Effects of the biguanide metformin on splanchnic blood flow in rats: preferential and dose-dependent increase in islet blood flow

Abstract

The aim of the present study was to evaluate if metformin, a biguanide used in the treatment of noninsulin-dependent diabetes, induced any changes in splanchnic circulation. For this purpose, anesthetized rats were injected intraperitoneally with saline alone (1 ml/kg BW) or metformin (15 or 30 mg/kg BW) 30 min before blood flow measurements. No effects on blood glucose or serum insulin concentrations could be discerned after administration of metformin. Both duodenal, whole pancreatic and islet blood flow were approximately doubled by the lowest dose (15 mg/kg BW) metformin. However, the higher dose (30 mg/kg BW) did not affect duodenal or pancreatic blood flow, whereas islet blood flow was markedly increased also in this group of animals. It is concluded that the blood flow to the pancreatic islets can be specifically enhanced by metformin. To what extent this contributes to the antihyperglycemic action of the drug is presently unknown.