Buffering limits plasma HCO3- dehydration when red blood cell anion exchange is inhibited.
Theory suggests that HCO3- dehydration in the plasma of rainbow trout is limited by both the absence of carbonic anhydrase (CA) activity and the low non-bicarbonate buffer capacity of the plasma (betaplasma). The potential for betaplasma to limit plasma HCO3- dehydration was assessed in rainbow trout in which HCO3- dehydration via the red blood cell (RBC) was inhibited using the anion exchange blocker 4,4'-diisothiocyanostilbene-2,2'-disulphonic acid (DIDS). DIDS administration reduced the rate of RBC HCO3- dehydration by 68-80% for at least 6h, resulting in the elevation of arterial CO2 tension (PaCO2) by 3.07 +/- 0.45 Torr (N = 6). Addition of bovine CA to the circulation of DIDS-treated trout caused PaCO2 to decrease significantly. This effect was increased significantly in rainbow trout in which betaplasma was elevated experimentally by intravascular injection of N-[2-hydroxyethyl]piperazine-N'-[2-ethanesulfonic acid] (HEPES), supporting the hypothesis that CA-catalysed HCO3- dehydration in the plasma of rainbow trout is limited by proton availability.
Gilmour
K M
KM
Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ont., Canada K1S 5B6. kgilmour@ccs.carleton.ca
Desforges
P R
PR
Perry
S F
SF
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000704:Analysis of Variance; D000818:Animals; D000838:Anions / Q000378:metabolism*; D001639:Bicarbonates / Q000097:blood*; D001784:Blood Gas Analysis; D002021:Buffers; D002247:Carbon Isotopes / Q000493:pharmacokinetics; D002256:Carbonic Anhydrases / Q000494:pharmacology; D003681:Dehydration / Q000503:physiopathology*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004912:Erythrocytes / Q000166:cytology / Q000378:metabolism*; D006531:HEPES / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D017686:Oncorhynchus mykiss; D010313:Partial Pressure; D010949:Plasma / Q000187:drug effects / Q000378:metabolism*; D012119:Respiration / Q000187:drug effects; D013997:Time Factors
D000838:Anions; D001639:Bicarbonates; D002021:Buffers; D002247:Carbon Isotopes; D002256:Carbonic Anhydrases; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D006531:HEPES