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Manipulating rat lens glucose metabolism with exogenous substrates
H M Cheng1, F Y Cheng, G H Tanaka
1Howe Laboratory of Ophthalmology, Harvard Medical School, Boston, MA, USA.
Experimental Eye Research
|October 1, 1995
Summary
Mannose and pyruvate show promise in managing diabetic cataracts. Mannose preserves lens metabolites, while pyruvate reduces sorbitol production and enhances energy metabolism in diabetic rat lenses.
Area of Science:
- Biochemistry
- Ophthalmology
- Diabetic Complications
Background:
- Diabetic lens metabolism is altered by exogenous substrates.
- Diabetic cataract is a significant complication of diabetes.
- Polyol formation contributes to diabetic cataract development.
Purpose of the Study:
- To investigate the effects of mannose and pyruvate on diabetic lens metabolism in vivo.
- To assess the potential of these substrates in preventing or mitigating diabetic cataract formation.
Main Methods:
- In vivo and in vitro studies using rat lenses.
- Analysis of 31P metabolites using Nuclear Magnetic Resonance (NMR).
- Measurement of oxygen consumption and polyol (sorbitol) levels.
Main Results:
- Mannose, a glucose epimer, did not form polyols and preserved 31P membrane metabolites in diabetic rat lenses.
- Pyruvate reduced sorbitol accumulation by 50% in glucose-incubated lenses and altered lens metabolism.
- Pyruvate pre-treatment affected oxygen consumption, indicating alanine dehydrogenase activation and Krebs cycle saturation.
Conclusions:
- Dietary mannose may preserve lens metabolites, aiding in diabetic cataract management alongside hypoglycemic therapy.
- Pyruvate shows potential in enhancing lens energy metabolism and reducing sorbitol production in diabetic conditions.