The triphasic volume response of human red cells in low ionic strength media: demonstration of a special bicarbonate transport.
When human red cells are first placed in isotonic media of low ionic strength there is a triphasic volume change. The initial shrinkage (phase A) starting immediately is followed by a rapid reflation (phase B). The final shrinkage (phase C) is slower and has more variable properties. The first two phases need Cl- and HCO3- and they have been shown to involve both the band 3 anion exchanger and the red cell carbonic anhydrase. Phase C is only seen when phase B is present. Both phase B and phase C were accelerated by the lower monohydric alcohols. With methanol the acceleration was maximal near 2M, thereafter inhibition developed. The hypothesis is advanced that phase C involves a permeability for bicarbonate which is independent of the band 3 anion exchanger, and which may be a dimer of carbonic anhydrase. The unique kinetics, the physiological significance, and implications of the special bicarbonate transport system are discussed.
Widdas
W F
WF
Department of Biology, Royal Holloway College, University of London, Egham, Surrey, Great Britain.
Baker
G F
GF
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000438:Alcohols / Q000494:pharmacology; D001457:Anion Exchange Protein 1, Erythrocyte / Q000378:metabolism; D027321:Anion Transport Proteins; D001639:Bicarbonates / Q000097:blood*; D001692:Biological Transport; D002245:Carbon Dioxide / Q000097:blood; D002256:Carbonic Anhydrases / Q000097:blood / Q000737:chemistry; D002352:Carrier Proteins / Q000097:blood; D002463:Cell Membrane Permeability / Q000187:drug effects; D048429:Cell Size / Q000187:drug effects; D002712:Chlorides / Q000097:blood; D003198:Computer Simulation; D004054:Diethylstilbestrol / Q000494:pharmacology; D004912:Erythrocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D004958:Estradiol / Q000494:pharmacology; D005016:Ethoxzolamide / Q000494:pharmacology; D006801:Humans; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D007038:Hypotonic Solutions / Q000494:pharmacology*; D007473:Ion Channels / Q000378:metabolism; D008954:Models, Biological; D015032:Zinc / Q000502:physiology
D000438:Alcohols; D001457:Anion Exchange Protein 1, Erythrocyte; D027321:Anion Transport Proteins; D001639:Bicarbonates; D002352:Carrier Proteins; D002712:Chlorides; D007038:Hypotonic Solutions; D007473:Ion Channels; D002245:Carbon Dioxide; D004958:Estradiol; D004054:Diethylstilbestrol; D002256:Carbonic Anhydrases; D015032:Zinc; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D005016:Ethoxzolamide