Ar. Laptook et al., THE EFFECTS OF SYSTEMIC GLUCOSE-CONCENTRATION ON BRAIN METABOLISM FOLLOWING REPEATED BRAIN ISCHEMIA, Brain research, 638(1-2), 1994, pp. 78-84
Since systemic glucose concentration is an important determinant of is
chemic brain metabolism in neonates, we sought to determine if the sys
temic glucose concentration influences brain metabolic alterations fol
lowing repeated partial ischemia. A group of hyperglycemic piglets (n
= 12) were compared to a group of modestly hypoglycemic piglets (n = 1
2) using in vivo H-2 and P-31 magnetic resonance spectroscopy to simul
taneously measure cerebral blood flow and phosphorylated metabolites b
efore, during and 30 min after two 10-min episodes of ischemia (i.e. R
ecovery 1 and 2). For both groups, P-ATP levels at Recovery 1 and 2 we
re lower than Control (91 +/- 11 and 83 +/- 15% of Control, respective
ly for both groups combined, P = 0.002 vs Control). Inorganic phosphor
us was elevated in hyperglycemic piglets at Recovery 1 and 2 (117 +/-
15 and 118 +/- 10% of Control). In contrast, in modestly hypoglycemic
piglets inorganic phosphorus progressively rose from Recovery 1 (131 /- 24% of Control) to Recovery 2 (149 +/- 137% of Control), and differ
ed from the hyperglycemic group (P = 0.02). These changes did not corr
elate with post-ischemic cerebral blood flow, cerebral O-2 delivery or
cerebral glucose delivery. In both groups phosphocreatine and intrace
llular pH returned to Control values during Recovery 1 and 2. The prog
ressive increase in inorganic phosphorus post-ischemia in hypoglycemic
piglets suggests that modest hypoglycemia during and following repeat
ed partial ischemia adversely affects immediate brain metabolic recove
ry.