Comparisonof Specificityof Inhibitionof PolyamineSynthesisin BovineLymphocytesby EthylglyoxalBis(guanylhydrazone) and MethylglyoxalBis(guanylhydrazone)1

Ethylglyoxal bis(guanylhydrazone) (EGBG) was compared as an inhibitor of polyamine biosynthesis with methylglyoxal bis(guanylhydrazone) (MGBG) in bovine small lymphocytes stim ulated by concanavalin A. EGBG brought about a decrease in spermidine and spermine levels equal to that found with MGBG, but at a 5-fold lower intracellular drug concentration. Despite identical polyamine levels, the degree of inhibition of DNA and protein synthesis by EGBG was smaller than that observed with MGBG, in either the presence or absence of the ornithine decarboxylase inhibitor, «-difluoromethylornithine. It was found that in vitro protein synthesis and in vivo mitochondria! function were inhibited by concentrations of MGBG necessary to inhibit polya mine synthesis in cells (1 to 3 mu), but not by efficacious levels of EGBG (0.2 to 0.6 HIM). These results suggest that EGBG is more suitable as a specific inhibitor of polyamine biosynthesis and that use of this drug, rather than MGBG, in combination with a-difluoromethylornithine may be useful for studying the physio logical functions of polyamines in animal cells.