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Roles of intracellular calcium and monomeric G-proteins in regulating exocytosis of human neutrophils

Zhu Ying, Wang Junhan, Wu Jianmin, Xu Tao, Zhang Chunguang

Institute of Biophysics and Biochemistry,School of Life Science and Technology,Huazhong University of Science and Technology.Wuhan 430074,Hubei；China；Union Hospital,Huazhong University of Science and Technology.Wuhan 430030,Hubei

Abstract

The results showed that the membrane capacitance increase induced by calcium revealed a biphasic process. The first phase occured when the calcium level was between 0.2-14 #mu#mol/L with a plateau amplitude of 1.23 pF and a calcium EC50 of 1.1 #mu#mol/L. This phase might correspond to the release of the tertiary granules. The second phase occured when the calcium concentration was between 20-70 #mu#mol/L with a plateau increment of 6.36 pF, the calcium EC50 being about 33 #mu#mol/L. This phase might represent the release of the primary and secondary granules. Intracellular calcium also simultaneously increased the exocytotic rate and the eventual extent in neutrophils. On the other hand, GTP#gamma#S can increase the exocytotic rate in a dose-dependent manner but had no effect on the eventual extent of membrane capacitance increment (>6 pF) if the cell was stimulated for a long period (>20 min). GTP#gamma#S (ranging from 20 to 100 #mu#mol/L) induced the neutrophils to release all four types of the granules at very low intracellular calcium level.

Key words: Neutrophils;Exocytosis;Calcium;Monomeric

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Citing This Article：

Zhu Ying, Wang Junhan, Wu Jianmin, Xu Tao, Zhang Chunguang. Roles of intracellular calcium and monomeric G-proteins in regulating exocytosis of human neutrophils. Acta Physiol Sin 2003; 55 (6): (in Chinese with English abstract).