A continuous 48-hour glucose infusion in rats causes both an acute and a persistent redistribution of the blood flow within the pancreas.

Abstract

Male Sprague-Dawley rats were infused for 48 h at a rate of 1.8 ml/h with either a 30% solution of D-glucose or a 10% solution of D-mannitol. The blood perfusion of both the whole pancreas and the islets was measured with a microsphere technique either immediately after the infusion or 10 days later. Infusion of mannitol did not influence the serum glucose or the serum insulin concentration at any time point. Infusion of glucose, however, increased both the glucose and insulin concentrations during the infusion period, but 45 min after the infusion ended both the glucose and insulin concentrations had already returned toward the values found in the mannitol-infused rats. Intraperitoneal glucose tolerance tests were normal both immediately after the infusion and 8 days later. The glucose infusion caused a significant increase in whole pancreatic blood flow and islet blood flow when compared to mannitol-infused rats immediately after the infusion. The increase in blood perfusion of the islets was more marked than that to the whole pancreas since a larger fraction of the whole pancreatic blood flow was diverted through the islets. Ten days after the infusion there was still a marked increase in the fractional islet blood flow in the glucose-infused animals, whereas the absolute flow values for whole pancreatic or islet blood flow did not differ significantly between the groups. We conclude that continuous hyperglycemia for 48 h causes an acute increase in both whole pancreatic and islet blood flow, and that a redistribution of the blood flow within the gland is present 10 days after the infusion.