Optic nerve pH and PO2: the effects of carbonic anhydrase inhibition, and metabolic and respiratory acidosis

2.50
Hdl Handle:
http://hdl.handle.net/2336/20333
Title:
Optic nerve pH and PO2: the effects of carbonic anhydrase inhibition, and metabolic and respiratory acidosis
Authors:
Pedersen, Daniella B; Stefansson, Einar; Kiilgaard, Jens F; Jensen, Peter K; Eysteinsson, Thor; Bang, Kurt; la Cour, Morten
Citation:
Acta Ophthalmol Scand. 2006, 84(4):475-80
Issue Date:
1-Aug-2006
Abstract:
PURPOSE: Earlier studies have demonstrated that carbonic anhydrase inhibitors (CAIs) increase optic nerve oxygen tension (ONPO(2)) in pigs. We hypothesized that the mechanism of this effect was either a CO(2) increase or a pH decrease in tissue and blood. To test this hypothesis we investigated and compared how optic nerve pH (ONpH) and ONPO(2) are affected by: (1) carbonic anhydrase inhibition; (2) respiratory acidosis, and (3) metabolic acidosis. We measured ONpH with a glass pH electrode and ONPO(2) with a polarographic oxygen electrode. One of the electrodes was placed in the vitreous cavity 0.5 mm over the optic nerve in the eyes of domestic pigs. METHODS: We measured ONpH during carbonic anhydrase inhibition and ONpH or ONPO(2) during NH(4)Cl-induced metabolic acidosis and during CO(2) breathing (respiratory acidosis). RESULTS: Baseline ONpH was 0.12 +/- 0.06 lower than arterial pH (mean +/- SD, n = 10, p < 0.001). Optic nerve pH decreased with arterial pH during carbonic anhydrase inhibition, metabolic and respiratory acidosis. Optic nerve oxygen tension was not affected by metabolic acidosis but increased during CO(2) breathing, as it has been shown to do during carbonic anhydrase inhibition. CONCLUSIONS: There is a close correlation between arterial blood pH and intraocular pH. Isolated ONpH changes do not affect ONPO(2), thus the ONPO(2) increase seen with carbonic anhydrase inhibition is probably not only due to pH changes in the blood and optic nerve. Accumulation of CO(2), either alone or in combination with a pH change, is likely to cause the ONPO(2) increase, but a direct vascular effect should also be considered.
Description:
To access publisher full text version of this article. Please click on the hyperlink in Additional Links field
Additional Links:
http://www.blackwell-synergy.com/doi/abs/10.1111/j.1600-0420.2006.00709.x

Full metadata record

DC FieldValue Language
dc.contributor.authorPedersen, Daniella B-
dc.contributor.authorStefansson, Einar-
dc.contributor.authorKiilgaard, Jens F-
dc.contributor.authorJensen, Peter K-
dc.contributor.authorEysteinsson, Thor-
dc.contributor.authorBang, Kurt-
dc.contributor.authorla Cour, Morten-
dc.date.accessioned2008-03-11T15:10:44Z-
dc.date.available2008-03-11T15:10:44Z-
dc.date.issued2006-08-01-
dc.date.submitted2008-03-11-
dc.identifier.citationActa Ophthalmol Scand. 2006, 84(4):475-80en
dc.identifier.issn1395-3907-
dc.identifier.pmid16879567-
dc.identifier.doi10.1111/j.1600-0420.2006.00709.x-
dc.identifier.urihttp://hdl.handle.net/2336/20333-
dc.descriptionTo access publisher full text version of this article. Please click on the hyperlink in Additional Links fielden
dc.description.abstractPURPOSE: Earlier studies have demonstrated that carbonic anhydrase inhibitors (CAIs) increase optic nerve oxygen tension (ONPO(2)) in pigs. We hypothesized that the mechanism of this effect was either a CO(2) increase or a pH decrease in tissue and blood. To test this hypothesis we investigated and compared how optic nerve pH (ONpH) and ONPO(2) are affected by: (1) carbonic anhydrase inhibition; (2) respiratory acidosis, and (3) metabolic acidosis. We measured ONpH with a glass pH electrode and ONPO(2) with a polarographic oxygen electrode. One of the electrodes was placed in the vitreous cavity 0.5 mm over the optic nerve in the eyes of domestic pigs. METHODS: We measured ONpH during carbonic anhydrase inhibition and ONpH or ONPO(2) during NH(4)Cl-induced metabolic acidosis and during CO(2) breathing (respiratory acidosis). RESULTS: Baseline ONpH was 0.12 +/- 0.06 lower than arterial pH (mean +/- SD, n = 10, p < 0.001). Optic nerve pH decreased with arterial pH during carbonic anhydrase inhibition, metabolic and respiratory acidosis. Optic nerve oxygen tension was not affected by metabolic acidosis but increased during CO(2) breathing, as it has been shown to do during carbonic anhydrase inhibition. CONCLUSIONS: There is a close correlation between arterial blood pH and intraocular pH. Isolated ONpH changes do not affect ONPO(2), thus the ONPO(2) increase seen with carbonic anhydrase inhibition is probably not only due to pH changes in the blood and optic nerve. Accumulation of CO(2), either alone or in combination with a pH change, is likely to cause the ONPO(2) increase, but a direct vascular effect should also be considered.en
dc.language.isoenen
dc.publisherBlackwellen
dc.relation.urlhttp://www.blackwell-synergy.com/doi/abs/10.1111/j.1600-0420.2006.00709.xen
dc.subject.meshAcidosis, Respiratoryen
dc.subject.meshAmmonium Chlorideen
dc.subject.meshAnimalsen
dc.subject.meshCarbonic Anhydrase Inhibitorsen
dc.subject.meshCarbonic Anhydrasesen
dc.subject.meshHydrogen-Ion Concentrationen
dc.subject.meshIon-Selective Electrodesen
dc.subject.meshOptic Disken
dc.subject.meshOptic Nerveen
dc.subject.meshOxygenen
dc.subject.meshOxygen Consumptionen
dc.subject.meshPartial Pressureen
dc.subject.meshPolarographyen
dc.subject.meshSulfonamidesen
dc.subject.meshSwineen
dc.subject.meshThiophenesen
dc.titleOptic nerve pH and PO2: the effects of carbonic anhydrase inhibition, and metabolic and respiratory acidosisen
dc.typeArticleen
dc.contributor.departmentDepartment of Ophthalmology, Rigshospitalet, Copenhagen, Denmark. daniella@dadlnet.dken
dc.identifier.journalActa ophthalmologica Scandinavicaen

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