抄録
The mechanism of incorporation of ATP into fat and red cells of the rat was studied using [8-14C] ATP, [γ-32P] ATP, [8-14C] AMP, and [8-14C] adenosine. ATP was incorporated into these cells after dephosphorylation, but a very small portion of ATP added appeared to cross the cell membranes directly. After entry, dephosphorylated nucleotide was re-utilized for synthesis of ATP.
Furthermore, the in vivo absorption mechanism and distribution of intraduodenally administered ATP and AMP were studied using [8-14C] ATP, [γ-32P] ATP, and [8-14C] AMP. Large amounts of ATP and AMP were dephosphorylated, absorbed into the plasma and incorporated into various tissues, but a very small amount of ATP appeared to cross the intestinal mucous membrane directly. The distribution of radioactive metabolites of ATP in plasma and tissues differed from that of AMP. A considerable amount of ATP was detected in almost all tissues upon administration of ATP, whereas no ATP was detected upon administration of AMP, except in the kidney and liver. The results of analysis of radioactive metabolites of these two nucleotides in portal plasma showed that 40% of total radioactivity in the plasma was accounted for by AMP with intraduodenal administration of ATP, while intraduodenally administered AMP was degraded very rapidly to uric acid and allantoin, and 9% of total radioactivity was accounted for by AMP.
