The regulation of one-carbon oxidation in the rat by nitrous oxide and methionine

• Published in: Archives of biochemistry and biophysics Vol. 219; no. 2; pp. 316 - 326
• Main Authors: Eells, J.T., Black, K.A., Makar, A.B., Tedford, C.E., Tephly, T.R.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.12.1982
• Subjects: Animals; Carbon Radioisotopes; Folic Acid - metabolism; Formates - metabolism; Kinetics; Liver - metabolism; Male; Methionine - pharmacology; Nitrous Oxide - pharmacology; Oxidation-Reduction; Rats; Rats, Inbred Strains
• ISSN: 0003-9861; 1096-0384
• DOI: 10.1016/0003-9861(82)90162-X

Formate is oxidized to CO 2 in the rat by folate-dependent reactions. Nitrous oxide treatment inhibited hepatic methionine synthetase activity, reduced hepatic S-adenosyl- l-methionine (Ado-Met) and tetrahydrofolate (H 4 folate) concentrations and decreased the rate of formate oxidation in the rat. The administration of methionine to nitrous oxide-treated rats increased hepatic Ado-Met concentrations and restored hepatic H 4folate levels and formate oxidation to control values but did not reverse the inhibition of methionine synthetase. Positive correlations were observed between hepatic Ado-Met levels and H 4folate concentrations and between hepatic H 4folate concentrations and formate oxidation. These results suggest that alterations in hepatic H 4folate concentrations may profoundly influence the oxidation of one-carbon compounds. They confirm the importance of the methionine synthetase reaction as a major source of regeneration of H 4folate. These findings also indicate that methionine acts at a site other than the methionine synthetase reaction to restore hepatic H 4folate concentrations and formate oxidation to control values in nitrous oxide-treated rats.