Donald Polin

In vivo Absorption of Amprolium and Its Competition with Thiamine

Summary Ligated intestinal sections of the digestive tract in chicks were injected in vivo with 8 mg of the coccidiostat, amprolium. Only the duodenum absorbed significant amounts of the drug (91%) in a 1-hour absorption period. A dose-absorption curve for the duodenum revealed a linear response to about 12 mg and a plateau portion associated with fluid accumulation in loops when higher doses of the drug were introduced. Thiamine introduced simultaneously with .315 mg of amprolium (an antimetabolite of thiamine) decreased amprolium absorption significantly when thiamine/amprolium ratios exceeded 4, and amprolium in excess over thiamine decreased thiamine absorption at molar ratios exceeding 7.5.

Studies on thiamine absorption.

Summary Thiamine absorption from intestinal tract of chicks was studied using ligated loops or analyzing tract contents for C14 and thiamine in chicks fed thiamine-2-C14. In one hour about 84% of a 250 μg dose of thiamine was absorbed from chick duodenal loops, but only barely detectable amounts of 7 to 15% from ceca and upper and middle sections of remaining small intestine. No absorption occurred at this dose from crop or lower small intestine. A thiamine dose-absorption curve for duodenum was linear up to doses of 10 mg. Proportionately less thiamine was absorbed from middle small intestine as doses increased in ligated loops from 6.25 to 100 μg; yet in duodenum almost 90% of the 100 μg dose was absorbed. Chicks fed 5.8 or 10.6 ppm thiamine in stock rations had a similar profile in intestinal tract concentrations with lowest value in middle ⅓ of small intestine. Chicks fed 127 ppm thiamine had progressively increasing thiamine concentrations in sections of small intestine distal to duodenum. The data indicate that thiamine is absorbed primarily in the upper small intestine and when fed at very high levels to chicks is secreted by intestinal mucosa of middle and lower sections of small intestine.

Formation of Porphyrin from Delta-Aminolevulenic Acid by Uterine and Liver Tissue from Laying Hens.

Summary 1. Uterine tissue, from white or brown egg-laying hens, forms twice as much porphyrin, in vitro, from delta-aminolevu-lenic acid as liver tissue. Supernatant preparations of uterine tissue form predominately uroporphyrin, small amounts of protoporphyrin, and trace amounts of coproporphyrin from delta-aminolevulenic acid. These compounds were tentatively identified by their behavior in the fractionation procedure used and by their absorption curves. 2. Oopor-phyrin and coproporphyrin were extracted from the glandular tissue of the uterus of laying hens.

Porphyrin Formation by Tissues from Laying Hens Fed Nicarbazin.

Summary Feeding nicarbazin to laying hens resulted in less protoporphyrin on their egg shells. The decrease varied in proportion to dietary intake and a linear response was obtained between dietary levels of 0.002–0.010% nicarbazin. Tissue homogenates of follicular membranes, magnum. isthmus, uterus, and small intestines from laying hens catalysed the formation of porphyrins from ALA. Homogenates of isthmus and uterus were more potent than those of other tissues examined. Tissues from medicated hens formed as much porphyrin from ALA as those from nonmedicated hens. Erythrocyte-porphyrin formation induced by repeated bleeding was not inhibited in medicated hens which were laying eggs with shells containing 75% less porphyrin than controls. These data suggest that decreased deposition of shell protoporphyrin caused by feeding nicarbazin does not result from inhibition of porphyrin synthesis.

Amprolium 10. Influence of Egg Yolk Thiamine Concentration on Chick Embryo Mortality

Summary Free thiamine concentrations in yolk decreased from 3 to .4 ppm when adult White Leghorn females were fed .2% amprolium. The lowest free vitamin concentration in yolk was reached by day 11 on medication, but maximum effect on the hatch did not occur until the 3rd week on medicated diets. On withdrawal of medication, free thiamine in yolk returned to original concentration in 6 days while normal hatches were obtained in 3 days. Minimum free thiamine in yolk for optimum hatch was found to be about .63 ppm.

Antagonistic Effect of Thiocarbanilide on 4,4′-Dinitrocarbanilide, A Component of Nicarbazin

Summary 1) Thiocarbanilide, in a 1 to 1 ratio or less, effectively inhibited the anticoccidial activity of nicarbazin when given parenterally as well as orally. 2) Thiocarbanilide also antagonized the effect of nicarbazin on the depigmentation of egg shell color. 3) In both instances, the antagonistic effect of thiocarbanilide was correlated with decreased plasma concentrations of dinitrocarbanilide. 4) It is suggested that thiocarbanilide may interfere with the activity of nicarbazin through competition in absorption.