TY - JOUR
T1 - Extracellular carbonic anhydrase activity and carbonic anhydrase inhibitors in the circulatory system of fish
AU - Henry, Raymond P.
AU - Gilmour, Kathleen M.
AU - Wood, Chris M.
AU - Perry, Steve F.
N1 - Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 1997
Y1 - 1997
N2 - Carbonic anhydrase activity in the extracellular fluid of lower vertebrates is considered to be minimal, either because of the absence of carbonic anhydrase or because of the presence of naturally occurring inhibitors. The presence of carbonic anhydrase activity and circulating inhibitors was measured in plasma and subcellular fractions of gill tissue in elasmobranchs and teleosts. Plasma carbonic anhydrase activity was confirmed in the former but in extremely low amounts, especially compared with activity in red cells. The activity was correlated with plasma iron concentration and red cell hemolysis, which suggests that it is a by-product of endogenous hemolysis during red cell turnover. A subcellular fraction of dogfish gills rich in microsomes contained significantly higher carbonic anhydrase activity than previously found in teleosts, making elasmobranchs the only aquatic lower vertebrates to possess putative basolateral membrane-associated carbonic anhydrase in the gill vasculature. It is suggested that branchial membrane-associated carbonic anhydrase is correlated more with a pH and/or CO2-sensitive ventilatory drive than with the maintenance of resting CO2 excretion. The occurrence and effectiveness of plasma carbonic anhydrase inhibitors were highly species-specific, with the salmonids having the most potent inhibitor. Cross-reactivity of inhibitor to red cell carbonic anhydrase appeared to be related to phylogenetic proximity. Selection for the presence of carbonic anhydrase inhibitors in fish plasma appears to be the result of multiple physiological pressures, including preservation of red cell intracellular pH, ventilatory control, and red cell fragility.
AB - Carbonic anhydrase activity in the extracellular fluid of lower vertebrates is considered to be minimal, either because of the absence of carbonic anhydrase or because of the presence of naturally occurring inhibitors. The presence of carbonic anhydrase activity and circulating inhibitors was measured in plasma and subcellular fractions of gill tissue in elasmobranchs and teleosts. Plasma carbonic anhydrase activity was confirmed in the former but in extremely low amounts, especially compared with activity in red cells. The activity was correlated with plasma iron concentration and red cell hemolysis, which suggests that it is a by-product of endogenous hemolysis during red cell turnover. A subcellular fraction of dogfish gills rich in microsomes contained significantly higher carbonic anhydrase activity than previously found in teleosts, making elasmobranchs the only aquatic lower vertebrates to possess putative basolateral membrane-associated carbonic anhydrase in the gill vasculature. It is suggested that branchial membrane-associated carbonic anhydrase is correlated more with a pH and/or CO2-sensitive ventilatory drive than with the maintenance of resting CO2 excretion. The occurrence and effectiveness of plasma carbonic anhydrase inhibitors were highly species-specific, with the salmonids having the most potent inhibitor. Cross-reactivity of inhibitor to red cell carbonic anhydrase appeared to be related to phylogenetic proximity. Selection for the presence of carbonic anhydrase inhibitors in fish plasma appears to be the result of multiple physiological pressures, including preservation of red cell intracellular pH, ventilatory control, and red cell fragility.
UR - http://www.scopus.com/inward/record.url?scp=0031282285&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0031282285&partnerID=8YFLogxK
U2 - 10.1086/515878
DO - 10.1086/515878
M3 - Article
C2 - 9361139
AN - SCOPUS:0031282285
VL - 70
SP - 650
EP - 659
JO - Physiological and Biochemical Zoology
JF - Physiological and Biochemical Zoology
SN - 1522-2152
IS - 6
ER -