Adenylate cyclase activity in corpus striatum of rats with porto-caval anastomosis.

Altered catecholamine receptor sites within the striatum have been proposed to be an important pathogenetic factor in hepatic and porto-systemic encephalopathy and coma. The unstimulated, fluoride-, norepinephrine- and dopamine-stimulated adenylate cyclase activity were measured in the corpus striatum of rats with a four weeks old end-to-side porto-caval anastomosis. There was no difference in unstimulated, fluoride- or hormone-stimulated adenylate cyclase activity between porto-caval shunted and sham-operated rats. The in vitro dose-response curves of norepinephrine and dopamine were similar in both groups of animals. Half-maximum and maximum stimulation were achieved in shunted and sham-operated rats by identical concentrations of norepinephrine and dopamine, respectively. The results indicate that neither changes in unstimulated adenylate cyclase activity nor changes in the response of adenylate cyclase activity to fluoride, norepinephrine and dopamine had developed in the rats at the stage studied.