Visualization of Calcium Dynamics in Kidney Proximal Tubules

J Am Soc Nephrol. 2015 Nov;26(11):2731-40. doi: 10.1681/ASN.2014070705. Epub 2015 Mar 18.


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.

Keywords: calcium; hypoxia; ischemia-reperfusion; renal ischemia; renal proximal tubule cell.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Genetically Modified
  • Calcium / metabolism*
  • Cytoplasm / metabolism
  • Female
  • Green Fluorescent Proteins / metabolism
  • Homozygote
  • Hypoxia / pathology
  • Ischemia / pathology
  • Kidney / metabolism
  • Kidney / pathology
  • Kidney Cortex / metabolism
  • Kidney Diseases / pathology
  • Kidney Tubules / metabolism
  • Kidney Tubules, Proximal / metabolism*
  • Kidney Tubules, Proximal / pathology
  • Ligands
  • Microscopy, Confocal*
  • Rats
  • Reperfusion Injury
  • Sodium-Calcium Exchanger / metabolism
  • Transgenes*


  • Ligands
  • Sodium-Calcium Exchanger
  • sodium-calcium exchanger 1
  • Green Fluorescent Proteins
  • Calcium