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Effect of increased oxygen tension on flicker-induced vasodilatation in the human retina.

Palkovits S, Told R, Boltz A, Schmidl D, Popa Cherecheanu A, Schmetterer L, Garhöfer G - J. Cereb. Blood Flow Metab. (2014)

Bottom Line: Breathing of C/O led to a decrease in arterial (-9.0±6.9%) and venous (-11.3±5.9%) vessel calibers.Flicker response was increased to 5.7±2.5% in arteries and to 8.6±4.1% in veins.The mechanism by which oxygen modulates the hyperemic response to FL stimulation remains to be elucidated.

View Article: PubMed Central - PubMed

Affiliation: Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.

ABSTRACT
In the retina, blood flow and neural activity are tightly coupled. Stimulation of the retina with flickering light is accompanied by an increase in blood flow. The current study seeks to investigate whether an increase in oxygen tension modulates flicker (FL)-induced vasodilatation in the human retina. A total of 52 healthy volunteers were included. Via a breathing mask, 100% oxygen (O(2)) was administered in one, a mixture of 8% carbon dioxide and 92% oxygen (C/O) in a second cohort. Retinal vessel diameters were measured with a Vessel Analyzer and FL responses were assessed before and during the breathing periods. At baseline, FL stimulation increased retinal vessel diameters by +3.7±2.3% in arteries and by +5.1±3.7% in veins. Breathing of C/O led to a decrease in arterial (-9.0±6.9%) and venous (-11.3±5.9%) vessel calibers. Flicker response was increased to 5.7±2.5% in arteries and to 8.6±4.1% in veins. Breathing of pure O2 induced a vasoconstriction of vessel diameters by -14.0±5.3% in arteries and -18.4±7.0% in veins and increased FL responses in arteries (+6.2±2.8%) and veins (+7.2±3.1%). Systemic hyperoxia increases FL-induced retinal vasodilatation in the retina. The mechanism by which oxygen modulates the hyperemic response to FL stimulation remains to be elucidated.

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Retinal vessel diameters at BL and during inhalation of the O2/CO2 mixture (left) and pure O2 (right). Data presented as mean and standard deviation. Asterisks mark significant differences. BL, baseline; BP, breathing period.
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fig1: Retinal vessel diameters at BL and during inhalation of the O2/CO2 mixture (left) and pure O2 (right). Data presented as mean and standard deviation. Asterisks mark significant differences. BL, baseline; BP, breathing period.

Mentions: In the O2 group, FL-induced vasodilatation was 3.5±2.5% in retinal arteries and 4.2±2.3% in retinal veins at BL conditions (both P<0.01). Inhalation of pure oxygen increased pO2 from 88±8 mm Hg to 364±100 mm Hg (P<0.01). Likewise, oxygen saturation increased from 97.5±0.9% to 99.0±0.4% (P<0.01) during the O2 breathing period and pCO2 decreased from 37.5±3.7 mm Hg to 33.8±7.8 mm Hg (P<0.01). In addition, pure oxygen breathing induced a vasoconstriction of retinal vessel diameters by −14.0±5.3% (see Figure 1, P<0.01) in retinal arteries and by −18.4±7.0% in retinal veins (P<0.01). During inhalation of oxygen FL-evoked vasodilatation was significantly higher compared with BL conditions in both retinal arteries (+6.2±2.8%, P<0.01) and retinal veins (+7.2±3.1%, P<0.05) (see Figure 2).


Effect of increased oxygen tension on flicker-induced vasodilatation in the human retina.

Palkovits S, Told R, Boltz A, Schmidl D, Popa Cherecheanu A, Schmetterer L, Garhöfer G - J. Cereb. Blood Flow Metab. (2014)

Retinal vessel diameters at BL and during inhalation of the O2/CO2 mixture (left) and pure O2 (right). Data presented as mean and standard deviation. Asterisks mark significant differences. BL, baseline; BP, breathing period.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4269745&req=5

fig1: Retinal vessel diameters at BL and during inhalation of the O2/CO2 mixture (left) and pure O2 (right). Data presented as mean and standard deviation. Asterisks mark significant differences. BL, baseline; BP, breathing period.
Mentions: In the O2 group, FL-induced vasodilatation was 3.5±2.5% in retinal arteries and 4.2±2.3% in retinal veins at BL conditions (both P<0.01). Inhalation of pure oxygen increased pO2 from 88±8 mm Hg to 364±100 mm Hg (P<0.01). Likewise, oxygen saturation increased from 97.5±0.9% to 99.0±0.4% (P<0.01) during the O2 breathing period and pCO2 decreased from 37.5±3.7 mm Hg to 33.8±7.8 mm Hg (P<0.01). In addition, pure oxygen breathing induced a vasoconstriction of retinal vessel diameters by −14.0±5.3% (see Figure 1, P<0.01) in retinal arteries and by −18.4±7.0% in retinal veins (P<0.01). During inhalation of oxygen FL-evoked vasodilatation was significantly higher compared with BL conditions in both retinal arteries (+6.2±2.8%, P<0.01) and retinal veins (+7.2±3.1%, P<0.05) (see Figure 2).

Bottom Line: Breathing of C/O led to a decrease in arterial (-9.0±6.9%) and venous (-11.3±5.9%) vessel calibers.Flicker response was increased to 5.7±2.5% in arteries and to 8.6±4.1% in veins.The mechanism by which oxygen modulates the hyperemic response to FL stimulation remains to be elucidated.

View Article: PubMed Central - PubMed

Affiliation: Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.

ABSTRACT
In the retina, blood flow and neural activity are tightly coupled. Stimulation of the retina with flickering light is accompanied by an increase in blood flow. The current study seeks to investigate whether an increase in oxygen tension modulates flicker (FL)-induced vasodilatation in the human retina. A total of 52 healthy volunteers were included. Via a breathing mask, 100% oxygen (O(2)) was administered in one, a mixture of 8% carbon dioxide and 92% oxygen (C/O) in a second cohort. Retinal vessel diameters were measured with a Vessel Analyzer and FL responses were assessed before and during the breathing periods. At baseline, FL stimulation increased retinal vessel diameters by +3.7±2.3% in arteries and by +5.1±3.7% in veins. Breathing of C/O led to a decrease in arterial (-9.0±6.9%) and venous (-11.3±5.9%) vessel calibers. Flicker response was increased to 5.7±2.5% in arteries and to 8.6±4.1% in veins. Breathing of pure O2 induced a vasoconstriction of vessel diameters by -14.0±5.3% in arteries and -18.4±7.0% in veins and increased FL responses in arteries (+6.2±2.8%) and veins (+7.2±3.1%). Systemic hyperoxia increases FL-induced retinal vasodilatation in the retina. The mechanism by which oxygen modulates the hyperemic response to FL stimulation remains to be elucidated.

Show MeSH
Related in: MedlinePlus