Effects of enflurane on release of insulin by pancreatic islets in vitro

The effects of enflurane upon rate of insulin release from rat pancreatic islets were determined in vitro. A dose-related inhibitory effect of enflurane on glucose-stimulated insulin release was observed with almost complete inhibition being seen when the enflurane concentration in the gas phase was 3.21% (v/v), equivalent to 1.26 mM enflurane in the liquid phase. The onset on enflurane-induced inhibition was rapid, being fully developed within 5 minutes of islet exposure to the agent while the effect was equally rapidly reversed on removal of enflurane from the medium. As glucose metabolism is known to be required for glucose-stimulated insulin secretion to occur, rates of islet metabolism of [U-14C] glucose to 14CO2 were examined but these were unaffected by concentrations of enflurane up to 2.21 mM. To investigate further the metabolic integrity of islets, rates of islet incorporation of L-[4,5-3H] leucine were determined; these too were not significantly altered by concentrations of enflurane up to 1.26 mM. It is concluded that enflurane in the concentration range used clinically leads to a rapid, reversible inhibition of rat pancreatic islet insulin release, which is not attributable to interference with islet glucose metabolism or protein biosynthesis.