PT  - JOURNAL ARTICLE
AU  - ACARA, MARGARET
AU  - RENNICK, BARBARA
TI  - RENAL TUBULAR TRANSPORT OF CHOLINE: MODIFICATIONS CAUSED BY INTRARENAL METABOLISM
DP  - 1972 Jul 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 1--13
VI  - 182
IP  - 1
4099  - http://jpet.aspetjournals.org/content/182/1/1.short
4100  - http://jpet.aspetjournals.org/content/182/1/1.full
SO  - J Pharmacol Exp Ther1972 Jul 01; 182
AB  - Renal tubular excretion of choline by the organic cation transport pathway was demonstrated in vivo in the chicken using the Sperber technique and in the dog by renal artery infusion and measurement of the extraction into urine. In the chicken, choline transport was apparent only at infusion rates above 0.5 x 10-6 mol/kg/min. At infusion rates lower than this there was intrarenal metabolism of choline to betaine. Betaine was not actively transported in the chicken or the dog. In the chicken, a transport maximum for choline was attained when 2 x 10-6 mol/kg/min were reaching the infused kidney and the transport maximum was 1 x 10-6 mol/kg/min. The urine from the infused kidney contained choline and three renal metabolites of choline which were separated by electrophoresis and chromatography. Betaine and acetyLcholine have been identified and a large metabolic fraction remains unidentified. Ultrafiltration and ultracentrifugation studies revealed that neither choline nor betaine were bound to plasma proteins. © 1972, by The Williams & Wilkins Company