Messenger RNA from intact rat pancreatic islets, or from transformed hamster beta (HIT) cells, hybridized with the cDNA probe for type I (but not type II) phospholipase A2. The levels of phospholipase A2 mRNA increased in islets from fasted rats: they decreased in islets cultured in a high glucose concentration (control values at 5.5 mM glucose = 150±6% of those at 22 mM) which impaired subsequent insulin secretion (reduction in second-phase release = 70±11%). These studies uniquely demonstrate that type I phospholipase A2 is expressed specifically in beta cells and that nutrient availability modulates transcript levels, an effect which could contribute to the detrimental influence of prolonged hyperglycemia on islet function.
- Beta cell
- Pancreatic islet