Two functionally distinct organic osmolyte pathways in Plasmodium gallinaceum-infected chicken red blood cells.
Red cells infected with the human malaria parasite Plasmodium falciparum have an increased permeability to a range of small, structurally unrelated solutes via a malaria-induced pathway. We report here a similar pathway present in parasitised red cells from chickens infected with the avian malaria parasite, Plasmodium gallinaceum. Parasitised cells showed a marked increase in the rate of influx of sorbitol (76-fold) and, to a lesser degree, taurine (3-fold) when compared with red cells from uninfected chickens. Pharmacological data suggest that both sorbitol and taurine are transported via a single malaria-induced pathway, which is sensitive to inhibition by 5-nitro-2-(3-phenylpropylamino)benzoic acid (IC(50) approximately 7 microM). The malaria-induced pathway differed in its inhibition by a range of anion channel inhibitors when compared to the endogenous, volume-activated osmolyte pathway of chicken red cells. There were also differences in the selectivity of sorbitol and taurine by the two permeation routes. The data presented here are consistent with the presence of two distinct organic solute pathways in infected chicken red cells. The first is an endogenous volume-activated pathway, which is not activated by the parasite and the second is a malaria-induced pathway, similar to those that are induced by other types of malaria in other host species.
Staines
Henry M
HM
University Laboratory of Physiology, Parks Road, Oxford OX1 3PT, UK. henry.staines@physiol.ox.ac.uk
Godfrey
Edmund M
EM
Lapaix
Franck
F
Egee
Stéphane
S
Thomas
Serge
S
Ellory
J Clive
JC
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002250:Carbon Radioisotopes; D002463:Cell Membrane Permeability / Q000187:drug effects; D002645:Chickens; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism*; D006367:HeLa Cells; D006461:Hemolysis; D006801:Humans; D007038:Hypotonic Solutions; D007473:Ion Channels / Q000037:antagonists & inhibitors; D008289:Malaria, Avian / Q000097:blood*; D009579:Nitrobenzoates / Q000494:pharmacology; D009994:Osmolar Concentration; D010964:Plasmodium gallinaceum; D013012:Sorbitol / Q000378:metabolism; D013654:Taurine / Q000378:metabolism; D013696:Temperature
D002250:Carbon Radioisotopes; D007038:Hypotonic Solutions; D007473:Ion Channels; D009579:Nitrobenzoates; D013654:Taurine; C058176:5-nitro-2-(3-phenylpropylamino)benzoic acid; D013012:Sorbitol