Abstract
The conversion of thiamine and its lipophilic derivative BuTDS into cocarboxylase was investigated by rabbit erythrocytes in Tyrode's medium containing glucose. The concentration of cocarboxylase in erythrocytes increased gradually up to 2〜3 fold by the incubations with the vitamins. Under lower concentrations of the vitamins in the medium, the increased amount of cocarboxylase by the incubation with BuTDS was higher than with thiamine. The absence of glucose in the medium leads to the significant decrease of cocarboxylase formation. The conversion of thiamine into cocarboxylase in the erythrocytes suspension was inhibited markedly by the presence of pyrithiamine. The blood cocarboxylase levels were compared after intravenous injections of thiamine, BuTDS or cocarboxylase. It was observed that the cocarboxylase concentration increased by the administration of BuTDS was 3〜4 times higher than that of thiamine, and that the decrease rate of cocarboxylase in erythrocytes was much more slower than in plasma. It was recognized that cocarboxylase had little permeability to erthrocytes in both in vitro and in vivo.
