To assess the ability of the liver to remove immunoreactive arginine vasopressin (AVP) from the circulation and to determine the effect of certain metabolic factors on the process, a study was carried out with rat livers perfused at 37 C with an oxygenated albumin--electrolyte solution containing AVP (117 +/- 4.5 muU/ml). In controls, the hepatic clearance of AVP was 795 +/- 120 microliter/min (SEM). The addition of AVP in concentrations up to 9029 microU/ml, perfusion with a glucose-free medium, or perfusion without oxygen did not significantly alter the hepatic clearance of AVP. However, perfusion with cold medium (11 C) significantly altered AVP removal in that initially AVP removal increased, while later on AVP removal became completely inhibited. This phenomenon may possibly be a consequence of a cold-induced increase in hepatic AVP trapping which is rapidly saturated due to a cold-induced depression of AVP transport and degradation. Support for this thesis was provided by finding that high AVP concentrations depressed the cold-endhancing removal phase.