December 1992
Volume 33, Issue 13
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Articles  |   December 1992
Modulation of myo-[3H]inositol uptake by glucose and sorbitol in cultured bovine lens epithelial cells. II. Characterization of high- and low-affinity myo-inositol transport sites.
Author Affiliations
  • P R Cammarata
    Department of Anatomy and Cell Biology, Texas College of Osteopathic Medicine/University of North Texas, Fort Worth 76107.
  • H Q Chen
    Department of Anatomy and Cell Biology, Texas College of Osteopathic Medicine/University of North Texas, Fort Worth 76107.
  • J Yang
    Department of Anatomy and Cell Biology, Texas College of Osteopathic Medicine/University of North Texas, Fort Worth 76107.
  • T Yorio
    Department of Anatomy and Cell Biology, Texas College of Osteopathic Medicine/University of North Texas, Fort Worth 76107.
Investigative Ophthalmology & Visual Science December 1992, Vol.33, 3572-3580. doi:
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      P R Cammarata, H Q Chen, J Yang, T Yorio; Modulation of myo-[3H]inositol uptake by glucose and sorbitol in cultured bovine lens epithelial cells. II. Characterization of high- and low-affinity myo-inositol transport sites.. Invest. Ophthalmol. Vis. Sci. 1992;33(13):3572-3580.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Myo-[3H]inositol accumulation in cultured bovine lens epithelial cells (BLECs) occurred by high- and low-affinity, Na(+)-dependent transport sites. The high- and low-affinity transport systems had a Km of 27 +/- 4 and 157 +/- 22 mumol/l, respectively, and Vmax of 652 +/- 35 and 2952 +/- 308 pmol/mg protein/hr, respectively. The uptake of myo-[3H]inositol was lowered after chronic (20 hr) incubation of cultured cells in 40 mmol/l glucose throughout the concentration range for 1.5-400 mumol/l myo-inositol. The coadministration of sorbinil (0.1 mmol/l) to 40 mmol/l glucose partially prevented the inhibitory effect of glucose on myo-[3H]inositol uptake. Although the aldose reductase inhibitor prevented the inhibitory effect of glucose on the low-affinity transport site, a glucose-sensitive process for myo-[3H]inositol uptake on the high-affinity transport site was uncovered by Lineweaver-Burk analysis. Acute exposure (3 hr) of cultured BLECs maintained in physiologic medium (Eagle's minimal essential medium, 5.5 mmol/l glucose) to a range of 5.5-44 mmol/l glucose plus sorbinil also caused a decrease in myo-[3H]inositol uptake. Dixon plot analysis confirmed that the acute effect of glucose was the result of competitive inhibition of the high-affinity myo-inositol transport site. Acute exposure of cultured cells to 10-40 mmol/l sorbitol also diminished the accumulation of myo-[3H]inositol. Dixon plot analysis established that the acute effect of exogenous sorbitol was the result of competitive inhibition of the low-affinity myo-inositol transport site.(ABSTRACT TRUNCATED AT 250 WORDS)

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