|
| |
|
|
|
|
||||
| Home Help Feedback Subscriptions Archive Search Table of Contents | ||||
Journal of Experimental Biology, Vol 134, Issue 1 201-218, Copyright © 1988 by Company of Biologists
JOURNAL ARTICLES |
RP Henry, NJ Smatresk and JN Cameron
Department of Zoology and Wildlife Science, Auburn University, AL 36849.
Carbonic anhydrase (CA) activity was assayed in lysed erythrocytes and in branchial cytoplasm, mitochondria and microsomes of the channel catfish, Ictalurus punctatus. Branchial CA activity was highest in the cytoplasmic fraction, but activity was very low in mitochondria and microsomes. Erythrocyte CA activity was over four-fold greater than that in the gills. Intact animals were injected with the CA inhibitors acetazolamide and benzolamide. Slow, intra-arterial injection of both inhibitors elicited transient side effects of apnoea, bradycardia and hypoxaemia. Acetazolamide and benzolamide induced a mixed but primarily respiratory acidosis. The onset and the time course of the acidosis were correlated with the inhibition of erythrocyte CA; acetazolamide acted faster because it is more freely diffusible than benzolamide. The acid-base disturbance in the blood reached its maximum after 2 h; compensation was delayed until 24 h, when CA inhibition began to disappear. We conclude from these results that there is very little, if any, membrane-associated CA in the gill, and that the branchial enzyme is not quantitatively important in directly converting plasma HCO3- to CO2 for excretion. Rather, CO2 excretion is accomplished via the traditional chloride shift, followed by intracellular dehydration of HCO3- by erythrocyte CA. These results also suggest that branchial cytoplasmic CA inhibition might impair ion transport processes that are used to compensate blood acid-base disturbances and thus delay compensation of the respiratory acidosis.
This article has been cited by other articles:
|
|
 |
|
  K. M. Gilmour, M. Bayaa, L. Kenney, B. McNeill, and S. F. Perry Type IV carbonic anhydrase is present in the gills of spiny dogfish (Squalus acanthias) Am J Physiol Regulatory Integrative Comp Physiol, January 1, 2007; 292(1): R556 - R567. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Georgalis, S. F. Perry, and K. M. Gilmour The role of branchial carbonic anhydrase in acid-base regulation in rainbow trout (Oncorhynchus mykiss) J. Exp. Biol., February 1, 2006; 209(3): 518 - 530. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. J. Esbaugh, S. F. Perry, M. Bayaa, T. Georgalis, J. Nickerson, B. L. Tufts, and K. M. Gilmour Cytoplasmic carbonic anhydrase isozymes in rainbow trout Oncorhynchus mykiss: comparative physiology and molecular evolution J. Exp. Biol., May 15, 2005; 208(10): 1951 - 1961. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Henry Environmentally mediated carbonic anhydrase induction in the gills of euryhaline crustaceans J. Exp. Biol., January 3, 2001; 204(5): 991 - 1002. [Abstract] [PDF]
|
|
|
|
|
|
J. McKendry and S. Perry Cardiovascular effects of hypercarbia in rainbow trout (Oncorhynchus mykiss): a role for externally oriented chemoreceptors J. Exp. Biol., January 1, 2001; 204(1): 115 - 125. [Abstract] [PDF]
|
|
|
|
|
|
T Peters, F Papadopoulos, H. Kubis, and G Gros Properties of a carbonic anhydrase inhibitor protein in flounder serum J. Exp. Biol., January 10, 2000; 203(19): 3003 - 3009. [Abstract] [PDF]
|
|
|
|
|
|
S. Perry, K. Gilmour, N. Bernier, and C. Wood Does gill boundary layer carbonic anhydrase contribute to carbon dioxide excretion: a comparison between dogfish (Squalus acanthias) and rainbow trout (Oncorhynchus mykiss) J. Exp. Biol., January 3, 1999; 202(6): 749 - 756. [Abstract] [PDF]
|
|
|
|
 |
|
 S. Sender, K. Böttcher, Y. Cetin, and G. Gros Carbonic Anhydrase in the Gills of Seawater- and Freshwater-acclimated Flounders Platichthys flesus: Purification, Characterization, and Immunohistochemical Localization J. Histochem. Cytochem., January 1, 1999; 47(1): 43 - 50. [Abstract] [Full Text]
|
|
