗜鉻細胞鈣離子恆定之調控

黃昭華(Chou-Hua Huang) ； 李佳學(Chia-Hsueh Lee) ； 潘建源(Chien-Yuan Pan)

《Acta Zoologica Taiwanica》 14卷2期 (2004/10) Pp. 135-136

https://doi.org/10.6576/AZT.2004.14.(2).23

摘要

嗜鉻細胞受到乙醯膽鹼刺激時，造成鈉離子湧入，並開啓電位閘門通道。自電位閘門通道湧入的鈣離子，會引發CICR，造成細胞內鈣離子濃度大量上升，促進胞吐作用的進行。同時，自乙醯膽鹼受器湧入的鈉離子，會讓鈉鈣交換蛋白短暫地反轉，貢獻一部份的鈣離子湧入。我們發現用Thapsigargin排空內質網會降低鈉鈣交換蛋白反轉所引起的[Ca(上標 2+)]c上升。此外，處理Ryanodine受器抑制劑Ryanodine或IP3受器抑制劑2-APB也皆能減少[Ca(上標 2+)]c之上升量。若同時處理Ryanodine及2-APB，其結果與單獨處理2-APB無顯著差異。這些結果表示鈉鈣交換蛋白反轉的確能夠使內質網從Ryanodine受器與IP3受器釋放鈣離子，且IP3受器可能扮演調控Ryanodine受器開啓的角色。鈉鈣交換蛋白和Ryanodine受器、IP3受器之間的互動對細胞內鈣離子恆定有重要影響。

關鍵字

嗜鉻細胞 ； 乙醯膽鹼 ； 電位閘門 ； Ryanodine受器 ； 鈣離子

並列摘要

Bovine chromaffin cells can be stimulated by acetylcholine to allow Na(superscript +) influx and the opening of voltage-gated Ca(superscript 2+) channels (VGCC). Ca2+ entry via VGCC dramatically increases [Ca(superscript 2+)]c by the process of Ca(superscript 2+)-induced Ca(superscript 2+) release (CICR) and the increase in [Ca(superscript 2+)]c promotes exocytosis. At the same time, Na(superscript +) influx through acetylcholine receptor temporarily induces the reverse mode activity of Na(superscript +)/Ca(superscript 2+) exchanger (NCX), which also contributes to part of Ca(superscript 2+) influx. It is controversial whether the reverse mode of NCX also can promote CICR. Here our results show that the elevation of [Ca(superscript 2+)]c by the reverse mode of NCX was inhibited by emptying ER with Thapsigargin. Besides, [Ca(superscript 2+)]c rising could be inhibited by the treatment of either Ryanodine (Ry), a Ryanodine receptor (RyR) inhibitor or 2-APB, an IP3 receptor (IP3R) inhibitor. The effect of treating 2-APB and Ry simultaneously had no significant difference from that of treating 2-APB alone. We concluded that the reverse mode of NCX can promote the release of Ca(superscript 2+) from ER through RyR and IP3 receptor (IP3R). Furthermore, IP3R may function as a modulator of the opening of RyR. The crosstalk of NCX, RyR, and IP3R has important effects on intracellular calcium homeostasis.

並列關鍵字

chromaffin cells ； acetylcholine ； voltage-gate ； Ryanodine receptor RyR ； calcium ion