Lack of effect of added liposomes on veratridine activation of 22Na+ uptake in rat brain synaptosomes.

Partially purified egg yolk phospholipids in the form of both small and large unilamellar liposomes at lipid concentrations of 30 mg/ml and higher inhibited veratridine activation of sodium channel specific 22Na+ uptake by rat brain synaptosomes. Chromatographically purified egg yolk phosphatidyl choline liposomes did not show this inhibition even at lipid concentrations up to 125 mg/ml. This demonstrates that the inhibition of veratridine-activated 22Na+ uptake was due to an impurity in the lipid rather than an ability of the liposomes to absorb and immobilize the lipophilic veratridine molecule.