Previous studies have demonstrated that magnetic resonance imaging may be a method of choice to visualize transplanted pancreatic islets. However, contrast agents may interfere with microcirculation and affect graft function.To evaluate the effects manganese-containing contrast media on regional blood flow and glucose tolerance.Anesthetized rats were injected intravenously with MnCl2 (10 µM/kg body weight) or Mn-DPDP (Teslascan™; 5 µM/kg body weight). Blood flow measurements were made with a microsphere technique 10 min later. In separate animals vascular arteriolar reactivity in isolated, perfused islets was examined. Furthermore, an intraperitoneal glucose tolerance test was performed in separate rats.Glucose tolerance was unaffected by both agents. No changes in regional blood flow were seen after administration of Mn-DPDP, except for an increase in arterial liver blood flow. MnCl2 increased all blood flow values except that of the kidney. MnCl2, but not Mn-DPDP, caused a vasoconstriction in isolated rat islet arterioles but only at very high doses.Mn-DPDP administration does not affect glucose tolerance or regional blood flow, besides an increase in arterial hepatic blood flow, and may therefore be suitable for visualization of islets.
