Ssf. Hsu et al., MODERATE HYPERGLYCEMIA AFFECTS ISCHEMIC BRAIN ATP LEVELS BUT NOT INTRACELLULAR PH, The American journal of physiology, 266(1), 1994, pp. 80000258-80000262
We used P-31 nuclear magnetic resonance (NMR) spectroscopy to study th
e effect of moderate hyperglycemia on brain ATP and intracellular pH i
n a model of severe incomplete forebrain ischemia. Plasma glucose in t
he hyperglycemic rats was 277 +/- 9 mg/100 ml compared with 115 +/- 10
mg/100 ml in the normoglycemic rats at the onset of ischemia. After 1
5 min of ischemia, brain ATP levels decreased to 31 +/- 8% in normogly
cemic rats vs. 63 +/- 11% in hyperglycemic rats (P < 0.05). Phosphocre
atine levels were 31 +/- 9 and 55 +/- 8% for normoglycemic and hypergl
ycemic rats, respectively. Intracellular pH decreased to the same leve
l (similar to 6.5) in both normoglycemic and hyperglycemic animals aft
er 15 min of ischemia. In summary, we found that moderate hyperglycemi
a during severe incomplete forebrain ischemia significantly increases
ischemic brain ATP levels but does not have a significant effect on in
tracellular pH. These results support the hypothesis that alterations
in brain ATP and adenosine concentrations may be important in the path
ogenesis of ischemic tissue injury under moderate hyperglycemic condit
ions, whereas alterations in tissue pH may be less important.