AbstractOxidative phosphorylation and respiratory enzyme concentrations of liver mitochondria and glucose tolerance were studied in 12 cirrhotic patients and CCl4-induced cirrhotic rats. The cirrhotic patients with normal or higher concentrations of cytochrome a(+a3) showed parabolic glucose tolerance test (GTT) patterns having return of blood glucose level somewhat toward normal within two hours and tolerated major operations well, while three patients with cytochrome a(+a3) concentrations less than 60 per cent of normal (0.81±0.02 (mean±SEM) × 10-10moles/mg protein) could not tolerate even minor operations. In CCl4-induced cirrhotic rats, cytochrome a(+a3) concentrations varied from 1.5 to 3.0 × 10-10moles/mg protein as compared with 1.8±0.1 of controls. In mitochondria with normal or higher concentrations of cytochrome a(+a3), the oxidative and phosphorylative activities per unit of cytochrome a(+a3) were negatively correlated with cytochrome a(+a3) concentrations. These rats tolerated partial hepatectomy well. However, in cirrhotic rats with subnormal cytochrome a(+a3) concentrations there was a high mortality following hepatectomy. The former showed parabolic GTT patterns, while the latter showed non-parabolic GTT patterns.