Temporal and regional production of 12(S)hydroxyeicosatetraenoic acid [12(S)-HETE] in rat lens.

Enzymatic production of 12(S)-hydroxyeicosatetraenoic acid [12(S)-HETE] from exogenous arachidonic acid (AA) was studied in the 9000 g supernatant fraction of either whole rat lens or the capsule-epithelium and cortex-nucleus regions with age (4-180 days). Whole rat lens 12(S)-HETE synthetic capacity measured either by RIA or HPLC was significantly decreased with lens growth. 12(S)-HETE production was highest in the 4-day-old rat lens, the earliest time point measured, and declined to background levels by 6 months of age. Regional studies demonstrated that the capsule-epithelium possessed a higher specific activity in comparison to the cortex-nucleus. However, lipoxygenase activity decreased significantly faster in the capsule-epithelium compared to the cortex-nucleus. The bulk of the 12-lipoxygenase activity was located in the cortex-nucleus due to the higher amount of tissue in the region. The elevated lipoxygenase activity in the neonate and its rapid decline with growth suggests that the enzyme may contribute in transforming the epithelial cells to fiber cells.