5006 C. F. BAXTER AND E. ROBERTS 
of lysine have been shown to increase in muscle of potassium-deficient rats!®. The 
most remarkable change produced by aminooxyacetic acid was the spectacular 
increase in GABA concentration of brain (Figs. 33-34) at a time when no significant 
changes occurred in the level of any of the other amino acids which were detected by 
our chromatographic procedure. The highest levels of GABA in brain were observed 
at about 3 h after injection. This time differs from that reported by others: ?° who 
found that a maximal elevation of GABA was not attained until 6h after the in- 
jection of aminooxyacetic acid. 
The assay of brains from rats treated with aminooxyacetic acid showed that the 
inhibition of GABA-T and the elevation of levels of GABA correlated well in time 
for the first 7 h after intraperitoneal injection (Table III). During this time period 
os Macs | 
ee 
. o 
he = ae 
a ~~ 
7 Z # 
31 32 
2 7 
- sat 
al a 
ae , 
an tame etal re te | F 
Ws , 
Figs. 29-34. Effect of aminooxyacetic acid upon the concentration of amino acids in tissues of 
rat. Injected dose NH,OCH,—COOH-1/, HCl, (adjusted to pH 6): 100 mg/kg. Figs. 29-30: 
heart; the arrows point to lysine. Figs. 31-32, muscle. Figs. 33-34: brain cortex; the arrows 
point to GABA. All odd numbered chromatograms represent tissues from normal control animals; 
all even numbered chromatograms illustrate changes in the tissues of treated animals. 
References p. 508 
