Proton magnetic resonance spectroscopic studies of agonal carbohydrate metabolism in rabbit brain

1H magnetic resonance spectroscopic measurements of cerebral lactate accumulation were used to estimate maximum agonal cerebral glycolytic rate (AGR) after cardiac arrest in 10 rabbits, six of which had received cortical electroshock. In the four control rabbits, mean AGR was 3.1 mumol glucose equivalents/g wet weight/min (standard error of the mean, 0.6), a figure in close agreement with earlier studies by workers using other techniques. AGR depended much more on carbohydrate availability as expressed by terminal blood glucose than on the shock-conditioned state of the glycolytic system reflected by individual rate constants of lactate accumulation. Regardless of shock history, AGR rose with blood glucose as though it were limited only by substrate availability. The unique capability of magnetic resonance spectroscopy to obtain chemically specific time course data noninvasively made these observations possible. The method has considerable potential for further analysis of normal and deranged cerebral metabolism.