{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,3]],"date-time":"2026-06-03T18:25:18Z","timestamp":1780511118633,"version":"3.54.1"},"reference-count":54,"publisher":"The Company of Biologists","issue":"19","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2005,10,1]]},"abstract":"<jats:title>SUMMARY<\/jats:title><jats:p>Experiments were performed on bimodally breathing African lungfish Protopterus dolloi to examine the effects of inhibition of extracellular vs total (extracellular and intracellular) carbonic anhydrase (CA) activity on pulmonary and branchial\/cutaneous gas transfer. In contrast to previous studies on Protopterus, which showed that the vast majority of CO2 is excreted into the water through the gill and\/or skin whereas O2 uptake largely occurs via the lung, P. dolloi appeared to use the lung for the bulk of both O2uptake (91.0\u00b12.9%) and CO2 excretion (76.0\u00b16.6%). In support of the lung as the more important site of CO2 transfer,aerial hypercapnia (PCO2=40 mmHg) caused a significant rise in partial pressure of arterial blood CO2(PaCO2) whereas a similar degree of aquatic hypercapnia was without effect on PaCO2. Intravascular injection of low levels (1.2 mg kg-1) of the slowly permanent CA inhibitor, benzolamide, was without effect on red blood cell CA activity after 30 min, thus confirming its suitability as a short-term selective inhibitor of extracellular CA. Benzolamide treatment did not affect CO2 excretion, blood acid\u2013base status or any other measured variable within the 30 min measurement period. Injection of the permeant CA inhibitor acetazolamide (30 mg kg-1) resulted in the complete inhibition of red cell CA activity within 10 min. However, CO2excretion (measured for 2 h after injection) and arterial blood acid\u2013base status (assessed for 24 h after injection) were unaffected by acetazolamide treatment. Intra-arterial injection of bovine CA (2 mg kg-1) caused a significant increase in overall CO2excretion (from 0.41\u00b10.03 to 0.58\u00b10.03 mmol kg-1h-1) and an increase in air breathing frequency (from 19.0\u00b11.3 to 24.7\u00b11.8 breaths min-1) that was accompanied by a slight, but significant, reduction in PaCO2 (from 21.6\u00b11.6 to 19.6\u00b11.8 mmHg).<\/jats:p><jats:p>The findings of this study are significant because they (i) demonstrate that, unlike in other species of African lungfish that have been examined, the gill\/skin is not the major route of CO2 excretion in P. dolloi, and (ii) suggest that CO2 excretion in Protopterus may be less reliant on carbonic anhydrase than in most other fish species.<\/jats:p>","DOI":"10.1242\/jeb.01780","type":"journal-article","created":{"date-parts":[[2005,9,16]],"date-time":"2005-09-16T18:02:58Z","timestamp":1126893778000},"page":"3805-3815","source":"Crossref","is-referenced-by-count":45,"title":["An investigation of the role of carbonic anhydrase in aquatic and aerial gas transfer in the African lungfish<i>Protopterus dolloi<\/i>"],"prefix":"10.1242","volume":"208","author":[{"given":"S. F.","family":"Perry1","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"K. M.","family":"Gilmour","sequence":"additional","affiliation":[{"name":"Department of Biology, University of Ottawa, 150 Louis Pasteur, Ottawa, ON K1N 6N5, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"E. R.","family":"Swenson","sequence":"additional","affiliation":[{"name":"Veterans Affairs Puget Sound Health Care System, 1660 South Columbian Way Seattle, WA 98108, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"B.","family":"Vulesevic","sequence":"additional","affiliation":[{"name":"Veterans Affairs Puget Sound Health Care System, 1660 South Columbian Way Seattle, WA 98108, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"S. F.","family":"Chew","sequence":"additional","affiliation":[{"name":"Department of Natural Sciences, National Institute of Education, Nanyang Technological University, Republic of Singapore"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Y. K.","family":"Ip","sequence":"additional","affiliation":[{"name":"Department of Biological Sciences, National University of Singapore,Republic of Singapore"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"237","reference":[{"key":"2021042510404361900_REF1","doi-asserted-by":"crossref","unstructured":"Amin-Naves, J., Giusti, H. and Glass, M. L.(2004). Effects of acute temperature changes on aerial and aquatic gas exchange, pulmonary ventilation and blood gas status in the South American lungfish, Lepidosiren paradoxa.Comp. Biochem. Physiol.138A,133-139.","DOI":"10.1016\/j.cbpb.2004.02.016"},{"key":"2021042510404361900_REF2","doi-asserted-by":"crossref","unstructured":"Axelsson, M. and Fritsche, R. (1994). 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