HETEROGENEITY OF CAFFEINE-SENSITIVE AND BRADYKININ-SENSITIVE CA2+ STORES IN VASCULAR ENDOTHELIAL-CELLS

被引:30
作者
GRAIER, WF
SIMECEK, S
BOWLES, DK
STUREK, M
机构
[1] UNIV MISSOURI, DALTON RES CTR, VASC CELL BIOPHYS LAB, COLUMBIA, MO 65211 USA
[2] UNIV MISSOURI, SCH MED, DEPT PHYSIOL, COLUMBIA, MO 65211 USA
关键词
D O I
10.1042/bj3000637
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
The filling state of Ca2+ stores in endothelial cells regulates Ca2+ entry. The functional relationship between the major Ca2+ stores [i.e. Ins(1,4,5)P-3-sensitive (= bradykinin-sensitive stores,'BsS') and caffeine-sensitive stores] is unknown. In pig right-coronary-artery endothelial cells, caffeine failed to release Ca2+ in 68% of the cells (quiet-responders), but increased bradykinin (Bk)induced Ca2+ release 2.5-fold. In Bk-pre-stimulated cells, caffeine increased Ca2+ release upon a second stimulation with Bk 3.2-fold. In quiet-responders caffeine alone did not affect net Ca2+ storage, whereas Bk or caffeine followed by Bk decreased the intracellular Ca2+ pool to 45% and 15%, respectively. Blockade of the endoplasmic-reticulum Ca2+ pump by thapsigargin unmasked the effect of caffeine in quiet-responders, resulting in a transient increase in intracellular free Ca2+ concentration ([Ca2+](i)). In 37% of the cells caffeine alone transiently increased [Ca2+](i) and depleted BsS. This study suggests a heterogeneity in functional organization of endothelial Ca2+ stores. In quiet-responders, caffeine translocates Ca2+ towards the BsS, whereas in overt-responders caffeine empties the BsS.
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页码:637 / 641
页数:5
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