Effect of low temperatures on the metabolism of corneal cultures

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