Uncouplers & pH

Jack Owicki jack_owicki at MOLDEV.COM
Fri Aug 9 15:08:42 EST 1996


Reply to Richard Kondo:
>        I wonder whether extracellular acidification could occur as a
>result of proton extrusion.  The source of protons could be
>intracellular lactate, but might also be protons released during ATP
>breakdown (see Dennis et al. (1991) J Mole. Cell. Cardio. 'Protons in
>ischemia: where do they come from; where do they go?' 23:1077-86

ATP hydrolysis does indeed generate a pretty big fraction of a proton at
neutral pH, but that can account only for transient extracellular
acidifications, since the ~1 mM of intracellular ATP gets exhausted
pretty quickly.    If you have sustained extracellular acidification (>1
minute, say), you have to be producing lactic acid or CO2 (considering just
simple catabolism).  At least, this is true if the extracellular fluid
volume is greater than the cytoplasmic volume.

For those interested, we've reviewed the subject of extracellular
acidification in Owicki & Parce (1992) Biosensors and Bioelectronics
7:255-272.


>        CCCP is a protonophore, but is DNP?
Yes.

...Jack





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