Preferential Utilization of Lactate in Neonatal Dog Brain: In vivo and in vitro Proton NMR Study

Abstract

In vivo proton nuclear magnetic resonance spectroscopy was utilized to determine whether lactate is preferentially utilized as metabolic fuel by the neonatal dog brain. The data showed that during lactate influx, metabolism of lactate could account for most of the fuel needed for oxidative metabolism. The in vivo nuclear magnetic resonance measurements were corroborated by conventional arteriovenous determinations which showed steep decline of arteriovenous difference of glucose and shaφ increase in arteriovenous difference of lactate during lactate infusion.

Nonlinear Kinetics of Lactate Uptake across Blood-Brain Barrier

“…It has been suggested [5] that the rate of change of tissue metabolite amount depends on the passage between blood and tissue a bothway process, and the rate of tissue oxi dation of the metabolite. It is advisable therefore that the authors [ 1 ] use a different model to achieve a better fit to their data in accordance with the foregoing recommenda tions.…”

“…Howard S Mehler PhD JD & Associates Incorporated, Los Angeles, Calif., USA The paper by Young et al [1] contains material inaccuracies in the quantitative in terpretation of data which we believe should be brought to the attention of the scientific community. The authors explicitly state on page 47:…”

“…An additional patent defect in the model promulgated by the authors [ 1 ] is the failure of their differential equation to account for all of the metabolic forces determining the rate of change of brain lactate concentration (dCbr/dt). For example, their model fails to distinguish between lactate efflux from brain and the oxidation of lactate within the tissue.…”

Hyperglycemia and the Rate of Lactic Acid Accumulation during Cerebral Ischemia in Developing Animals: In vivo Proton MRS Study

“…The animals were anesthetized with halothane (induction, 3.5%; maintenance, 1%) while undergoing tracheot omy and placement of a femoral arterial catheter as described in previous work [19,20]. Following inser tion of the catheter, halothane was discontinued, and the animals were mechanically ventilated to provide normoxia and normocarbia (table 1).…”

“…How ever, these studies necessitated the decapita tion and rapid freezing of the heads of multi ple groups of animals at different time points. The rate of lactic acid production during cere bral ischemia may be more accurately deter mined with in vivo proton magnetic reso nance spectroscopy (MRS) because of its abil ity to make sequential measurements in the same animal [13,19,20].…”