Mitochondrial function assessed by in vivo decarboxylation of α-ketoisocaproate is normal in patients with primary biliary cirrhosis

Abstract

Antimitochondrial antibodies (AMA) are a hallmark of primary biliary cirrhosis (PBC). Since these antibodies can inhibit mitochondrial enzymes in vitro, mitochondrial function was assessed in vivo in patients with PBC by following the decarboxylation of ketoisocaproic acid (KICA). After the administration of labelled KICA the exhalation of labelled CO 2 reflects mitochondrial function as previously shown in experimental animals and patients with alcoholic liver disease. In ten patients with PBC, five of whom had cirrhosis, the peak exhalation of CO 2 and the fraction of the administered dose appearing in breath were identical to healthy controls and patients with chronic viral or autoimmune hepatitis, but significantly higher than in a group of patients with alcoholic liver disease. It is concluded that, although some types of AMA inhibit the metabolism of branched chain oxoacids in vitro, mitochondrial function assessed by the decarboxylation of KICA in vivo is normal even in the cirrhotic stage of PBC.