Effect of fatty acids on isolated ovine pancreatic islets

A procedure was developed for the isolation of intact islets of Langerhans from sheep pancreas. The pancreas was disrupted by syringe injection of Hanks solution followed by collagenase incubation and islet separation by sedimentation. The islets were incubated in varying concentrations of glucose and butyrate. The rate of insulin release was approximately linear while the glucose and butyrate concentrations were increased. In additional studies at 2.5 and 5.0 mM levels of substrate concentration, the stimulation of insulin had the following pattern: octanoate greater than hexanoate greater than butyrate, whereas beta-hydroxybutyrate, lactate, acetate, and propionate had only slight stimulatory effects that were not statistically significant. Decanoate did not alter insulin release from isolated islets. These data confirm earlier in vivo reports that fatty acids stimulate pancreatic hormone release in sheep and that the stimulus is related to chain length of the fatty acid through C-8 but that C-10 has no effect. A hypothesis was suggested to explain these results based on chain length, solubility, and plasma membrane alterations.