AJP - Cell Physiology, Vol 257, Issue 6 C1055-C1061, Copyright © 1989 by American Physiological Society
An in vivo examination of rat brain during sepsis with 31P-NMR spectroscopy
R. S. Hotchkiss, R. C. Long, J. R. Hall, G. T. Shires 3rd, R. G. Brouillard, W. J. Millikan and D. P. Jones
Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri 63110.
Neurological symptoms including lethargy, obtundation, and confusion are
early and common findings in patients with sepsis. The etiology of the
mental status changes that occur during severe infection is not known. We
investigated the effects of sepsis on the levels of high-energy phosphates
to determine whether decreased energy metabolism was a factor in the
depressed neurological state. The time course of changes in brain pH and
brain high-energy phosphate metabolites during an Escherichia coli infusion
was determined from sequential phosphorus-31 nuclear magnetic resonance
(31P-NMR) spectra of ketamine-xylazine-anesthetized rats. A second group of
rats received 0.9% saline infusion and served as a control group. Despite
severe obtundation and near loss of righting reflex, the rats in the septic
group had no significant differences in the brain pH, the ratio of
phosphocreatine (PCr) to beta-adenosine 5'-triphosphate (beta-ATP), or in
the ratio of PCr to Pi. The only significant decrease in brain high-energy
phosphates or pH occurred terminally in the septic rat group and
corresponded with a rapidly falling arterial blood pressure. We conclude
that the severe neurological depression that is characteristic of sepsis is
not due to decreased levels of brain high-energy phosphates or brain
acidosis.
