Ascorbate in the Rat Lens: Dependence on Dietary Intake

Vol. 37, No. 3, 2005

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Original Paper

Ascorbate in the Rat Lens: Dependence on Dietary Intake
Vino C. Mody Jr.^a, Manoj Kakar^a, Åse Elfving^b, Per G. Söderberg^a, Stefan Löfgren^a

^aSt. Erik's Eye Hospital and
^bDepartment of Physiology and Pharmacology, Division of Pharmacology, Karolinska Institutet, Stockholm, Sweden

Address of Corresponding Author

Ophthalmic Res 2005;37:142-149 (DOI: 10.1159/000085534)

Key Words

Ascorbate
Rat lens

Abstract

Purpose: To establish a method for sample preparation to measure ascorbate in whole lenses and to investigate whether lens ascorbate concentration is dependent on dietary ascorbate intake. Methods: Four groups of 3 young Sprague-Dawley rats each were fed chow containing L-ascorbate, either 0.0, 5.7, 57.0 or 114.0 mmol/kg for a duration of 4 weeks. Thereafter, each rat was sacrificed. The lens was extracted, photographed, and lens wet weight was measured. The lens was homogenized in 1.0 ml of 0.25% metaphosphoric acid, the homogenate was centrifuged and the supernatant ultrafiltered. The filtrate was injected into an ion exchange, reversed-phase Polypore H HPLC column equipped with a 254-nm ultraviolet detector. Samples were calibrated against an L-ascorbate standard. Polynomial regression analysis was performed on the data. Results: All lenses were devoid of cataract. A 95% confidence interval for baseline content of ascorbate without any dietary intake was estimated to be 0.16 ± 0.01 µmol/g wet weight of lens. The lens ascorbate concentration increased linearly with dietary ascorbate intake with an increased rate, estimated as a 95% confidence interval of 0.33 ± 0.18 (µmol ascorbate) (g lens)^-1(mol ascorbate)^-1 (kg chow) with r² = 0.62. Conclusion: Lens ascorbate concentration linearly increases with dietary ascorbate intake without cataract development in the rat. The currently presented method for sample preparation to measure the whole-lens content of ascorbate is applicable.

Author Contacts

Vino C. Mody Jr.
Research Department, St. Erik's Eye Hospital, Karolinska Institutet
Polhemsgatan 50
SE-112 82 Stockholm (Sweden)
Tel. +46 8 672 3043, Fax +46 8 672 3352, E-Mail vino.mody@ste.ki.se

Article Information

Received: April 15, 2004
Accepted after revision: October 21, 2004
Published online: May 3, 2005
Number of Print Pages : 8
Number of Figures : 6, Number of Tables : 0, Number of References : 39

Medline Abstract (ID 15867476)

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