INDUCTION OF CA2+ OSCILLATIONS BY SELECTIVE, U73122-MEDIATED, DEPLETION OF INOSITOL-TRISPHOSPHATE-SENSITIVE CA2+ STORES IN RABBIT PANCREATIC ACINAR-CELLS

被引:46
作者
WILLEMS, PHGM
VANDEPUT, FHMM
ENGBERSEN, R
BOSCH, RR
VANHOOF, HJM
DEPONT, JJHHM
机构
[1] Department of Biochemistry, University of Nijmegen, HB Nijmegen, NL-6500
来源
PFLUGERS ARCHIV-EUROPEAN JOURNAL OF PHYSIOLOGY | 1994年 / 427卷 / 3-4期
关键词
PANCREATIC ACINAR CELL; CHOLECYSTOKININ-OCTAPEPTIDE; JMV-180; U73122; THAPSIGARGIN CA2+ OSCILLATIONS; PERMEABILIZED ACINAR CELLS;
D O I
10.1007/BF00374529
中图分类号
Q4 [生理学];
学科分类号
071003 ;
摘要
The effect of the putative inhibitor of phospholipase C activity, U73122, on the Ca2+ sequestering and releasing properties of internal Ca2+ stores was studied in both permeabilized and intact rabbit pancreatic acinar cells. U73122 dose dependently inhibited ATP-dependent Ca2+ uptake in the inositol (1,4,5)-trisphosphate-[Ins(1,4,5)P-3]-sensitive, but not the Ins(1,4,5)P-3-insensitive, Ca2+ store in acinar cells permeabilized by saponin treatment. In a suspension of intact acinar cells, loaded with the fluorescent Ca2+ indicator, Fura-2, U73122 alone evoked a transient increase in average free cytosolic Ca2+ concentration ([Ca2+](i,av)), which was largely independent of external Ca2+. Addition of U73122 to cell suspensions prestimulated with either cholecystokinin octapeptide or JMV-180 revealed an inverse relationship in size between the U73122- and the agonist-evoked [Ca2+](i,av) transient. Moreover, thapsigargin-induced inhibition of intracellular Ca2+-ATPase activity resulted in a [Ca2+](i,av) transient, the size of which was not different following maximal prestimulation with either U73122 or agonist. These observations suggest that U73122 selectively affects the Ins(1,4,5)P-3- casu quo agonist-sensitive internal Ca2+ store, whereas thapsigargin affects both the Ins(1,4,5)P-3-sensitive and -insensitive Ca2+ store. Digital-imaging microscopy of Fura-2-loaded acinar cells demonstrated that U73122, in contrast to thapsigargin, evoked sustained oscillatory changes in [Ca2+](i). The U73122-evoked oscillations were abolished in the absence of external Ca2+. The ability of U73122 to generate external Ca2+-dependent Ca2+ oscillations suggests that depletion of the agonist-sensitive store leads to an increase in Ca2+ permeability of the plasma membrane and that the Ins(1,4,5)P-3-insensitive Ca2+ pool is necessary for the Ca2+ oscillations.
引用
收藏
页码:233 / 243
页数:11
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