The effect of cycloheximide on rubidium fluxes in the cultured bovine lens

Abstract

Background: Changes in lens electrolyte balance and hydration are considered to play a significant role in the aetiology of cataract. However, the reasons for these changes are not understood. The purpose of this study was to examine the requirement of protein synthesis for maintenance of electrolyte balance in the lens.

Methods: Whole adult bovine lenses were incubated for up to five days in the presence and absence of 0.4 mM cycloheximide. The uptake and subsequent efflux of [86]Rb was measured before and after exposure of the lenses to ouabain.

Results: Incubation with cycloheximide for 23 hours did not affect [86] Rb uptake in the cultured bovine lens. However, exposure to cycloheximide for five days reduced the ability of the lens to accumulate [86] Rb by 69 per cent. This is similar to the 65 to 75 per cent reduction, which was obtained when lenses maintained in culture for zero or five days were incubated with ouabain. Ouabain and cycloheximide did not affect efflux rates for the [86] Rb after 23 hours. Exposure to cycloheximide for five days resulted in a three‐fold increase in efflux rate relative to the control lenses. Subsequent exposure of the five‐day control lenses to ouabain produced a similar increase.

Conclusions: The data are consistent with the notion that continued protein synthesis is required for the maintenance of normal electrolyte balance in the lens.

Key words:

• cycloheximide
• lens
• Na
• K‐ATPase
• ouabain
• protein synthesis