Epithelial activity of hexokinase and glucose-6-phosphate dehydrogenase in cultured bovine lenses recovering from pharmaceutical-induced optical damage.
OBJECTIVE
In a previous toxicological study, cultured bovine lenses exposed to three topical anesthetics displayed distinct patterns of optical damage and recovery. This work investigated the epithelial activity of the metabolic enzymes hexokinase (HK) and glucose-6-phosphate dehydrogenase (G6PD) in lenses recovering from anesthetic-induced damage.


METHODS
Cultured bovine lenses were exposed to the anesthetics Alcaine, Fluress and Fluoracaine for 2 h. An automated laser scanner was used to determine the focal length variability (FLV) of the lenses at time-points up to 24 h following their return to fresh culture medium. The epithelial enzyme activities for HK and G6PD were then assayed at the 24 h time-point.


RESULTS
Lenses exposed to Alcaine displayed an abrupt increase in FLV, while Fluoracaine treated lenses exhibited optical damage at a slower rate. The FLV in these two groups recovered to near-control levels after 24 h. Fluress treated lenses did not differ in FLV from controls at any time. The activities of both HK and G6PD were significantly reduced in epithelial samples from each of the three anesthetic treatment groups, relative to controls.


CONCLUSIONS
These results show that lens optical quality can recover despite a severe reduction in epithelial HK and G6PD activity, indicating that the optical function of the lens may not be directly related to epithelial metabolic activity. The ScanTox In Vitro Assay System provides an objective measure of lens optical quality, enabling a direct comparison of optical damage and recovery to lens biochemical changes.
Hartwick
Andrew T E
AT
School of Optometry, University of Waterloo, Waterloo, Ontario, Canada.
Sivak
Jacob G
JG
D000779:Anesthetics, Local / Q000633:toxicity*; D000818:Animals; D002417:Cattle; D002724:Chlorobutanol / Q000633:toxicity; D003470:Culture Media; D004338:Drug Combinations; D004492:Edetic Acid / Q000633:toxicity; D004847:Epithelial Cells / Q000201:enzymology*; D019793:Fluorescein; D005452:Fluoresceins / Q000633:toxicity; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism*; D006593:Hexokinase / Q000378:metabolism*; D007908:Lens, Crystalline / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D009924:Organ Culture Techniques; D011205:Povidone / Q000633:toxicity; D011310:Preservatives, Pharmaceutical; D011343:Procaine / Q000031:analogs & derivatives* / Q000633:toxicity; D011430:Propoxycaine / Q000633:toxicity
D000779:Anesthetics, Local; D003470:Culture Media; D004338:Drug Combinations; D005452:Fluoresceins; D011310:Preservatives, Pharmaceutical; C010961:Fluress; D011343:Procaine; D004492:Edetic Acid; C005717:proxymetacaine; D005954:Glucosephosphate Dehydrogenase; D006593:Hexokinase; D011430:Propoxycaine; D011205:Povidone; D002724:Chlorobutanol; D019793:Fluorescein