title: Net absorption of 3-methylindole and indole in cattle after oral administration of L-tryptophan.
abstract: The time course and quantity of 3-methylindole (3MI) and indole absorbed after oral administration of L-tryptophan (TRP) was determined in 2 steers. The relationship between the appearance of 3MI and indole in the rumen and blood plasma to absorption of 3MI and indole was also studied. Two Hereford X Angus steers with portal vein, mesenteric vein, and femoral (steer 1) or iliac (steer 2) artery catheters were used. Absorption rates from the portal drained viscera (net absorption) of 3MI and indole were determined by the product of portal and arterial concentration difference and blood flow. Blood flow was determined by primed continuous infusion of p-aminohippuric acid into a mesenteric vein. Three absorption measurements 30 minutes apart were taken at midpoint times of 0, 12, 24, 36, and 48 hours after oral administration of 0.4 g of TRP/kg of body weight. Steer 1 was dosed twice resulting in a total of 45 absorption measurements. Net absorption of 3MI and indole peaked at an average of 1.05 and 0.81 g/hr, respectively. By 48 hours, 29.2% and 15.3% of the TRP dose were accounted for by 3MI and indole absorption, respectively. Closed system in vitro incubations of TRP with ruminal fluid from the same 2 steers resulted in a TRP to 3MI conversion of 23.2% and a TRP to indole conversion of 10.7%. Net absorption of 3MI and indole closely followed and was correlated with concentration of 3MI and indole in ruminal fluid and blood plasma.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000042:Absorption; D000284:Administration, Oral; D000818:Animals; D002417:Cattle; D007211:Indoles / Q000032:analysis / Q000378:metabolism*; D008297:Male; D011016:Pneumonia, Atypical Interstitial, of Cattle / Q000378:metabolism*; D012417:Rumen / Q000032:analysis; D012862:Skatole / Q000032:analysis / Q000378:metabolism*; D013997:Time Factors; D014364:Tryptophan / Q000008:administration & dosage / Q000378:metabolism*
chemical_list: D007211:Indoles; C030374:indole; D014364:Tryptophan; D012862:Skatole