In this study, radioligand binding analysis was used to quantitatively measure the concentration and affinity of alpha-1 adrenergic receptor in the liver of Wistar rats during the process of CCl4-induced liver cirrhosis. It was found that compared with normal controls, the maximal binding capacity (Bmax) of alpha-1 adrenergic receptor in the liver of 13 pre-cirrhotic rats decreased from 132.8 +/- 25.0fmol/mg to 96.9 +/-20.8fmol/mg of protein (P < 0.01) with increased dissociation constant (Kd, from 0.1633 +/- 0.0322nM to 0.3079 +/- 0.0786nM, P < 0.01). The Bmax in 20 cirrhotic rats decreased significantly from 132.8 +/- 25.0fmol/mg to 71.9 +/- 17.7fmol/mg of protein (P < 0.01), while Kd values increased from 0.1633 +/- 0.0322nM to 0.4012 +/- 0.0965nM (P < 0.01). These findings indicate that the decrease of binding capacity and affinity of alpha adrenergic receptor may play a role in the disturbances of metabolism of catecholamine often seen in some cirrhotic patients and have implications in the pathogenesis of portal hypertension.