Table 2.

Metabolite Concentrations (mmol/kg wet eight) in Rat Cerebral Cortex During Ammonia-Induced and L-Methionine-S,R-Sulfoximine (MSO)-Induced Intoxication.

Metabolite	Control (NaAc-Infused)	NH4Ac-Infused	MSO-Treated + NaAc-Infused	MSO-Treated + NH4Ac-Infused
Ammonia (blood)	0.191 ± 0.063	0.710 ± 0.150 *	0.432 ± 0.089 *	1.02 ± 0.07 *
Ammonia	0.326 ± 0.063	0.985 ± 0.084	0.855 ± 0.031	2.48 ± 0.06
α-Ketoglutarate	0.096 ± 0.011	0.112 ± 0.011	0.157 ± 0.006 *	0.141 ± 0.018 *
L-Glutamate	12.9 ± 0.4	11.1 ± 0.3 *	10.1 ± 0.3 *	11.6 ± 0.4 *,†
L-Glutamine	8.04 ± 0.019	18.5 ± 0.8 *	3.79 ± 0.54 *	6.97 ± 1.00 *

Adult male Wistar rats were anesthetized and catheters were inserted into a tail artery and one tail vein. The rats were tracheotomized, curarized and passively ventilated with 30% O₂–70% N₂O. Blood temperature and acid-balance were maintained within normal limits. Animals that received MSO were injected with 150 mg/Kg (a dose designed to substantially inhibit glutamine synthetase by >90% but not to induce seizures) 2.0–2.5 h before infusions were begun. The rats were then infused intravenously with either 3 M sodium acetate (NaAc) or 3 M ammonium acetate (NH₄Ac) for 2 h at a rate of 6.2 μL/min, after which times the animals were euthanized by freezing the brains in situ with liquid N₂. The brains were removed, powdered under liquid N₂, weighed at −20 °C and extracted with 3 M perchloric acid. Metabolites in the neutralized perchlorate extract were analyzed as described in ref. [95]. n = 4 or 5 in each group. * p < 0.01 by Dunett’s test for multiple comparisons; ^† different from the value obtained with the MSO/NaAc-treated rats with p < 0.05 by the Student t test. Modified from ref. [102].