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1 September 2002 Significant Differences Between Procyclic and Bloodstream Forms of Trypanosoma brucei in the Maintenance of their Plasma Membrane Potential
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Abstract

The plasma membrane potential (ΔΨ) of procyclic and bloodstream trypomastigotes of Trypanosoma brucei was studied using the potentiometric fluorescent dye bisoxonol. Our results suggest that a proton pump plays a significant role in the regulation of ΔΨ in procyclic and bloodstream forms, as evidenced by depolarization of the plasma membrane by H -ATPase inhibitors (e.g. dicyclohexylcarbo-diimide, N-ethylmaleimide, diethylstilbestrol, and bafilomycin A1). In bloodstream stages the plasma membrane was significantly depolarized by ouabain only when the cells were incubated in sodium-rich buffers indicating that a sodium pump was being inhibited. In contrast, ouabain had no effect on the ΔΨ of the procyclic stages in a sodium-rich buffer. However, it induced an additional significant depolarization in these stages when their plasma membrane was already partially depolarized by the H -ATPase inhibitor dicyclohexylcarbo-diimide, indicating the presence of an ouabain-sensitive sodium pump whose activity is masked by the H -ATPase. Unlike procyclic forms, the ΔΨ of bloodstream-stage trypomastigotes was markedly sensitive to extracellular Na and K concentrations. Thus, there are significant differences between procyclic and blooodstream forms in the maintenance of the ΔΨ and in their permeability to cations.

NICOLE VAN DER HEYDEN and ROBERTO DOCAMPO "Significant Differences Between Procyclic and Bloodstream Forms of Trypanosoma brucei in the Maintenance of their Plasma Membrane Potential," The Journal of Eukaryotic Microbiology 49(5), (1 September 2002). https://doi.org/10.1111/j.1550-7408.2002.tb00220.x
Received: 8 April 2002; Accepted: 18 July 2002; Published: 1 September 2002
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