Brevetoxin-3 (PbTx-3) inhibits oxygen consumption and increases Na+ content in mouse liver slices through a tetrodotoxin-sensitive pathway
1994
Rodriguez, F.A. | Escobales, N. | Maldonado, C.
To have insights into possible non-neural effects of PbTx-3 (0.07 micrograms/ml), its effects on various parameters of hepatic metabolism were evaluated. PbTx-3 inhibits oxygen consumption (QO2) in liver slices by 25 +/- 1%, and increases hepatocyte Na+/K+ ratio by 72 +/- 4%. Ouabain, a Na+-K+-pump inhibitor, also reduced QO2 by 19 +/- 2% and raised the Na+/K+ ratio by 77 +/- 4%. The effects of PbTx-3 and ouabain on QO2 and Na+/K+ ratio were not additive, suggesting a role for the Na+-K+-pump in these actions of PbTx-3. However, Na+-K+-pump activity determinations, using 86Rb as a K+ tracer, did not reveal inhibitory effects of this toxin on the transport system. This indicates that the pump is not a target of PbTx-3. The effect of PbTx-3 on liver slices Na+ content was abolished by the sodium channel blocker tetrodotoxin (0.1 micromolar). Tetrodotoxin also antagonized the inhibition of oxygen consumption by PbTx-3. These results suggest that in the liver PbTx-3 can induce effects that appear to be similar to those observed in excitable tissue.
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