Mechanism of action of the calcium-sensing receptor in human antral gastrin cells
Mechanism of action of the calcium-sensing receptor in human antral gastrin cells
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DOI：
10.1053/gast.2001.23246
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发表时间：
2001-04-01
期刊：
影响因子：
29.4
通讯作者：
Meloche, RM
中科院分区：
文献类型：
--
作者：
Buchan, AMJ;Squires, PE;Meloche, RM
Background & Aims: Human G cells express the calcium-sensing receptor and respond to extracellular calcium by releasing gastrin. However, the receptor on G cells is insensitive to serum calcium levels. We investigated whether this is a result of differential regulation of signaling pathways compared with parathyroid or calcitonin cells. Methods: Gastrin release from primary cultures of human antral epithelial cells enriched for G cells (35%) was measured by radioimmunoassay. G cells were stimulated by increasing extracellular calcium concentration for 1 hour in the presence or absence of antagonists of specific intracellular signaling pathways. Intracellular calcium levels were monitored to evaluate the effect of the antagonists on calcium influx, Results: Inhibition of phospholipase C decreased calcium-stimulated gastrin release, but blockers of adenylate cyclase, phospholipase A(2), or mitogen-activated protein kinase had no effect, Inhibition of protein kinase C, nonselective cation channels, and phosphodiesterase increased basal and calcium-stimulated gastrin release while decreasing calcium influx. These data were consistent with basally active phosphodiesterase. Conclusions: The calcium-sensing receptor on the G cell activates phospholipase C and opens nonselective cation channels, resulting in an influx of extracellular calcium. Protein kinase C isozymes expressed by the G cells play multiple roles regulating both gastrin secretion and phosphodiesterase activity.
