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Acute hyperglycemia-induced endothelial dysfunction in retinal arterioles in cats
Kenji Sogawa1, Taiji Nagaoka, Naohiro Izumi
1Department of Ophthalmology, Asahikawa Medical College, Asahikawa, Hokkaido, Japan.
Investigative Ophthalmology & Visual Science
|January 1, 2010
Summary
Acute hyperglycemia increases retinal blood flow (RBF) and may impair endothelial function, partly due to oxidative stress. Superoxide removal can prevent this dysfunction, suggesting a therapeutic target for diabetic retinopathy.
Area of Science:
- Ophthalmology
- Cardiovascular Physiology
- Endocrinology
Background:
- Diabetic retinopathy is a leading cause of blindness.
- Hyperglycemia is a key risk factor for diabetic complications.
- Understanding the impact of acute hyperglycemia on retinal microcirculation is crucial.
Purpose of the Study:
- To investigate acute hyperglycemia's effects on feline retinal microcirculation and endothelial function.
- To assess the role of superoxide in hyperglycemia-induced retinal endothelial dysfunction.
- To evaluate superoxide removal as a protective strategy.
Main Methods:
- Induced hyperglycemia (30 mM glucose) and controlled for osmolality (mannitol) in cats.
- Measured retinal blood flow (RBF) using laser Doppler velocimetry.
- Assessed endothelial function via bradykinin (BK) and sodium nitroprusside (SNP) administration; administered TEMPOL to scavenge superoxide.
Main Results:
- Acute hyperglycemia and mannitol increased RBF.
- Hyperglycemia impaired BK-induced vasodilation but not SNP-induced vasodilation.
- Hyperglycemia inhibited RBF recovery after hyperoxia; TEMPOL prevented this impairment.
Conclusions:
- Acute hyperglycemia increases RBF via osmolality and causes retinal endothelial dysfunction partly through oxidative stress.
- Superoxide contributes to hyperglycemia-induced retinal vascular dysfunction.
- Systemic hyperoxia can noninvasively assess retinal endothelial function during hyperglycemia.
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