Surplus acylcarnitines in the plasma of starved rats derive from the liver.

Sandor, A [Sándor, Attila (Biokémia), szerző] Biokémiai és Orvosi Kémiai Intézet (PTE / ÁOK); Cseko, J; Kispal, G [Kispál, Gyula (Biokémia), szerző] Biokémiai és Orvosi Kémiai Intézet (PTE / ÁOK); Alkonyi, I [Alkonyi, István (Biokémia), szerző] Biokémiai és Orvosi Kémiai Intézet (PTE / ÁOK)

Angol nyelvű Tudományos Szakcikk (Folyóiratcikk)
Megjelent: JOURNAL OF BIOLOGICAL CHEMISTRY 0021-9258 1083-351X 265 (36) pp. 22313-22316 1990
      The method used here to assess the contribution of liver to plasma acylcarnitine is based on the idea that in rat, shortly after administration of [3H]butyrobetaine the [3H]carnitine appearing in the plasma derives from the liver and so does the acyl moiety of [acyl-3H] carnitine. In the perchloric acid extracts of plasma and liver, the ester fraction of total carnitine was determined by enzymatic analysis and that of [3H]carnitines was determined by high performance liquid chromatography. The ester fraction of total carnitine in the plasma of fed rats was 32.6% while that of [3H]carnitines was 67.9%, 1 h following injection of [3H]butyrobetaine. For 48 h starved rats the equivalent values were 54.2 and 84.0%, respectively. 24 h after the administration of [3H]butyrobetaine, the ester content became the same in the total and [3H]carnitines. That the newly synthesized carnitine was more acylated (67.9 versus 32.6%, fed) indicates that liver exports acyl groups with carnitine as carrier. The observation that the ester fraction in the newly synthesized plasma carnitine increased with fasting (84.0 versus 67.9%) indicates that the surplus plasma acylcarnitine in fasting ketosis derives from the liver. Perfused livers, however, released carnitine with the same ester content (60-61%) whether they were from fed or fasted animals. Probably, the increased plasma [acylcarnitine] in fasting develops not by an increased ester output from the liver but by an altered handling in extrahepatic tissues.
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      2021-10-26 17:24