Intranephron Distribution of Glycine-Amidinotransferase Activity in Rats
作者:
Michio Takeda,
Hikaru Koide,
Kyu Yong Jung,
Hitoshi Endou,
期刊:
Kidney and Blood Pressure Research
(Karger Available online 1992)
卷期:
Volume 15,
issue 3-4
页码: 113-118
ISSN:1420-4096
年代: 1992
DOI:10.1159/000173449
出版商: S. Karger AG
关键词: Guanidinoacetic acid;Glycine-amidinotransferase;Microdissected nephron segment
数据来源: Karger
摘要:
Guanidinoacetic acid (GAA), a precursor of creatine, is an essential substrate for muscle energy metabolism, and synthesized by glycine-amidinotransferase (transamidinase) mainly in the kidney. Since the intranephron distribution of transamidinase activity has never been quantified yet, the purpose of this study is to provide evidence about the localization of transamidinase activity using microdissected individual nephron segments. Synthesized GAA was separated by HPLC and detected fluorometrically after reacting with 9,10-phenanthrenequinone. Results obtained were as follows. (1) Transamidinase activity was distributed only in the first (S1) and the second (S2) portion of the proximal tubule Si being significantly higher than S2. (2) In S2, arginine and glycine were better substrates for GAA synthesis than canavanine and glycine. These results clearly indicate that GAA is synthesized in definite portions of the proximal tubule, and would be transported to the liver for further creatine production.
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