The effect of enteral carnitine administration in humans.
We previously determined that the L-carnitine uptake by human duodenal tissue occurs by both active (KT 558 mumol/L) and passive mechanisms. The effects of enteral carnitine was studied in humans. A hamburger meal (345 mumol total carnitine) induced peak jejunal fluid free (unesterified) and short-chain acylcarnitine concentrations (SCAC) of 209 and 130 mumol/L, respectively. Plasma carnitine concentrations and the percent renal reabsorption remained unchanged. By contrast, a pharmacologic dose of free carnitine (25,298 mumol) raised peak intraluminal free and SCAC to 20,660 and 4204 mumol/L. Plasma total carnitine concentrations doubled to 93 mumol/L, and the percent renal reabsorption of free and SCAC declined to 76% and 52%, respectively. In triple-lumen perfusions, 200 mumol carnitine/L was absorbed at 484 nmol.min-1.30 cm-1 jejunum, a rate sufficient for prandial but not pharmacologic assimilation. Our findings indicate that absorption of physiologic and pharmacologic amounts of carnitine occurs predominantly by active transport and passive diffusion, respectively.
Li
B
B
Department of Pediatrics, Ohio State University, Columbus.
Lloyd
M L
ML
Gudjonsson
H
H
Shug
A L
AL
Olsen
W A
WA
D000042:Absorption; D000293:Adolescent; D000328:Adult; D002331:Carnitine / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D005502:Food; D006801:Humans; D007408:Intestinal Absorption; D007583:Jejunum / Q000378:metabolism; D007668:Kidney / Q000378:metabolism; D008297:Male
D002331:Carnitine