Phase partitioning of beta-bungarotoxin-treated cerebrocortical synaptosomes: quantitation of the toxin-vulnerable population.
beta-Bungarotoxin induces changes in the partition of cerebrocortical synaptosomes in Dextran-poly(ethylene glycol) two-phase systems. The toxin action promotes an increase of the partition percentage of synaptosomes in the upper poly(ethylene glycol) rich phase. This effect was observed in both Dextran T500 and Dextran T40 two-phase systems. In both cases an increase of partition in this upper phase of a discrete amount of the whole synaptosomal population accounts for almost 100% of choline acetyltransferase activity, a marker of cholinergic synaptosomes, appearing in this same phase. This effect is specifically dependent on the toxin action since a control experiment shows that extraction into the upper phase of the synaptosomal preparation carried out by addition of an unspecific ligand (hexaethonium) bound to poly(ethylene glycol), could induce the partition of both the whole choline acetyltransferase activity and synaptosomal material in this upper phase. These results suggest that beta-bungarotoxin specifically induces the partition into the upper phase of a toxin-vulnerable synaptosomal population. Therefore, it has been estimated that 30 or 32% of the total synaptosomal preparation is sensitive to the toxin action, as calculated from the maximal increase in the toxin-treated particles partition obtained in the Dextran T500 or Dextran T40 two-phase systems, respectively.
García-Garayo
J J
JJ
Departamento de Bioquímica y Biología Molecular y Celular, Universidad de Zaragoza, Facultad de Veterinaria, Spain.
Cebrián
J A
JA
Muiño
M T
MT
López-Pérez
M J
MJ
D000818:Animals; D002038:Bungarotoxins / Q000633:toxicity*; D002540:Cerebral Cortex / Q000201:enzymology; D002795:Choline O-Acetyltransferase / Q000032:analysis*; D011092:Polyethylene Glycols; D012756:Sheep; D013574:Synaptosomes / Q000187:drug effects / Q000201:enzymology*
D002038:Bungarotoxins; D011092:Polyethylene Glycols; D002795:Choline O-Acetyltransferase