Henk M. De Feyter1, Kevin L. Behar2, Robin A. de Graaf, Douglas L. Rothman,3
1Diagnostic Radiology, Yale University, New Haven, CT, United States; 2Department of Psychiatry, Yale University; 3Department of Biomedical Engineering, Yale University
Increased blood-to-brain transport of monocarboxylic acids (MCA's) by monocarboxylate transporter 1 (MCT1), has been suggested as an adaptation contributing to hypoglycemia unawareness. Lactate is the MCA with the highest concentration present during hypoglycemia. We investigated the role of blood lactate as alternative fuel during hypoglycemia by studying brain lactate transport and metabolism in healthy rats during hyperinsulinemic euglycemia and acute hypoglycemia using in vivo 1H-[13C] magnetic resonance spectroscopy (MRS) combined with [3-13C]-lactate infusion. The in vivo MRS data presented indicate actively regulated lactate transport over the blood-brain barrier responsive to plasma glucose levels.