Competitive binding assay for drugs that interfere with calmodulin function.

A direct 125I-calmodulin-binding system utilizing a particulate cytoskeletal preparation of the neuronal calmodulin-dependent protein kinase type II provides a simple, rapid filtration-based method for assessing anti-calmodulin drug activity. The binding assay avoids potential artifacts due to direct drug effects on the standard phosphodiesterase enzyme assay while obtaining comparable IC50 values for a spectrum of drugs. It also provides a tool to probe mechanisms of action of putative anticalmodulin agents which may help elucidate selective pharmacologic modifications of pathophysiological processes.