Abstract
The plasma levels of four monocarboxylic short-chain fatty acids (SCFA) were determined gas-chromatographically in 10 normal subjects, 27 nontreated diabetics and 15 nontreated hyperthyroidism according to a modification of the methods of Mahadevan et al. The concentrations of acetate and propionate were markedly increased in diabetics. In particular, there was a close correlation between the acetate concentrations and levels of fasting blood sugar. These phenomena are explained on the basis of impaired functions of acetyl-CoA carboxylase (EC 6. 4. 1. 2.) and acetyl-CoA synthetase (EC 6. 2. 1. 1.). It appears likely that such impairments cause under-utilization of active forms of these organic acids and eleveated plasma concentrations of the free acids. The concentrations of isobutyrate and isovalerate were not significantly different among the various experimental groups.
Since the origins and physiological significance of these SCFA have not yet been thoroughly elucidated, they require further study in relation to branched-chain amino acids, pyruvate, citrate, lactate and medium-chain fatty acids.
