HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 574/2/565    most recent jphysiol.2006.110528v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Teppema, L. J. Articles by Dahan, A. Search for Related Content PubMed PubMed Citation Articles by Teppema, L. J. Articles by Dahan, A. Related Collections Integrative

¹ Department of Anaesthesiology, Leiden University Medical Center, Leiden, the Netherlands

We compared the effects of the carbonic anhydrase inhibitors methazolamide and acetazolamide (3 mg kg^–1, I.V.) on the steady-state hypoxic ventilatory response in 10 anaesthetized cats. In five additional animals, we studied the effect of 3 and 33 mg kg^–1 methazolamide. The steady-state hypoxic ventilatory response was described by the exponential function:

where is the inspired ventilation_, G is hypoxic sensitivity, D is the shape factor and A is hyperoxic ventilation. In the first group of 10 animals, methazolamide did not change parameters G and D, while A increased from 0.86 ± 0.33 to 1.30 ± 0.40 l min^–1 (mean ± S.D., P = 0.003). However, the subsequent administration of acetazolamide reduced G by 44% (control, 1.93 ± 1.32; acetazolamide, 1.09 ± 0.92 l min^–1, P = 0.003), while A did not show a further change. Acetazolamide tended to reduce D (control, 0.20 ± 0.07; acetazolamide, 0.14 ± 0.06 kPa^–1, P = 0.023). In the second group of five animals, neither low- nor high-dose methazolamide changed parameters G, D and A. The observation that even high-dose methazolamide, causing full inhibition of carbonic anhydrase in all body tissues, did not reduce the hypoxic ventilatory response is reminiscent of previous findings by others showing no change in magnitude of the hypoxic response of the in vitro carotid body by this agent. This suggests that normal carbonic anhydrase activity is not necessary for a normal hypoxic ventilatory response to occur. The mechanism by which acetazolamide reduces the hypoxic ventilatory response needs further study.

accepted after revision 28 April 2006; first published online 4 May 2006)
Corresponding author L. J. Teppema: Department of Anesthesiolgy, Leiden University Medical Center, PO Box 9600, 2300 RC Leiden, the Netherlands. Email: l.j.s.m.teppema{at}lumc.nl

This article has been cited by other articles:

				D. E. Leaf and D. S. Goldfarb Mechanisms of action of acetazolamide in the prophylaxis and treatment of acute mountain sickness J Appl Physiol, April 1, 2007; 102(4): 1313 - 1322. [Abstract] [Full Text] [PDF]

				E. R. Swenson and L. J. Teppema Prevention of acute mountain sickness by acetazolamide: as yet an unfinished story J Appl Physiol, April 1, 2007; 102(4): 1305 - 1307. [Full Text] [PDF]