Nuclear magnetic resonance as a measure of cerebral metabolism: effects of hypertonic saline resuscitation.
Fears of central nervous system dysfunction from acute hypernatremia and hyperosmolarity with hypertonic saline resuscitation are often cited. We used high-energy phosphate nuclear magnetic resonance to investigate resuscitation effects on cerebral metabolism. Rats were instrumented for hemodynamic monitoring and fluid infusion and a phosphorus surface coil placed on their skulls. After shimming, baseline spectra were obtained. Animals were then bled for one hour to a mean arterial pressure (MAP) of 45 mm Hg, followed by resuscitation for one hour to a MAP of 75 mm Hg with lactated Ringer's (LR, n = 17) or 7.5% hypertonic saline (HS, n = 25). Spectra were obtained again and analyzed for the ratio of high-energy phosphocreatine (PCr) to low-energy inorganic phosphate (Pi). Intracellular hydrogen ion concentration [H+] was calculated from the PCr/Pi shift. [table: see text]


CONCLUSIONS
(1) Hypertonic saline results in a decreased intracellular pH compared with LR without associated changes in high-energy phosphate metabolism. (2) Decreases in pH may be the result of cell dehydration rather than metabolic dysfunction.
Wisner
D H
DH
Department of Surgery, University of California, Davis, Medical Center, Sacramento 95817.
Battistella
F D
FD
Freshman
S P
SP
Weber
C J
CJ
Kauten
R J
RJ
D000818:Animals; D001921:Brain / Q000378:metabolism*; D004195:Disease Models, Animal; D006863:Hydrogen-Ion Concentration; D006955:Hypernatremia / Q000209:etiology / Q000378:metabolism*; D007552:Isotonic Solutions; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D009994:Osmolar Concentration; D051381:Rats; D011919:Rats, Inbred Strains; D000077325:Ringer's Lactate; D012462:Saline Solution, Hypertonic / Q000009:adverse effects*; D012771:Shock, Hemorrhagic / Q000628:therapy
D007552:Isotonic Solutions; D000077325:Ringer's Lactate; D012462:Saline Solution, Hypertonic