新たに単離した糸球体の足細胞における単一チャネル分析とカルシウムイメージング
Summary
Changes in the intracellular calcium levels in the podocytes are one of the most important means to control the filtration function of glomeruli. Here we explain a high-throughput approach that allows detection of real-time calcium handling and single ion channels activity in the podocytes of the freshly isolated glomeruli.
Abstract
Podocytes (renal glomerular epithelial cells) are known to regulate glomerular permeability and maintain glomerular structure; a key role for these cells in the pathogenesis of various renal diseases has been established since podocyte injury leads to proteinuria and foot process effacement. It was previously reported that various endogenous agents may cause a dramatic overload in intracellular Ca2+ concentration in podocytes, presumably leading to albuminuria, and this likely occurs via calcium-conducting ion channels. Therefore, it appeared important to study calcium handling in the podocytes both under normal conditions and in various pathological states. However, available experimental approaches have remained somewhat limited to cultured and transfected cells. Although they represent a good basic model for such studies, they are essentially extracted from the native environment of the glomerulus. Here we describe the methodology of studying podocytes as a part of the freshly isolated whole glomerulus. This preparation retains the functional potential of the podocytes, which are still attached to the capillaries; therefore, podocytes remain in the environment that conserves the major parts of the glomeruli filtration apparatus. The present manuscript elaborates on two experimental approaches that allow 1) real-time detection of calcium concentration changes with the help of ratiometric confocal fluorescence microscopy, and 2) the recording of the single ion channels activity in the podocytes of the freshly isolated glomeruli. These methodologies utilize the advantages of the native environment of the glomerulus that enable researchers to resolve acute changes in the intracellular calcium handling in response to applications of various agents, measure basal concentration of calcium within the cells (for instance, to evaluate disease progression), and assess and manipulate calcium conductance at the level of single ion channels.
Introduction
腎臓は、様々な物質のための恒常性バランスを維持し、総血圧を決定するようにして血液量を調節します。ハイパーまたは低血圧に至るまでに腎臓濾過、再吸収や分泌リードの障害または付随する病理学的状態は、最終的に腎臓移植を必要とする末期腎疾患を終了します。毛細血管内皮、基底膜および上皮細胞の単電池層- -スリットダイアフラムの完全性と機能1の維持に重要な役割を果たし足細胞、腎フィルタリング部（糸球体）は、3つの層からなります。選択透過性糸球体フィルタにおける機能不全は、蛋白尿などの巨大分子の尿損失の原因となります。種々の薬剤は、糸球体濾過障壁の完全性を決定し、それらの足細胞足突起の構造に影響を及ぼし得ます。
足細胞は、逮捕されるの維持に関与していますeruli濾過機能。これは、足細胞による不適切なカルシウム処理は、細胞損傷につながり、腎2,3の様々な形の進行に重要な役割を果たしていることが確立されています。したがって、細胞内カルシウム濃度の変化の直接測定を可能にするモデルの開発は、足細胞の機能の研究のための手段になります。単離された糸球体は、以前アルブミン反射係数の測定4および全細胞電気生理学的パッチクランプ測定5,6の積分携帯電流の評価を変更するなど、多くの研究で使用しました。本論文では、研究者は、薬剤の用途に応じて、細胞内カルシウム濃度の変化を測定し、細胞内カルシウムの基礎レベルを推定し、個々のカルシウムチャネルの活性を評価することを可能にするプロトコルを記述します。 Ratometricカルシウム濃度の測定値とパッチクランプelectrophysiologyはそれぞれ、足細胞及びチャネル内の活性細胞内カルシウム濃度の変化を決定するために使用しました。
Protocol
Representative Results
Discussion
ここで説明する手法は、げっ歯類の糸球体の足細胞によるカルシウム処理の分析を可能にします。この技術は、パッチクランプ単一チャンネル電気生理学、蛍光レシオメトリック共焦点イメージングの適用を可能にします。しかしながら、両方のアプローチは、それ自体で、別々に使用することができます。提案されたプロトコルは、1）腎フラッシュなど、いくつかの比較的単純なステップ…
Disclosures
The authors have nothing to disclose.
