Effects of guanidine derivatives on mitochondrial function: I. Phenethylbiguanide inhibition of respiration in mitochondria from guinea pig and rat tissues

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Abstract

Derivatives of guanidine, such as phenethylbiguanide, are potent inhibitors of mitochondrial respiration in vitro, but the relevance of this inhibition to their in vivo blood sugar-lowering action is not clear. We have studied the metabolism of pyruvate and long chain fatty acids by mitochondria from several tissues of guinea pigs and rats and observed the effects of phenethylbiguanide on these processes. The rate of pyruvate decarboxylation and of β-oxidation of long chain fatty acyl-CoA derivatives by guinea pig heart mitochondria in vitro has been found to exceed the flux of substrate through the citric acid cycle, both in the presence and absence of phosphate acceptor.

Authors

Frank Davidoff