Ryanodine receptor and capacitative Ca2+ entry in fresh preglomerular vascular smooth muscle cells.
Ryanodine receptor and capacitative Ca2+ entry in fresh preglomerular vascular smooth muscle cells.
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DOI：
10.1046/j.1523-1755.2000.00329.x
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发表时间：
2000-10
影响因子：
19.6
通讯作者：
S. Fellner;W. Arendshorst
中科院分区：
文献类型：
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作者：
S. Fellner;W. Arendshorst
背景多种激素、神经和旁分泌因子通过刺激钙内流或动员来调节肾小球前动脉张力。我们以前提供的证据，容量（存储操作）钙离子进入新鲜肾血管平滑肌细胞（VSMCs）。Ryanodine敏感受体（RyR）最近已被确定在各种非肾血管床。方法采用磁微球/筛分技术分离大鼠肾小球前VSMCs，Fura-2荧光比率法测定细胞内Ca 2+（[Ca 2 +]i）。结果Ryanodine（3 μ mol/L）使[Ca 2 +]i从79增加到138 nmol/L（P = 0.01）。硝苯地平（Nif）在兰尼定之前或之后给药，没有效果。在无钙缓冲液中加入1 mmol/L钙对静息[Ca ~（2+）]i无影响。在含Nif的无钙缓冲液中，加入Ca ~（2+）-ATP酶抑制剂环匹阿尼酸后，[Ca ~（2+）]i从61上升到88 nmol/L，加入Ca ~（2+）（1 mmol/L）后，[Ca ~（2+）]i上升到159 nmol/L。Mn 2+淬灭Ca/fura信号，确认二价阳离子进入。在含Nif的无钙缓冲液中，加入ryanodine后，[Ca ~（2+）]i由80增加到94 nmol/L，加入Ca ~（2+）（1 mmol/L）后，[Ca ~（2+）] i增加到166 nmol/L。Mn 2+淬灭再次显示。因此，排空肌浆网（SR）与ryanodine刺激容量Ca 2+进入。结论肾小球前VSMCs具有功能性RyR，与SRCa 2 +-ATP酶抑制剂一样，Ryanodine耗竭SRCa 2+可激活一种由钙池操作的容性进入机制。
BACKGROUND A multiplicity of hormonal, neural, and paracrine factors regulates preglomerular arterial tone by stimulating calcium entry or mobilization. We have previously provided evidence for capacitative (store-operated) Ca2+ entry in fresh renal vascular smooth muscle cells (VSMCs). Ryanodine-sensitive receptors (RyRs) have recently been identified in a variety of nonrenal vascular beds. METHODS We isolated fresh rat preglomerular VSMCs with a magnetized microsphere/sieving technique; cytosolic Ca2+ ([Ca2+]i) was measured with fura-2 ratiometric fluorescence. RESULTS Ryanodine (3 micromol/L) increased [Ca2+]i from 79 to 138 nmol/L (P = 0.01). Nifedipine (Nif), given before or after ryanodine, was without effect. The addition of calcium (1 mmol/L) to VSMCs in calcium-free buffer did not alter resting [Ca2+]i. In Ca-free buffer containing Nif, [Ca2+]i rose from 61 to 88 nmol/L after the addition of the Ca2+-ATPase inhibitor cyclopiazonic acid and to 159 nmol/L after the addition of Ca2+ (1 mmol/L). Mn2+ quenched the Ca/fura signal, confirming divalent cation entry. In Ca-free buffer with Nif, [Ca2+]i increased from 80 to 94 nmol/L with the addition of ryanodine and further to 166 nmol/L after the addition of Ca2+ (1 mmol/L). Mn2+ quenching was again shown. Thus, emptying of the sarcoplasmic reticulum (SR) with ryanodine stimulated capacitative Ca2+ entry. CONCLUSION Preglomerular VSMCs have functional RyR, and a capacitative (store-operated) entry mechanism is activated by the depletion of SR Ca2+ with ryanodine, as is the case with inhibitors of SR Ca2+-ATPase.