ADENYLATE-CYCLASE ACTIVITY IN MICRODISSECTED RAT-LIVER TISSUE - PERIPORTAL TO PERICENTRAL ACTIVITY GRADIENT

Adenylate cyclase activity was measured in microdissected samples from lyophilized cryostat sections of rat liver by means of an improved as say. Livers were obtained from adult Sprague-Dawley rats fasted for 22 hr. Adenylate cyclase activities, basal and those elicited by various agents, were determined in dissected samples from periportal and peri central regions of the classic liver lobule. In all samples, enzyme ac tivity was strongly stimulated by glucagon, cholera toxin, guanosine-5 '-O-(3-thiotriphosphate), sodium fluoride and forskolin. The beta-adre nergic agonist isoproterenol produced very weak, if any, enzyme stimul ation. Angiotensin II did not inhibit the activity elicited by lithium chloride and GTP at high concentrations, and pertussis toxin did not enhance the GTP-stimulated activity. We observed a periportal-to-peric entral gradient for basal and agent-stimulated activities.