Plasma transport and tissue distribution of [14C] beta-carotene and [3H]retinol administered orally to pigs.
The absorption, plasma transport, and tissue distribution of beta-carotene and vitamin A were studied in pigs after the oral administration of radiolabeled beta-carotene and retinol. Plasma radioactivity as well as retinol and beta-carotene were measured over a 24-h period, after which the pigs were killed. Plasma radioactivity increased within 4 h and 5 h for beta-carotene and retinol, respectively. The administration of radiolabeled retinol resulted in highest levels in the liver (83016 +/- 17614 dpm/g of tissue), followed by the kidney (5598 +/- 1309 dpm/g), the duodenum (2783 +/- 300 dpm/g), the colon (835 +/- 117 dpm/g), and the lung (756 +/- 68 dpm/g). Twenty-four hours after beta-carotene administration, tissue radioactivity distribution showed highest accumulation in the lung (22772 +/- 11997 dpm/g) and the liver (2328 +/- 694 dpm/g). The identification of the radioactive component 14C in the lung and colon indicated that the radioactivity was associated with beta-carotene only. This indicates that pigs may absorb intact beta-carotene. In other tissues such as liver, kidney, and intestine, only retinol-associated radioactivity was found after saponification of retinyl esters. The physiological importance of the unique accumulation of beta-carotene in lung tissue remains speculative.
Schweigert
F J
FJ
Department of Physiology, Physiological Chemistry, and Nutritional Physiology, Veterinary Faculty, Ludwig-Maximilians, University München, Germany.
Rosival
I
I
Rambeck
W A
WA
Gropp
J
J
D000284:Administration, Oral; D000818:Animals; D001692:Biological Transport / Q000502:physiology; D002250:Carbon Radioisotopes; D002338:Carotenoids / Q000032:analysis / Q000097:blood / Q000493:pharmacokinetics*; D003106:Colon / Q000737:chemistry / Q000378:metabolism; D004386:Duodenum / Q000737:chemistry / Q000378:metabolism; D005260:Female; D007668:Kidney / Q000737:chemistry / Q000378:metabolism; D008168:Lung / Q000737:chemistry / Q000378:metabolism; D013552:Swine / Q000378:metabolism*; D013997:Time Factors; D014018:Tissue Distribution; D014316:Tritium; D014801:Vitamin A / Q000032:analysis / Q000097:blood / Q000493:pharmacokinetics*; D019207:beta Carotene
D002250:Carbon Radioisotopes; D019207:beta Carotene; D014316:Tritium; D014801:Vitamin A; D002338:Carotenoids