Rats were given intravenous injections of cyclic [3H]AMP and the disappearance of radioactivity from plasma and its appearance in bile were followed. Livers were removed and the cyclic [3H]AMP content was measured. The binding of radioactivity to soluble proteins was measured after preparations of a cytoplasmic fraction. Experiments in vitro to determine the ability of hepatic cytoplasmic proteins to bind cyclic [3H]AMP were also carried out. A role for cytoplasmic proteins in the clearance of cyclic AMP from plasma is discounted.
