Osmoregulatory alterations in myo-inositol uptake by bovine lens epithelial cells. III. Effects of cycloheximide and colchicine on Na+-myo-inositol cotransporter activity under hypertonic conditions, inhibition of a plasma membrane osmotic stress protein

Patrick R. Cammarata, Hai Qing Chen, Cheng Zhou, Rustin Reeves

Research output: Contribution to journalArticle

4 Scopus citations

Abstract

Cultured bovine lens epithelial cells adapt to hypertonic sodium stress via an increase in Na+-myo-inositol cotransporter activity and accumulate myo-inositol. At least 12 hr of hypertonic exposure was necessary to enhance myo-inositol accumulation; and thereafter, uptake activity continued to increase throughout the duration of a 72-hr exposure period. Switching from hypertonic to isotonic medium for 24 hr reversed the otherwise elevated accumulation activity. The protein synthesis inhibitor, cycloheximide, did not affect myo-inositol uptake in isotonic medium but markedly decreased myo-inositol uptake in hypertonic medium. Cells exposed to hypertonic conditions and the microtubule disrupter, colchicine, similarly showed marked impairment of the otherwise enhanced myo-inositol uptake. These studies indicated that hypertonicity-induced elevation of Na+-myo-inositol cotransporter activity in cultured bovine lens epithelial cells is not solely attributed to the increased sodium gradient alone, but rather involves increased de novo synthesis of the Na+-myo-inositol cotransporter protein(s).

Original languageEnglish
Pages (from-to)83-90
Number of pages8
JournalExperimental eye research
Volume59
Issue number1
DOIs
StatePublished - Jul 1994

Keywords

  • Cultured lens epithelial cells
  • Hypertonicity
  • Na-myo-inositol cotransport protein(s)
  • Osmoregulation
  • Protein synthesis

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