Abstract
The pyridine nucleotides from both the epithelium and the endothelium of rabbit cornea were measured by the cycling assay. Sodium azide (10 m m) applied for 1 hr to induce histotoxic anoxia decreased the endothelial NAD + NADH ratio from 4·62 to 1·49 and decreased the epithelial NAD + NADH ratio from 2·56 to 1·08. The larger NAD + NADH ratio for the endothelium as compared to the epithelium corresponds to a more oxidized state. The corresponding ratios for NADP + NADPH were 1·2 for the endothelium and 0·70 for the epithelium. Sodium azide had no effect on the NADP + NADPH ratio for the endothelium, but decreased the epithelial ratio to 0·62. Pyridine nucleotide fluorescence was measured with a difference corneal fluorometer on the perfused whole cornea preparation and the perfused everted corneal preparation. Sodium azide (10 m m) for 30 min resulted in a 19·4 ± 0·7% increase in the pyridine nucleotide fluorescence from the whole corneal preparation and a 4·5 ± 0·6% increase from the everted endothelial preparation. Corneal anoxia induced by stopping the perfusion on the endothelial side resulted in a 18·7 ± 0·6% increase in pyridine nucleotide fluorescence for the whole corneal preparation. Sodium azide (10 m m) resulted in a 35% decrease in the transendothelial potential difference and a 76% decrease in the rate of transendothelial fluid transport. A comparison is made between invasive chemical analysis and real time, non-invasive fluorometry to measure histotoxic corneal anoxia.
Published Version
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