Effects of oligomycin on glucose utilization and calcium transport in African trypanosomes

Oligomycin (3 microgram ml-1) inhibited glucose utilization in Trypanosoma brucei S42 as shown by measurements of oxygen uptake and pyruvate production. Carbonyl cyanide 3-chlorophenylhydrazone, an uncoupler of oxidative phosphorylation, did not relieve this inhibition, although some relief was afforded by the alternative substrate glycerol. Naturally dyskinetoplastic Trypanosoma evansi MIAG 105 was less sensitive to inhibition by oligomycin although glycerol relief was still observed, relecting the differential sensitivity of the two pathways. With glucose present as the substrate, 45Ca2+ transport was inhibited by oligomycin in T. brucei, but was stimulated in T. evansi. These results are discussed in terms of alternative systems for maintaining cytoplasmic Ca2+ concentrations in normal and dyskinetoplastic strains of trypanosome.