Document Detail

Carbonic anhydrase and CO2 chemoreception in the pulmonate snail Helix aspersa.
MedLine Citation:
PMID:  7817040     Owner:  NLM     Status:  MEDLINE    
We have studied the effects of carbonic anhydrase inhibition on the hypercapnic ventilatory response of the pulmonate snail, Helix aspersa, in an isolated brain-pneumostome preparation. We found that the cell permeant carbonic anhydrase inhibitor, acetazolamide (ACTZ), increased pneumostomal opening and ventilation during normocapnia (2-3% CO2) and decreased the rate of pneumostomal response to step changes in CO2 (4.5%), but did not change the steady-state ventilatory response to elevated CO2 (4.5%) compared to the inactive ACTZ analogue, N2-substituted 2-acetylamino-1,3,4-thiadiazole (Cl 13850). In contrast, the cell impermeant carbonic anhydrase inhibitor, quartenary ammonium sulfonilamide (QAS), had no effect on the pneumostomal response to CO2 compared to Cl 13850. Using Hansson's histochemical technique to stain for carbonic anhydrase activity, we identified a small number of neurons in the subesophageal ganglia that exhibited carbonic anhydrase activity. Some of these cells were in the region of CO2-sensitivity. In conclusion, carbonic anhydrase inhibition slows the ventilatory response to rapid changes in CO2, but does not affect the intrinsic ability of H. aspersa to respond to CO2. The ventilatory effects of carbonic anhydrase inhibition may be attributed to the intracellular actions of the carbonic anhydrase enzyme.
J S Erlichman; E L Coates; J C Leiter
Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Respiration physiology     Volume:  98     ISSN:  0034-5687     ISO Abbreviation:  Respir Physiol     Publication Date:  1994 Sep 
Date Detail:
Created Date:  1995-02-08     Completed Date:  1995-02-08     Revised Date:  2009-11-11    
Medline Journal Info:
Nlm Unique ID:  0047142     Medline TA:  Respir Physiol     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  27-41     Citation Subset:  IM    
Department of Physiology, Dartmouth Medical School, Lebanon, NH 03756.
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MeSH Terms
Brain / enzymology
Carbon Dioxide / blood*
Carbonic Anhydrase Inhibitors / pharmacology
Carbonic Anhydrases / metabolism*
Chemoreceptor Cells / physiology*
Extracellular Space / enzymology
Ganglia, Invertebrate / enzymology
Helix (Snails) / metabolism*
Hemolymph / enzymology
Hypercapnia / enzymology,  metabolism
Grant Support
Reg. No./Substance:
0/Carbonic Anhydrase Inhibitors; 124-38-9/Carbon Dioxide; EC Anhydrases

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