In:
American Journal of Physiology-Cell Physiology, American Physiological Society, Vol. 285, No. 5 ( 2003-11), p. C1142-C1149
Abstract:
AlF 4 - is known to generate oscillations in intracellular Ca 2+ concentration ([Ca 2+ ] i ) by activating G proteins in many cell types. However, in rat pancreatic acinar cells, AlF 4 - -evoked [Ca 2+ ] i oscillations were reported to be dependent on extracellular Ca 2+ , which contrasts with the [Ca 2+ ] i oscillations induced by cholecystokinin (CCK). Therefore, we investigated the mechanisms by which AlF 4 - generates extracellular Ca 2+ -dependent [Ca 2+ ] i oscillations in rat pancreatic acinar cells. AlF 4 - -induced [Ca 2+ ] i oscillations were stopped rapidly by the removal of extracellular Ca 2+ and were abolished on the addition of 20 mM caffeine and 2 μM thapsigargin, indicating that Ca 2+ influx plays a crucial role in maintenance of the oscillations and that an inositol 1,4,5-trisphosphate-sensitive Ca 2+ store is also required. The amount of Ca 2+ in the intracellular Ca 2+ store was decreased as the AlF 4 - -induced [Ca 2+ ] i oscillations continued. Measurement of 45 Ca 2+ influx into isolated microsomes revealed that AlF 4 - directly inhibited sarco/endoplasmic reticulum Ca 2+ -ATPase (SERCA). The activity of plasma membrane Ca 2+ -ATPase during AlF 4 - stimulation was not significantly different from that during CCK stimulation. After partial inhibition of SERCA with 1 nM thapsigargin, 20 pM CCK-evoked [Ca 2+ ] i oscillations were dependent on extracellular Ca 2+ . This study shows that AlF 4 - induces [Ca 2+ ] i oscillations, probably by inositol 1,4,5-trisphosphate production via G protein activation but that these oscillations are strongly dependent on extracellular Ca 2+ as a result of the partial inhibition of SERCA.
Type of Medium:
Online Resource
ISSN:
0363-6143
,
1522-1563
DOI:
10.1152/ajpcell.00566.2002
Language:
English
Publisher:
American Physiological Society
Publication Date:
2003
detail.hit.zdb_id:
1477334-X
SSG:
12
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