SELECTIVE STAGE-SPECIFIC CHANGES IN THE PERMEABILITY TO SMALL HYDROPHILIC SOLUTES OF HUMAN-ERYTHROCYTES INFECTED WITH PLASMODIUM-FALCIPARUM
SELECTIVE STAGE-SPECIFIC CHANGES IN THE PERMEABILITY TO SMALL HYDROPHILIC SOLUTES OF HUMAN-ERYTHROCYTES INFECTED WITH PLASMODIUM-FALCIPARUM
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DOI：
10.1016/0166-6851(85)90048-9
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发表时间：
1985-01-01
影响因子：
1.5
通讯作者：
WILSON, RJM
中科院分区：
文献类型：
--
作者：
ELFORD, BC;HAYNES, JD;WILSON, RJM
The permeability characteristics of P. falciparum-infected human erythrocytes to various 3H-labeled solutes were measured during the maturation of the parasites in sorbitol-synchronized cultures. Using [14C]insulin as the extracellular marker, estimates were made of the influx kinetics of [3H]amino acids into trichloroacetic acid (TCA)-soluble pools within the erythrocyte and concomitant incorporation into TCA-precipitable material. These measurements provided values of the rates of protein synthesis by the parasite and the initial influx rates of the transport of precursor amino acids into the erythrocyte. For about 12-15 h after parasitisation, the influx of L-[3H]glutamine remained at a low level comparable to that in the uninfected cell (2-9 nmol/g-1 per min). As pigment appeared in the trophozoite, the initial rate of influx of L-glutamine increased to a value up to 100-fold higher than in the uninfected erythrocyte. The increase in permeability affected only the parasitized cells in a culture of partially infected erythrocytes, and was selective with respect to substrate since the influx kinetics for both [3H]isoleucine and [3H]arginine were not affected by parasitization. The permeability changes occurred mainly over a 4-8 h period in the development of the young trophozoite, during which time [3H]glycine influx was enhanced by a factor of 3-10, with a comparable increase in the uptake of myo-[3H]inositol L-[3H]glutamate, which did not penetrate significantly into uninfected erythrocytes, entered red cells infected with mature trophozoites at a rate which was .ltorsim. 1% of the parasite-induced-L-glutamine influx. At the stages when the permeability to L-glutamine was markedly enhanced, parasitized cells remained impermeable to [3H]sucrose. An analysis of the relative 3H activities in glutathione and free amino acid pools indicated that, if L-glutamine permeation did not increase during parasite maturation beyond the ring stage, or was blocked by a potential antimalarial compound, an insufficient supply of L-glutamine would be available for the increased rates of parasite protein synthesis and glutathione turnover within the red cell.
