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Updated: Apr 16, 2026
Single-channel Analysis and Calcium Imaging in the Podocytes of the Freshly Isolated Glomeruli
Published on: June 27, 2015
Visualization of Calcium Dynamics in Kidney Proximal Tubules
Kornélia Szebényi1, András Füredi1, Orsolya Kolacsek1
1Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary;
Abstract:
Intrarenal changes in cytoplasmic calcium levels have a key role in determining pathologic and pharmacologic responses in major kidney diseases. However, cell-specific delivery of calcium-sensitive probes in vivo remains problematic. We generated a transgenic rat stably expressing the green fluorescent protein-calmodulin-based genetically encoded calcium indicator (GCaMP2) predominantly in the kidney proximal tubules. The transposon-based method used allowed the generation of homozygous transgenic rats containing one copy of the transgene per allele with a defined insertion pattern, without genetic or phenotypic alterations. We applied in vitro confocal and in vivo two-photon microscopy to examine basal calcium levels and ligand- and drug-induced alterations in these levels in proximal tubular epithelial cells. Notably, renal ischemia induced a transient increase in cellular calcium, and reperfusion resulted in a secondary calcium load, which was significantly decreased by systemic administration of specific blockers of the angiotensin receptor and the Na-Ca exchanger. The parallel examination of in vivo cellular calcium dynamics and renal circulation by fluorescent probes opens new possibilities for physiologic and pharmacologic investigations.
Insights
Researchers developed a new transgenic rat model to study kidney calcium levels in real-time. This tool helps investigate kidney diseases and test potential drug treatments for improved patient outcomes.
Area of Science:
- Nephrology
- Molecular Biology
- Biomedical Engineering
Background:
- Intrarenal calcium levels are critical in kidney disease pathology and drug response.
- Challenges exist in delivering calcium-sensitive probes to specific kidney cells in vivo.
- Proximal tubules play a vital role in kidney function and disease.
Purpose of the Study:
- To develop a reliable method for cell-specific in vivo calcium imaging in the kidney.
- To create a transgenic rat model expressing a genetically encoded calcium indicator (GCaMP2) in proximal tubules.
- To investigate real-time changes in intracellular calcium dynamics in kidney proximal tubules.
Main Methods:
- Generation of a transgenic rat line using a transposon-based method for stable GCaMP2 expression in kidney proximal tubules.
- Utilized in vitro confocal and in vivo two-photon microscopy for calcium imaging.
- Administered specific blockers for angiotensin receptor and Na-Ca exchanger to assess their effects on calcium levels.
Main Results:
- Successfully generated homozygous transgenic rats with defined GCaMP2 insertion and no adverse effects.
- Observed a transient increase in proximal tubule cellular calcium during renal ischemia.
- Demonstrated that reperfusion caused a secondary calcium load, reduced by angiotensin receptor and Na-Ca exchanger blockers.
Conclusions:
- The developed transgenic rat model enables precise, real-time monitoring of intracellular calcium in kidney proximal tubules.
- This model provides a powerful platform for studying kidney physiology and pharmacology in vivo.
- Findings highlight the therapeutic potential of targeting angiotensin receptors and Na-Ca exchangers in acute kidney injury.
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