1-Methyl-tetrahydro-beta-carboline-3-carboxylic
acid (
MTCA) may cause
eosinophilia-myalgia syndrome (EMS) associated with ingestion of
L-tryptophan. The distribution and excretion of
MTCA were studied in rats which had received perorally a single 1.6 mg/kg dose of
MTCA.
MTCA concentrations in blood, kidney, liver, brain, heart, spleen, lung and gastrocnemius muscle were measured by HPLC combined with fluorometric detection. The concentration of
MTCA in each organ reached a maximum at 1 h and then gradually declined. However, a significant level of
MTCA still remained at 5 h, when 52% of ingested
MTCA remained in the contents of the large intestine. Twenty-nine percent of the ingested
MTCA was excreted in urine over the course of 24 h. A higher dose (10 mg/kg) of
MTCA resulted in significant elevations in the concentrations and amounts of
MTCA in the various organs. In addition, chronic treatment with
a 10 mg/kg dose of
MTCA for 6 weeks further increased the concentrations and amounts of
MTCA in each organ. However, no histological changes were observed in any of the organs after chronic treatment. This is the first report which demonstrates accumulation of
MTCA in the blood and various organs, including muscle, of rats.