Changes in membrane lipids of the beta-cell during insulin secretion.

The effect of insulin secretion on the turnover of phospholipids in the pancreatic beta-cell was determined by following the fate, during secretion, of phospholipids prelabelled with 3H-glycerol. The secretion of insulin in response to glucose (20mM) plus isobutyl-methylxanthine (0.5mM) was associated with a calcium dependent increase in the turnover of the major classes of phospholipids and an increase production of 1:2 diacylglycerol and triacylglycerol. In addition, changes in the fatty acid composition of the beta-cell, during insulin secretion, were determined. There was an increase in the proportion of unsaturated fatty acids relative to saturated fatty acids during stimulation by glucose (20mM) plus isobutylmethylxanthine (0.5mM). The results of this study suggest that there are marked changes in the phospholipid composition of the beta-cell during insulin secretion. The regulation of such changes may play an important role in controlling the rate of insulin secretion.