Subcellular distribution of β-carotene, retinol, and α-tocopherol in porcine lymphocytes after a single injection of β-carotene

Abstract

The subcellular distribution of β-carotene, retinol, and α-tocopherol in lymphocytes was studied in pigs (50 to 55 kg) injected once with 0, 20, or 40 mg of β-carotene. Blood was sampled at 0, 24, 48, and 72 h postinjection. Plasma β-carotene in treated pigs peaked at 24 h and decreased rapidly thereafter. Beta-carotene was found in all subcellular fractions of lymphocytes. Concentrations in nuclei mirrored changes in plasma. However, β-carotene in mitochondria and cytosol peaked at 24 h, whereas that in microsomes peaked at 48 h. Concentrations in the latter three subcellular fractions remained high at 48 and 72 h even though plasma β-carotene had decreased to very low concentrations. Peak concentrations of β-carotene were highest in the nuclei, intermediate in the mitochondria and microsomes, and lowest in the cytosol. Treatment did not influence concentrations of retinol or α-tocopherol in the various subcellular fractions. These data provide more compelling evidence for the possible role of β-carotene in lymphocytes.