Effect of low temperatures on the metabolism of corneal cultures

Abstract

Whole pig corneas were stored in minimum essential medium at 4°, 21°, and 31° C in closed flasks with sufficient air. When the corneal cultures were kept at 31° C, the epithelial glucose remained below the levels of the stroma. At 21° C the glucose levels remained constant at the initial values, and at 4° C glucose accumulated in the epithelium. The concentration gradients for glucose between the stroma and epithelium were maintained in the natural direction only at 31° C. At 4° and 21° C, the concentration gradients for glucose were reversed in direction from the epithelium to the stroma. Lactate production in the epithelium was higher in the cultures at 31° C than at 21° C, and it was much lower at 4° C. The ATP levels and ATP/ADP ratios were highest at 21° C, although at 31° C the initially decreased ATP levels and ATP/ADP ratios recovered after 6 days of culture. The cultured corneas were markedly swollen. At 4° C, no hydration control was seen. At 21° and 31° C, significantly less swelling was observed. Consequently, at the lower temperatures membrane barriers and pump functions might have been impaired.