Studies on retinal blood flow regulation: the effect of PaCO2 on blood flow, oxygen availability, oxygen consumpsion rate and ERG in monkeys

Tsacopoulos, M.; Baker, Rex; Hamasaki, D.I.; David, Noble J.

doi:10.1016/0014-4835(73)90260-1

Cited by 4 publications

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“…However, acetazolamide attenuates the amplitudes of ERG responses. 51 Moreover, under hypercapnic conditions, the b-wave of ERG is depressed, 52,53 as a result of reduction in extracellular K ϩ . 54 In addition, recent studies have shown either no effect 55 or decreased contrast sensitivity 56,57 by CO 2 .…”

Section: Discussionmentioning

confidence: 99%

Effect of Carbogen Breathing and Acetazolamide on Optic Disc Po₂

Petropoulos

Pournaras

Cruz

et al. 2005

Invest. Ophthalmol. Vis. Sci.

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Section: Discussionmentioning

confidence: 99%

Effect of Carbogen Breathing and Acetazolamide on Optic Disc Po₂

Petropoulos

Pournaras

Cruz

et al. 2005

Invest. Ophthalmol. Vis. Sci.

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“…Nonetheless, it has been proven that acetazolamide attenuates the amplitudes of ERG responses [9]. Moreover, under hypercapnic conditions, the b-wave of ERG is depressed [16,25] due to a decrease in extracellular K + [19]. In addition, recent studies have shown either no effect [10] or a decrease in contrast sensitivity [12] by CO 2 .…”

Section: Discussionmentioning

confidence: 99%

Effect of Acetazolamide on the Optic Disc Oxygenation in Miniature Pigs

2004

Klin Monatsbl Augenheilkd

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Systemic hyperoxia alone is not sufficient to increase substantially the optic disc PO (2) in miniature pigs due to a vasoconstrictor effect. Intravenous injection of acetazolamide can increase the optic disc PO (2) progressively, due to a vasodilatory effect of elevated systemic PaCO (2). The association of acetazolamide injection with systemic hyperoxia can further improve the oxygenation of the optic disc.

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“…However, increased oxygenation of the ONH through hypercapnia does not necessarily guarantee beneficial functional effect for a patient. In fact, under hypercapnic conditions the b-wave of the ERG is depressed [44,45], and recent studies have shown either no effect [46] or a decrease in contrast sensitivity [47] by CO 2 . Careful clinical interpretation of experimental results regarding the ONH function is mandatory.…”

Section: Discussionmentioning

confidence: 99%

Effect of Indomethacin on the Hypercapnia-Associated Vasodilation of the Optic Nerve Head Vessels: An Experimental Study in Miniature Pigs

Petropoulos¹,

Pournaras²

2005

Ophthalmic Res

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Purpose: To evaluate whether prostaglandins are mediators of the hypercapnia-associated vasodilation of the optic nerve head vessels. Methods: We measured the PO₂ at intervascular areas of the optic disc in 9 anaesthetized miniature pigs using oxygen-sensitive microelectrodes placed at <50 µm from the optic disc. PO₂ was measured continuously under normoxia, hyperoxia (breathing of 100% O₂), carbogen breathing (95% O₂, 5% CO₂), and hypercapnia (40% increase in inhaled CO₂). Similar measurements under these conditions were also done after intravenous administration of the prostaglandin inhibitor indomethacin. Results: Before the injection of indomethacin, we observed a slight increase in the optic disc PO₂ during hypercapnia (ΔPO₂ = 2.0 ± 1.7 mm Hg; p < 0.001; n = 18) or hyperoxia (ΔPO₂ = 3.4 ± 1.6 mm Hg; p < 0.001; n = 23), but a much more important increase during carbogen breathing (ΔPO₂ = 12.0 ± 5.1 mm Hg; p < 0.001; n = 23). After the injection of indomethacin, the increase in the optic disc PO₂ was similar during hyperoxia (ΔPO₂ = 5.6 ± 2.2 mm Hg; p < 0.001; n = 9) or carbogen breathing (ΔPO₂ = 5.8 ± 3.2 mm Hg; p < 0.001; n = 9), while in hypercapnia the variation of the optic disc PO₂ was minimal (ΔPO₂ = 0.5 ± 1.9 mm Hg; p > 0.1; n = 6). Conclusions: Indomethacin inhibits the vasodilatory effect of increased systemic PaCO₂ on the optic nerve head vessels, leading to a similar moderate increase in the optic disc PO₂ during carbogen breathing as in hyperoxia. Indomethacin also inhibits the increase in the optic disc PO₂ seen during hypercapnia. Those results indicate that prostaglandins are mediators of the hypercapnia-associated vasodilation of the optic nerve head vessels.

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Studies on retinal blood flow regulation: the effect of PaCO2 on blood flow, oxygen availability, oxygen consumpsion rate and ERG in monkeys

Cited by 4 publications

References 0 publications

Effect of Carbogen Breathing and Acetazolamide on Optic Disc Po₂

Effect of Carbogen Breathing and Acetazolamide on Optic Disc Po₂

Effect of Acetazolamide on the Optic Disc Oxygenation in Miniature Pigs

Effect of Indomethacin on the Hypercapnia-Associated Vasodilation of the Optic Nerve Head Vessels: An Experimental Study in Miniature Pigs

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Studies on retinal blood flow regulation: the effect of PaCO2 on blood flow, oxygen availability, oxygen consumpsion rate and ERG in monkeys

Cited by 4 publications

References 0 publications

Effect of Carbogen Breathing and Acetazolamide on Optic Disc Po2

Effect of Carbogen Breathing and Acetazolamide on Optic Disc Po2

Effect of Acetazolamide on the Optic Disc Oxygenation in Miniature Pigs

Effect of Indomethacin on the Hypercapnia-Associated Vasodilation of the Optic Nerve Head Vessels: An Experimental Study in Miniature Pigs

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Effect of Carbogen Breathing and Acetazolamide on Optic Disc Po₂

Effect of Carbogen Breathing and Acetazolamide on Optic Disc Po₂