Fluorescence analysis of the interaction of isometamidium with Trypanosoma congolense.
Isometamidium chloride (Samorin) is the only compound recommended for prophylaxis against bovine trypanosomiasis in sub-Saharan Africa. The fluorescence property of this compound was used to investigate the interaction of the molecule with in vitro-derived bloodstream forms of Trypanosoma congolense IL 1180. Incubation of isometamidium with trypanosomes at 37 degrees C for 180 min resulted in a gradual alteration of the lambda max. with time (from 600 to 584 nm) and an increase in the intensity of trypanosome-associated fluorescence of approx. 2-fold. The alteration in fluorescence was temperature-dependent and inhibited by the addition of N-ethylmaleimide. In contrast, with intact cells addition of digitonin caused a rapid increase in fluorescence intensity to approximately four times that observed with intact cells. Uptake of isometamidium was also determined using radiolabelled drug; the results indicated that the time course of the uptake process resembled the fluorescence profile and was temperature-dependent. The results therefore indicate that the alteration of fluorescence is due to interaction of isometamidium with an intracellular component(s) and that isometamidium is transported across the plasma membrane via a protein carrier. The data also indicate that the described fluorescence technique can be used to investigate the role of membrane transport in resistance to isometamidium.
Department of Biology, Technion, Israel Institute of Technology, Technion City, Haifa.
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D
Zilberstein
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J
Wilkes
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H
Hirumi
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AS
Peregrine
D000818:Animals; D005033:Ethylmaleimide / Q000494:pharmacology; D051379:Mice; D010617:Phenanthridines / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013696:Temperature; D014344:Trypanocidal Agents / Q000378:metabolism*; D014348:Trypanosoma congolense / Q000378:metabolism*
D010617:Phenanthridines; D014344:Trypanocidal Agents; C000702:isometamidium chloride; D005033:Ethylmaleimide