Trypanosoma cruzi epimastigotes express the ouabain- and vanadate-sensitive (Na++K+)ATPase activity

The presence of (Na++K+)ATPase activity in CL14 clone and NIH NTY strain of Trypanosoma cruzi epimastigotes is demonstrated. A Na+ plus K+ stimulated ATPase activity is found in both strains. The optimal Na+/K+ ratio is 5:1 and 9:1 in CL14 clone and NIH NTY strain, respectively. In both strains, vanadate completely inhibits the ouabain-sensitive ATPase activity indicating that it belongs to the P-type (E-1/E-2) family of ion-transporting ATPases. The I-50 for vanadate is 0.66 +/- 0.04 and 0.01 +/- 0.02 mu M in CL14 clone and NIH NTY strain, respectively. These data indicate that both strains of T. cruzi epimastigotes express the ouabain- and vanadate-sensitive (Na++K+)ATPase activity. On the other hand, the discrepancy between the parameters analyzed for the inhibitors suggests that they express different isoforms of this enzyme.