Acknowledgements
著者らは、顕微鏡実験で優れた技術支援のためにグレン·スローカム（ウィスコンシン医科大学）とコリーンA.ラビン（ニコンインスツルメンツ社）を感謝したいと思います。グレゴリー·ブラスは、原稿の重要な校正のために認められています。この研究は、（DVIに）米国腎臓学会から（ASに）1-15-BS-172を付与し、ベン·J·リップス研究員国立衛生研究所の助成金HL108880と米国糖尿病協会によってサポートされていました。
Materials
| Fluo4 AM | Life Technologies | F14217 | 500µl in DMSO |
| FuraRed AM | Life Technologies | F-3020 | |
| Poly-L-lysine | Sigma-Aldrich | P4707 | |
| Pluronic acid | Sigma-Aldrich | F-68 | solution |
| Ionomycin | Sigma-Aldrich | I3909-1ML | |
| Tube rotator | Miltenyi Biotec GmbH | 130-090-753 | Germany |
| Nikon confocal microscope (inverted) | Nikon | Nikon A1R | Laser exitation 488nm. Emission filters 500-550nm and 570-620nm |
| Objective | Nikon | Plan Apo 60x/NA 1.4 Oil | |
| Cover Glass | Thermo Scientific | 6661B52 | |
| High vacuum grease | Dow Corning | Silicone Compound | |
| Software | Nikon | Nikon NIS-Elements | |
| Recording/perfusion chamber | Warner Instruments | RC-26 | |
| Patch Clamp amplifier | Molecular Devices | MultiClamp 700B | |
| Data Acquisition System | Molecular Devices | Digidata 1440A | Axon Digidata® System |
| Low Pass Filter | Warner Instruments | LPF-8 | 8 pole Bessel |
| Borosilicate glass capillaries | World Precision Instruments | 1B150F-4 | |
| Micropipette Puller | Sutter Instrument Co | P-97 | Flaming/Brown type micropipette puller |
| Microforge | Narishige | MF-830 | Japan |
| Motorized Micromanipulator | Sutter Instrument Co | MP-225 | |
| Inverted microscope | Nikon | Eclipse Ti | |
| Microvibration isolation table | TMC | equipped with Faraday cage | |
| Multichannel valve perfusion system | AutoMake Scientific | Valve Bank II | |
| Recording/perfusion chamber | Warner Instruments | RC-26 | |
| Software | Molecular Devices | pClamp 10 . 2 | |
| Nicardipine | Sigma-Aldrich | N7510 | |
| Iberiotoxin | Sigma | I5904-5UG | |
| Niflumic acid | Sigma-Aldrich | N0630 | |
| DIDS | Sigma-Aldrich | D3514-25MG | |
| TEA chloride | Tocris | T2265 | |
| RPMI 1640 | Life Technologies | 11835030 | without antibiotics |
| BSA | Sigma-Aldrich | A8327 | 30% albumin solution |
| Temperature controlled surgical table | MCW core | for rodents | |
| Steel sieves: | #100 (150 μm), 140 (106 μm) | ||
| Gilson, Inc SIEVE 3 SS FH NO200 | Fisher Sci | 50-871-316 | |
| Gilson, Inc SIEVE 3 SS FH NO270 | Fisher Sci | 50-871-318 | |
| Gilson, Inc SIEVE 3 SS FH NO400 | Fisher Sci | 50-871-320 | |
| mesh 200 | Sigma-Aldrich | s4145 | screen for CD-1 |
| Binocular microscope | Nikon | Eclipse TS100 | |
| Binocular microscope | Nikon | SMZ745 | |
| Syringe pump-based perfusion system | Harvard Apparatus | ||
| polyethylene tubing | Sigma-Aldrich | PE50 | |
| Isofluorane anesthesia | http://www.vetequip.com/ | 911103 | |
| Other basic reagents | Sigma-Aldrich |
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