In experiments with muscle homogenate we were using FCCP diluted in EtOH and respiration after it seemed to be OK (P/E control ratio about 0,8 - 0,9). But, after diluted of FCCP in DMSO, we have problem - P/E is not even 1, but about 2 and so - in fact, reaction of homogenate to FCCP is insufficient. Do you have any idea what can be wrong?