pH dependent uptake of porphyrin-type photosensitizers by solid tumor cells in vitro is not induced by modification of transmembrane potential.
The uptake of HpIX, TPPS2a and mTHPC by WiDr, THX cells and skin fibroblasts at pH 7.4 and 6.8 was compared. In the absence of serum, the uptake of HpIX was higher at lower pH. The difference was significant in WiDr cells (P < 0.01) and skin fibroblasts (P < 0.05). TPPS2a nor mTHPC showed any pH dependent uptake. Lowering the extracellular pH resulted in a significant depolarization (3-8 mV) of the cells. Application of tetraethylammonium chloride did not affect the cellular uptake of any of the photosensitizers. We conclude that the pH dependent uptake of photosensitizers is not mainly related to altered transmembrane potential.
Cunderlíková
Beata
B
Department of Biophysics, Institute for Cancer Research, Montebello, N-0310 Oslo, Norway. beata@ilc.sk
Moan
Johan
J
Sjaastad
Ivar
I
D045744:Cell Line, Tumor; D005347:Fibroblasts / Q000378:metabolism*; D006415:Hematoporphyrins / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008564:Membrane Potentials; D008652:Mesoporphyrins / Q000378:metabolism*; D017319:Photosensitizing Agents / Q000378:metabolism*; D011166:Porphyrins / Q000378:metabolism*; D012867:Skin / Q000166:cytology; D019789:Tetraethylammonium
D006415:Hematoporphyrins; D008652:Mesoporphyrins; D017319:Photosensitizing Agents; D011166:Porphyrins; C425082:di(4-sulfonatophenyl)diphenylporphine; D019789:Tetraethylammonium; C072269:temoporfin