Calcium-induced calcium release participates in cell volume regulation of rabbit TALH cells

Pflugers Arch. 2002 Mar;443(5-6):754-61. doi: 10.1007/s00424-001-0774-9. Epub 2002 Feb 5.

Abstract

Changes of cell volume and intracellular calcium concentration ([Ca(2+)](i)) in immortalized thick ascending limb of Henle's loop (TALH) cells were monitored using confocal laser scanning microscopy and fura-2 fluorescence, respectively. Reduction of the extracellular osmolarity from 600 to 300 mosmol/l induced cell swelling followed by regulatory volume decrease (RVD). Simultaneously, the [Ca(2+)](i) increased transiently. The calcium rise was not observed in calcium-free solution or in the presence of nifedipine, indicating that the change was, in the first place, due to the activation of a calcium influx. Application of ATP or caffeine in isotonic solutions increased transiently the [Ca(2+)](i) which revealed the existence of stores in TALH cells sensitive to inositol-1,4,5 trisphosphate (IP(3)) and ryanodine. To examine the possibility that the calcium influx might induce calcium release, manganese quenching experiments were performed. In hypotonic calcium-free solutions, the decay of the calcium-insensitive and calcium-sensitive fluorescence occurred simultaneously. In the presence of extracellular calcium however, the calcium-sensitive wavelength revealed initial calcium influx followed by a calcium release from intracellular stores. Thus, the calcium influx was a prerequisite for the calcium release. We conclude that calcium-induced calcium release participates in global calcium signalling during RVD of TALH cells.

MeSH terms

  • Animals
  • Calcium / metabolism*
  • Calcium / pharmacology
  • Calcium Signaling / drug effects
  • Calcium Signaling / physiology*
  • Cell Line
  • Hypotonic Solutions / pharmacology
  • Loop of Henle / cytology*
  • Loop of Henle / metabolism*
  • Osmotic Pressure
  • Rabbits
  • Water-Electrolyte Balance / physiology*

Substances

  • Hypotonic Solutions
  • Calcium