Table 1.

Relative specific activities of ¹³N-metabolites in rat brain after a 10 min-intracarotid artery infusion of [¹³N]ammonia

Metabolite	Controls (n = 4)	MSO-treated (n =4)	P
Glutamine (amide)	[100 ± 29]	8.0 ± 2.3	<0.03
Glutamine (amine)	1.2 ± 0.4	0.6 ± 0.2	NS
Glutamate	0.26 ± 0.07	1.4 ± 0.2	<0.03
Aspartate	0.56 ± 0.14	1.4 ± 0.6	NS

Tracer quantities of [¹³N]ammonia were administered to immobilized rats for 10 min by continuous infusion via a carotid artery. At the end of the infusion, brains were rapidly frozen, deproteinized and analyzed for ¹³N-labeled metabolites. Endogenous ammonia levels in the brains of control and MSO-treated rats were 0.181 ± 0.14 (n = 12) and 0.818 ± 0.098 (n – 12) μM, respectively. The specific activities of cerebral GDH in the control and MSO-treated rats were 196 ± 6 and 185 ± 4 μmol/h/g wet weight, respectively; the specific activities of cerebral glutamine synthetase in control and MSO-treated rats were 54.2 ± 2.5 and 7.5 ± 2.6 μmol/h/g wet weight, respectively (n = 12–24). Modified from Cooper et al. (1979). The data reported in this table and tables 2 and 3 are the mean ± SEM.