[Catabolism of carnitine: products of carnitine decarboxylase and carnitine dehydrogenase in vivo].

Abstract

1) Rats and mice were given large oral or subcutaneous doses of (-)-L-, (+)-D- and DL-carnitine (5 mg/g body weight). The carnitine metabolites, beta-methylcholine and acetonyltrimethylammonium, were isolated from the urine by special methods, and determined as their characteristic derivatives (2,4-dinitrophenylhydrazone and butyric ester) by thin-layer chromatography or photometry. 2) beta-Methylcholine, the product of carnitine decarboxylase, was not excreted, even when animals were heavily dosed with both carnitine isomers, with or without starvation. 3) After the administration of (+)-D- and DL-carnitine, both species excreted acetonyltrimethylammonium, which is already known as the spontaneous decarboxylation product of dehydrocarnitine (product of carnitine dehydrogenase) in bacteria. Injection of 0.71 mmol (+)-D-carnitine resulted in the excretion of 5.0 mumol (average) acetonyltrimethylammonium per mouse during the 48 h post injection. Under the same conditions, rats produced up to 40 mumol acetonyltrimethylammonium. The ratio of excreted acetonyltrimethylammonium to injected (+)-D-carnitine depended on the method of administration and the dose. 4) Production of the pharmacologically active (+)-acetyl-L-beta-methylcholine is not to be expected, following high exogenous doses of (-)-L-carnitine or (-)-acetyl-L-carnitine. The chief metabolites are trimethylamine, trimethylamine oxide and gamma-butyrobetaine (this journal 361, 1059), and both the (-)-L-carnitine pool and exogenous (-)-L-carnitine are dehydrogenated or decarboxylated only to a very small extent, if at all. When DL-carnitine is used therapeutically, the formation of acetonyltrimethylammonium must be taken into account.

• Authors: H Seim, H Löster, E Strack
• Journal: Hoppe-Seyler's Zeitschrift fur physiologische Chemie (Hoppe Seylers Z Physiol Chem) Vol. 361 Issue 9 Pg. 1427-35 (Sep 1980) ISSN: 0018-4888 [Print] Germany
• Vernacular Title: Kataboler carnitinstoffwechsel: reaktionsprodukte der carnitin-decarboxylase und der carnitin-dehydrogenase in vivo.
• PMID: 7002759 (Publication Type: English Abstract, Journal Article)

Chemical References

• Quaternary Ammonium Compounds
• methylcholine
• Alcohol Oxidoreductases
• carnitine dehydrogenase
• Carboxy-Lyases
• carnitine decarboxylase
• acetonyltrimethylammonium
• Choline
• Carnitine

Topics

• Administration, Oral
• Alcohol Oxidoreductases (metabolism)
• Animals
• Carboxy-Lyases (metabolism)
• Carnitine (administration & dosage, metabolism)
• Choline (analogs & derivatives, urine)
• Chromatography, Thin Layer
• Female
• Mice
• Quaternary Ammonium Compounds (urine)
• Rats
• Stereoisomerism