Ontogeny of L-Glutamic Acid Decarboxylase and γ-Aminobutyric Acid Concentration in Human Kidney

Abstract

Pediat. Res. 9: 484-487 (1975) Extract particular importance in man, who extracts glutamine from the Mature human renal cortex contains y-aminobutyric acid (GABA) at concentrations on the order of 0.2 p n o l / g wet wt and about half of that concentration in fetal kidney.a -A m i n o b u t y r i c acid h u m a n kidney g l u t a m i c acid decarboxylase pyridoxal p h o s p h a tThe pyridoxal-5'-phosphate (PLP)-dependent enzyme, Lglutamic acid decarboxylase (GAD), catalyzes the conversion of L-glutamate to GABA. The PLP-saturated GAD activity in post-term ( 1 day-9 years) renal cortex homogenate is 0.94 A 0.38 p n o l CO, formed/g wet wt/hr (Table 1). The corresponding GAD activity in fetal renal cortex, in the midtrimester and early third trimester, is 0.28 0.19 p n o l CO, formed/g wet wt/hr (P < 0.01 vs. post-term activity). GAD activity increases during gestation to reach levels at birth equivalent to mature kidney. When corrections are made for the difference in tissue water between fetal and mature kidney, they do not ablate the post-term increase in GAD activity.Renal GAD was undersaturated with P L P in 12 of 21 specimens examined; 8 of these specimens were of fetal origin (Table 1 and Fig. 2). Undersaturation was revealed when addition of P L P (0.24 m M ) to the homogenate stimulated activity by 2 5 3 0 0 % in the 12 specimens. GAD activity in rat kidney binds P L P avidly and is always saturated with P L P under the normal laboratory conditions of vitamin B, nutrition. Undersaturation of renal GAD in man may imply inadequate endogenous availability of vitamin B, coenzyme.The GABA pathway in mammalian kidney has been implicated in the maintenance of normal acid-base balance. Renal G A D is increased in the postnatal subject relative to fetal GAD activity in support of this hypothesis. Undersaturation of fetal GAD with its PLP-coenzyme in two-thirds of the fetal specimens may have implications concerning intrauterine nutrition and renal development.

Autoradiographic distribution of radioactivity from 14C-GABA in the mouse

“…In addition, there is plenty of evidence that GABAergic neurons are present in the peripheral nervous system of the mammalian gastrointestinal tract (Tanaka, 1985;Tanaka and Taniyama, 1985;Taniyama et al 1983Taniyama et al , 1987 and urinary bladder (Kusunoki et al 1984;Shirakawa et al 1989). Furthermore, there is also evidence that certain nonneuronal tissues such as pancreas (Garry et al, 1987(Garry et al, , 1988Gilon et al, 1987;Gilon and Remacle, 1989), kidney (Lancaster et al, 1973(Lancaster et al, , 1975, lung (Erdö and Amenta, 1986), female reproductive organs (Del Rio and Caballero, 1980;Erdö et al, 1983a), male reproductive organs (Erdö et al, 1983b), and adrenal glands (Oomori et al, 1993) contain significant amounts of GABA. In these tissues and organs besides those of the central nervous system, GABA is considered a neurotransmitter or neuromodulator.…”