ABSTRACT

Adenylyl cyclase is a family of enzymes that synthesize cAMP. The distributions of messenger ribonucleic acid encoding specific adenylyl cyclase isoforms within different brain regions has been extensively characterized by in situ hybridization. Measurements of adenylyl cyclase activity in neural tissues have traditionally used broken cell preparations which allow selective activation of individual components of the receptor-G protein-adenylyl cyclase cascade. Adenylyl cyclase activity is commonly measured under basal conditions and in response to activators effective at various levels of the receptor-G protein-adenylyl cyclase cascade. Sequential column chromatography over dowex and alumina resins is a procedure for the retention of unmetabolized P-α-ATP within the resins and the elution of newly synthesized P-cAMP into scintillation vials to measure incorporated P. A reasonable starting point is to prepare a cellular homogenate that is enriched for the plasma membrane fraction by first lysing the tissue or cultured cells by high-speed cutting blades, Potter-Elvehjem tissue grinder, or nitrogen cavitation.