Leakage of incorporated radiolabelled adenine--a marker for drug-induced damage of macrofilariae in vitro.
An objective in vitro assay has been developed for quantifying drug-induced damage in Dipetalonema viteae macrofilariae. The method involves radiolabelling the worms ATP pool by incubating macrofilariae with [U-14C]-adenine. As determined by HPLC 72% of the incorporated label was in ATP, 15% in ADP and about 4% in each of NAD and AMP. Macrofilariae labelled with [U-14C]-adenine show a linear efflux of [14C]-label amounting to 21.3% of the total incorporation (mainly as uncharged catabolites) over a time course of 120 h in vitro incubation. When prelabelled worms were exposed to compounds exerting macrofilaricidal effects in vitro a marked stimulation in the leakage of [14C]-label from the worms was noted. The [14C]-label leakage appears to be linked with membrane (or cuticle) damage and the reduction of macrofilarial ATP levels. Determination of the amount of [14C]-label remaining in drug-treated worms relative to appropriate control provides a simple, sensitive and quantitative measure of drug-induced damage in macrofilariae (including Onchocerca). The method has been used to describe the macrofilaricidal activity of a wide range of antifilarial standards, membrane disruptive agents, respiratory inhibitors, fasciolicides and anti-cestode compounds.
Comley
J C
JC
Department of Molecular Sciences, Wellcome Research Laboratories, Kent, U.K.
Rees
M J
MJ
O'Dowd
A B
AB
D000225:Adenine / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000871:Anthelmintics / Q000494:pharmacology*; D002009:Brugia / Q000187:drug effects / Q000378:metabolism; D004153:Dipetalonema / Q000187:drug effects* / Q000378:metabolism; D005260:Female; D005369:Filaricides / Q000494:pharmacology*; D008297:Male; D008842:Microfilariae / Q000187:drug effects / Q000378:metabolism; D009854:Onchocerca / Q000187:drug effects / Q000378:metabolism
D000871:Anthelmintics; D005369:Filaricides; D000255:Adenosine Triphosphate; D000225:Adenine