Inhibition of Na+, K+-ATPase activates swelling-induced taurine efflux in a human neuroblastoma cell line.
The Na+ pump (Na+, K+-ATPase) has been implicated in the regulation of many cellular functions, including cell volume regulation. The effects of inhibiting Na+ pump activity on cell volume and taurine efflux were evaluated in the human neuroblastoma cell line CHP-100. Cell volume changes monitored with the Coulter Multisizer technique and confocal microscopy showed that neuroblastoma cells exposed to ouabain swelled by 22 +/- 4% (n = 5). The rapid cell swelling was followed by regulatory volume decrease (RVD). In cells treated with ouabain, 14C-taurine efflux increased by 183 +/- 11% compared with controls. However, cells exposed simultaneously to ouabain and hypoosmotic solution resulted in a 14C-taurine efflux of 207 +/- 18%. Western blot and immunofluorescence microscopy with specific monoclonal antibodies for the catalytic alpha isoforms of Na+, K+-ATPase demonstrated high levels of the ubiquitously expressed alpha1 and the neuronal-specific alpha3. Ouabain-binding data showed that CHP-100 cells express approximately 3 x 10(5) pump units/cell. The present data indicate that efflux of taurine may be involved during volume recovery subsequent to blockade of Na+, K+-ATPase in CHP-100 cells.
Basavappa
S
S
University Laboratory of Physiology, University of Oxford, United Kingdom. shaila.basavappa@mcmail.vanderbilt.edu
Mobasheri
A
A
Errington
R
R
Huang
C C
CC
Al-Adawi
S
S
Ellory
J C
JC
D001692:Biological Transport; D001932:Brain Neoplasms / Q000378:metabolism* / Q000473:pathology; D048429:Cell Size; D006801:Humans; D009447:Neuroblastoma / Q000378:metabolism* / Q000473:pathology; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D013654:Taurine / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D013654:Taurine; D000254:Sodium-Potassium-Exchanging ATPase