Chloride and bicarbonate transport in chick embryonic red blood cells.

Abstract

1. Unidirectional efflux of 36Cl‐ and H14CO3‐ from erythrocytes of 4‐ to 16‐day‐old chick embryos was measured under steady‐state conditions at 37 degrees C and pH 7.7. The efflux rates were high, > 3 s‐1, and were, therefore, measured by means of the continuous flow tube method. 2. At day 4 of development the range of permeability coefficients for bicarbonate and chloride (PHCO3 and PCl was 1‐30 x 10(‐4) cm s‐1, with average values of respectively 10 x 10(‐4) and 8 x 10(‐4) cm s‐1. However, the results can be divided into two groups, one with PHCO3 and PCl above 12 x 10(‐4) cm s‐1, and one with values below 5 x 10(‐4) cm s‐1. The same range of values was also obtained for day 6 erythrocytes, but the overlap is more conspicuous. At day 16, PHCO3 and PCl were respectively 9 x 10(‐4) and 6 x 10(‐4) cm s‐1 (37 degrees C, pH 7.7). In adult chicken red blood cells PHCO3 and PCl were respectively 7 x 10(‐4) and 4 x 10(‐4) cm s‐1, and in human red blood cells the respective values were 5.6 x 10(‐4) and 4 x 10(‐4) cm s‐1. 3. Chloride self‐exchange, measured at 0 degrees C, was almost completely inhibited by addition of 1 mM 4,4'‐diisothiocyanostilbene‐2,2'‐disulphonate (DIDS) at both days 6 and 16 of embryonic development, supporting the finding that the embryonic chick erythrocytes also have a transmembrane anion exchanger similar to that of other red cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Carbon Dioxide Transport and Carbonic Anhydrase in Blood and Muscle

“…Ϫ permeability of the human red blood cell (e.g., Refs. 19,30,88,103), most of which yielded numbers very similar to that of Sieger et al (160), as cited in Table 3. Estimating the physiologically possible HCO 3 Ϫ flux across the red cell membrane in a fashion analogous to that used above for CO 2 , one obtains the following: P HCO 3 Ϫ ϫ c HCO 3 Ϫ ϭ 5 ϫ 10 Ϫ4 cm/s ϫ 10 mM ϭ 5 ϫ 10 Ϫ6 mmol⅐cm Ϫ2 ⅐s Ϫ1 , which is ϳ10 times less than the maximal flux of 6 ϫ 10 Ϫ5 mmol⅐cm Ϫ2 ⅐s Ϫ1 estimated above from turnover number and number of copies of capnophorin per red blood cell but more than two orders of magnitude smaller than the above CO 2 flux.…”

“…Values of HCO 3 Ϫ permeability of erythrocyte membranes are similar for humans and birds (as well as in several other species). In red blood cells of adult humans and of chicken HCO 3 Ϫ permeability (P HCO 3 Ϫ) was measured to be 5.6 ϫ 10 Ϫ4 and 7 ϫ 10 Ϫ4 cm/s, respectively (160). These latter authors showed that a functionally active band 3 protein is present in the erythrocyte membrane of the chicken at very early stages of development.…”

Microscale mechanisms of gas exchange in fruit tissue

“…References: 1, Lide (1999); 2, Gunning & Steer (1996); 3, Uchida et al (1992); 4, Geers & Gros (2000); 5, Jolly (1985); 6, Ho et al (2006a); 7, Lammertyn et al (2001b); 8, Gutknecht et al (1977); 9, Sieger et al (1994). Ho et al (2008).…”

Enhanced Oxalate Transport in Nucleated Red Blood Cells

“…The exchanger has not been influenced by monovalent anion chloride other than bicarbonate. Transport of anions, namely chloride and bicarbonate in chicken RBC, has been reported to be comparable to that of human RBC [17]. The oxalate exchange system may be mediated through specific oxalate binding protein since the human as well as chicken RM, NM and nuclear basic proteins bind oxalate.…”