Chloride and bicarbonate transport in fetal red cells.

Abstract

SUMMARY1. Chloride (Jc1) and bicarbonate (JHCO 3) self-exchange flux in fetal human red cells was studied at 0-38°C as 36CI-and [14C]HC03-efflux.2. Both at 0 and 38°C Jcl showed a bell-shaped pH dependence with a broad maximum at pH 7-8. Jcl was 997 % inhibited by the binding of 1. x 106 4,4'-diisothiocyanostilbene-2,2'-disulphonate (DIDS) molecules per cell membrane.3. By raising the temperature from 0 to 38°C Jcl, at external concentration (CO) = 150 mm, increased about 200 times to 5 x 10-8 mol/(cm2 s), the half-time of the tracer efflux being 80 ms at 38°C and pH 7-2. Under conditions where CO = (110 mMCl-+ 25 mM-HCO3-), Jcl also increased by about 200 times, while JHCO3 increased only about 100 times, as temperature was raised from 0 to 38 'C.4. The apparent activation energy (EA) of Janion was not constant, but increased gradually with decreasing temperature. Assuming that the change of EA with temperature consists of two components Jcl, under both experimental conditions, had average values of EA = 117-120 under and EA = 73-78 kJ/mol above a 'breaking' point at 15-20°C, while JHCO3 showed an EA = 100 below and EA = 48 kJ/mol above 25 'C.5. We conclude that the anion transport protein becomes built into the membrane at a very early stage of life, and that the kinetics of Janio in fetal red cells show characteristics that are similar to those of adult red cells.6. Our results suggest that the CO2 transport capacity of the fetal blood can be exploited during rest nearly as efficiently as that of adult blood.

Chloride and bicarbonate transport in chick embryonic red blood cells.

“…Interestingly the anion transport system is absent in red cells from lampreys (Ohnishi & Asai, 1985;Ellory, Wolowk & Young, 1987). The study by Brahm & Wimberley (1989) shows that human fetal red cells at the time of parturition have an anion transport system with kinetics very similar to those of adult red cells. In the present study we were able to determine anion transport in red cells from chick embryos between 4 and 16 days of development.…”

“…One approach to the study of maturation of cellular processes is to compare different cell lines, and from studies of HL-60 cell lines it appears that cation transport decreases as the cells mature (S. Dissing, personal communication). A previous study characterizing chloride and bicarbonate transport in fetal erythrocytes from humans (Brahm & Wimberley, 1989) led to the conclusion that erythrocytes at the stage of gestation have the same qualitative and almost the same quantitative anion transport properties as those of adults.…”

“…A previous study characterizing chloride and bicarbonate transport in fetal erythrocytes from humans (Brahm & Wimberley, 1989) led to the conclusion that erythrocytes at the stage of gestation have the same qualitative and almost the same quantitative anion transport properties as those of adults.…”

The control of oxygen affinity in the three human embryonic haemoglobins by respiration linked metabolites

“…This suggestion finds support in studies on both mouse and chick embryoes in which although the band 3 protein is present its capacity to act as an anion transporter is very significantly reduced, particularly at neutral or acid pH [23,24]. As development in the human proceeds to the fetal stage however a fully functional chloride/bicarbonate transport system is developed [25].…”

Enhanced Oxalate Transport in Nucleated Red Blood Cells

“…The transport of chloride and bicarbonate, the physiologically most important anions, is rapid in human red blood cells (RBC) from adult, late fetuses [2] and in adult chicken RBC [3]. Band 3 protein is shown to be involved in the transport of oxalate across the human RBC membrane (RM) [4].…”