The effect of inhibitors on the respiration of Leishmania donovani promastigotes from culture.
Concentrations of cyanide greater than 0.25 mM completely inhibited the oxygen uptake of L. donovani promastigotes in culture (108 cells/ml). The Ki value for cyanide inhibition indicated the presence of a single terminal cytochrome oxidase. In the presence of 3.0 mM amytal oxygen uptake was 74% of that in controls. Antimycin A at 2.3 mu M gave complete inhibition of oxygen uptake. Azide at 3.5 mM halved oxygen uptake but salicylhydroxamic acid at 3.0 mM was totally without effect. It is concluded that the respiration of L. donovani promastigotes is similar to that in mammalian cells; there was no evidence of an alternative terminal oxidase of the type found in African trypanosomes.