Visualization of Calcium Dynamics in Kidney Proximal Tubules

Szebényi, Kornélia and Füredi, András and Kolacsek, Orsolya and Csohány, Rózsa and Prókai, Ágnes and Kis-Petik, Katalin and Szabó, Attila and Bősze, Zsuzsanna and Bender, Balázs and Tóvári, József and Enyedi, Ágnes and Orbán, Tamás I. and Apáti, Ágota and Sarkadi, Balázs (2015) Visualization of Calcium Dynamics in Kidney Proximal Tubules. JOURNAL OF THE AMERICAN SOCIETY OF NEPHROLOGY, 26 (xx). xx-xx. ISSN 1046-6673

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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.

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