Table 1.

Summary of cerebral metabolite data and metabolic rates

Group	n	[Glutamate]	[Glutamine]	Glutamate enrichment	VTCA	VGln	CMRGlc(ox)¶	Vcycle‖
		(μmol/g)			(μmol/min/g)
(A) morphine sulfate	5	11.2  ±  1.0*	5.3  ±  0.7	0.50  ±  0.04†	1.01  ±  0.23‡	0.44  ±  0.07§	0.50  ±  0.12	0.40  ±  0.07
(B) α-chloralose	6	9.4  ±  1.7	5.7  ±  1.6	0.22  ±  0.02	0.53  ±  0.08‡	0.17  ±  0.05§	0.26  ±  0.04	0.13  ±  0.05
(C) sodium pentobarbital	6	8.1  ±  0.9*	6.0  ±  0.6	0.27  ±  0.02	0.16  ±  0.08‡	0.04  ±  0.02§	0.08  ±  0.04	0**

All values are expressed as the mean ± S.D.

^*Significantly different (Bonferroni t test, P < 0.005).

^†The fractional enrichment of glutamate in group A was ≈ twice that measured in the other groups as [1,6-¹³C]Glc rather than [1-¹³C]Glc was infused in these animals.

^‡Multiple-comparison Bonferroni t tests demonstrated significant differences (P < 0.001) among each of the groups for V_TCA.

^§Multiple-comparison Bonferroni t tests demonstrated significant differences (P < 0.001) among each of the groups for V_Gln.

^¶The rate of cerebral oxidative Glc consumption (CMR_Glc(ox)) was calculated from the measured V_TCA.

^‖The rate of neurotransmitter cycling (V_cycle) was determined from the measured rate of Gln synthesis (V_Gln).

^**V_cycle in group C was assumed to be zero as all electrical activity (determined from EEG recordings) had been eliminated.