Tv. Gowda et Jl. Middlebrook, EFFECTS OF MYONECROTIC SNAKE-VENOM PHOSPHOLIPASE-A(2) TOXINS ON CULTURED MUSCLE-CELLS, Toxicon, 31(10), 1993, pp. 1267-1278
We have attempted to establish a cell culture model suitable for molec
ular mechanism of action studies of necrotic phospholipases A2 (PLA2).
Three myonecrotic PLA2 were purified, one basic PLA2 from Naja nigric
ollis venom and two basic PLA2 (VRV-PL-V and VRV-PL-VIIIa) from Vipera
russelli venom. The effects of these PLA2 on several established musc
le cell lines were evaluated. As judged by light microscopy, some, but
not all, cell lines detached from the culture plate in a time- and co
ncentration-related fashion. Naja nigricollis PLA2 was the most potent
at eliciting this effect, followed by VRV-PL-V and VRV-PL-VIIIa. The
two most sensitive cell lines, 1447 and 1456, were chosen for further
study using N. nigricollis PLA2. Cellular protein and nucleic acid syn
theses were inhibited by the toxin in a time- and dose-related manner.
However, it appeared that most, if not all, of the inhibition was due
to toxin-induced reduction of precursor uptake, suggesting effects at
the plasma membrane level. The putative membrane effects were specifi
c, in that uptake of calcium, choline or glucose was not inhibited by
the toxin. Moreover, treating the cells with toxin failed to significa
ntly increase lactate dehydrogenase release into the medium. Polyclona
l antiserum prepared against N. nigricollis basic PLA2 neutralized the
toxicity completely with 1456 cells, but only partially with the 1447
cell line. Both the 1447 and 1456 lines appear to be suitable as cell
culture models for necrotizing PLA2 molecular mechanism of action stu
dies.