Abstract
In order to explore a role of lipid metabolism in islet β-cell functions, we examined the effect of oleic acid (OA) treatment on insulin secretion and electrical properties of islet β-cells. Islets isolated from rat pancreas were exposed with 0.1 mM OA for 3 days. The amount of protein in OA-treated islets was similar to that of OA-untreated (control) islets. On the other hand, the amount of insulin in OA-treated islets was lower than that in control islets. Insulin secretion from OA-treated islets exposed to a low (2.8 mM) glucose was slightly higher than that from control islets. On the other hand, in OA-treated islets an elevation of glucose concentration (16.7 mM) did not increase insulin secretion, whilst it significantly increased in control islets. In the low glucose condition, β-cells isolated from control islets were silent with ATP-sensitive K+ channels (KATP) being open, whereas OA-treated β-cells showed spontaneous action potential firing with KATP mostly closed. Under a condition of null ATP inside the membrane, KATP activities of excised patches from control and OA-treated β-cells were similar. ATP sensitivity to KATP for OA-treated cells, however, was higher than that for control cells. These results suggest that treatment of islets with OA interferes the glucose responsiveness of β-cells by evoking electrical excitation even in a low glucose condition. [Jpn J Physiol 54 Suppl:S73 (2004)]
