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Spontaneous [Ca 2+ ] i oscillations reflect nucleotide release from cultured and intact renal epithelia
Author(s) -
Leipziger Jens,
Odgaard Elvin,
Jensen Mikkel Erik Juul,
Overgaard Morten T.,
Geyti Christine Stride,
Praetorius Helle A
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.a1327-c
Subject(s) - extracellular , apyrase , biophysics , receptor , nucleotide , chemistry , paracrine signalling , tubule , purinergic receptor , biology , kidney , biochemistry , endocrinology , gene
We have shown that tubular flow triggers a mechano‐sensory release of nucleotides and subsequent P2Y2 receptor‐mediated [Ca 2+ ] i signalling in mouse medullary thick ascending limb (JASN 16: 2005, 115A). Here we report that isolated perfused mTAL tubules from wild‐type mice display a lively [Ca 2+ ] i oscillatory behaviour. [Ca 2+ ] i oscillations were visible in video‐microscopy as spontaneous “blinking” (increase in fura‐2 ratio or Fluo‐4 intensity increases) randomly distributed in single cell areas over the entire length of the tubule ( 300 μm). We found that [Ca 2+ ] i oscillatory activity: 1. had a frequency of 0.12 Hz, 2. was reduced by < 65% in mTAL of P2Y2 receptor deficient mice, 3. the single oscillatory amplitude was significantly larger in P2Y2 receptor containing mice 4. was strictly dependent on physiological temperature (absent at 12°C) and 5. was strictly dependent on the presence of basolateral Ca 2+ . Very similar [Ca 2+ ] i oscillatory behaviour was found in MDCK cells grown on glass measured at 37°C. Oscillatory activity was seen in 10.9 ± 6.7% of all cells. Scavenging of extracellular ATP with apyrase greatly reduced this activity to 2.1 ± 1.3%. Inhibiting extracellular ATP breakdown with ARL 67156 greatly increased this activity to 27.0 ± 0.26%. These data show that intact and cultured renal epithelia display lively spontaneous [Ca 2+ ] i oscillatory activity and our data strongly indicate that this is caused by spontaneous release of nucleotides and subsequent activation of P2 receptors. Thus, these results image the local auto‐ and paracrine signalling phenomon of the renal tubule.