Effects of Branched-Chain Amino Acids on Muscle Ammonia Metabolism in Patients With Cirrhosis and Healthy Subjects

The purpose of this study is to determine whether Branched chain Amino Acids enhances the uptake of ammonia in muscle tissue.

Branched-chain amino acids (BCAA; leucine, valine, isoleucine) are used to prevent hepatic encephalopathy in cirrhotic patients. The main effect of BCAAs is believed to take place in muscles where BCAAs provide carbon-skeletons for the TCA-cycle. This enhances the conversion of alfa-ketoglutarate to ammonia via glutamine. We intend to study the effect of oral administered BCAA on the metabolism of ammonia and amino acids across the leg-muscles by means of catheters inserted into the femoral artery (A) and vein (V). Muscle blood flow (F; L/min) will be determined by constant infusion of indocyanine green and indicator dilution principle. Arterial blood flow and A and V concentrations of ammonia and amino acids will be measured before an oral load of BCAA (0.45 g BCAA/kg body weight) and after 1 and 3 hours. The metabolism of ammonia will also be estimated by means of 13N-NH3 PET scans. Hypothesis: BCAA increases the uptake of ammonia in muscle tissue and lowers arterial ammonia.