ABSORPTION AND EXCRETION OF THIAMINE PROPYL DISULFIDE-S35. II. ABSORPTION AND EXCRETION OF THIAMINE PROPYL DISULFIDE-S35 (INNER).

Abstract

After injecting the labeled thiamine propyl disulfide, TPD-S35(outer), in the ligated intestines of dogs and rats, the total and free thiamine was measured. The amount of S35 was estimated in the contents of the ligated intestinal canal, the ligated portion of the intestine and the blood of mesenteric vein from the ligated portion. The results show that TPD moves rapidly into the tissues, where it is then reduced to thiamine, separating the propylmercapto radical.Matsubara (3) submitted a hypothesis concerning the absorption of TPD that the compound might be mainly reduced to thiamine in the intestinal canal, but some of it may pass through the intestinal canal in the form of TPD. A part of the reduced TPD might be resynthetheized to TPD, and the S-alkylmercaptocysteine, produced by reduction of TPD, may aid the absorption of thiamine in the intestinal canal.The results of our experiments revealed that a majority of the TPD administered entered the intestinal walls without being reduced, although some part of it may be reduced in the intestinal canal. The propylmercapto radical of TPD was separated shortly after its invasion into the intestinal canal. The S35 of the propylmercapto radical separated from TPD was excreted rapidly after absorption. 80 to 90 per cent of the S35 was excreted in urine and feces during a 41-hour period following oral administration of TPD-S35 (outer). However, 50 to 80 per cent was excreted in the urine and feces within 48 hours after intramuscular injection. In the contents of the small intestine, only 0.5-0.8 per cent of the administered radioactivity was found. The radioactive S35 found in the viscera following intramuscular injection were 1.5-4.5 per cent. Consequently, higher counts of S35 were found in the urine and feces after oral administration than after intramuscular injection.Marked discrepancies were noted when the results obtained after intravenous and oral administrations were compared. The findings suggest that TPD passes through the tissues in various ways according to the mode of administration. A part of the propylmercapto radical is separated when TPD was absorbed from the intestine and excreted through the lymphatic system.