Division of Kidney and Hypertension, Department of Internal Medicine, The Jikei University School of Medicine, Tokyo, Japan.
Clin Exp Nephrol. 2012 Jun;16(3):389-98. doi: 10.1007/s10157-012-0588-4. Epub 2012 Jan 26.
The kidney is a major organ involved in calcium (Ca(2+)) metabolism. Ca(2+) is transported through renal tubular epithelial cells. The intracellular free calcium concentration (Ca(2+)) is tightly controlled at a low concentration, but transient increases and oscillations in Ca(2+) are induced by various conditions. In this study, we investigated the mechanisms underlying the spontaneous Ca(2+) oscillations observed in MDCK cells.
Ca(2+) was monitored in fura-2-loaded Madin-Darby canine kidney (MDCK) cells using a calcium imaging system. We investigated the mechanism by which Ca(2+) changed by applying drugs or by changing the extracellular Ca(2+) concentration.
Spontaneous Ca(2+) oscillations occurred in MDCK cells. The oscillations occurred irregularly and were not transmitted to neighboring cells. Spontaneous Ca(2+) oscillations in MDCK cells were initiated by Ca(2+) release from ryanodine/IP(3)-sensitive intracellular calcium stores, and their frequency was largely unaffected by the extracellular Ca(2+) concentration. Moreover, the frequency of the oscillations was increased by extracellular nucleotide, but was decreased when the nucleotides were removed.
Our study suggested that Ca(2+) release from ryanodine/IP(3)-sensitive intracellular calcium stores mediates spontaneous Ca(2+) oscillations in MDCK cells. Calcium oscillations may be associated with the function of the renal tubular epithelial cells.
肾脏是参与钙（Ca(2+)）代谢的主要器官。Ca(2+) 通过肾小管上皮细胞进行转运。细胞内游离钙浓度(Ca(2+))被严格控制在低浓度，但Ca(2+)的瞬时增加和波动是由各种条件诱导的。在这项研究中，我们研究了观察到的 MDCK 细胞中自发的Ca(2+)波动的机制。
使用钙成像系统监测负载 fura-2 的 Madin-Darby 犬肾（MDCK）细胞中的Ca(2+)。我们通过应用药物或改变细胞外 Ca(2+)浓度来研究Ca(2+)变化的机制。
MDCK 细胞中发生自发的Ca(2+)波动。波动不规则发生，不会传递到相邻细胞。MDCK 细胞中的自发Ca(2+)波动是由 Ryanodine/IP(3)敏感的细胞内钙库中的 Ca(2+)释放引发的，其频率在很大程度上不受细胞外 Ca(2+)浓度的影响。此外，细胞外核苷酸增加了波动的频率，但当核苷酸被去除时，频率降低。
我们的研究表明，Ryanodine/IP(3)敏感的细胞内钙库中的 Ca(2+)释放介导了 MDCK 细胞中的自发Ca(2+)波动。钙波动可能与肾小管上皮细胞的功能有关。
