Lead activates calmodulin sensitive processes.

The effect of lead on two calcium sensitive processes was determined. Micromolar concentrations of lead successfully replaced calcium in the activation of calmodulin-sensitive phosphodiesterase and in the promotion of potassium loss from erythrocytes. Both actions of lead were blocked by trifluoperazine--an inhibitor of calmodulin function. We propose that some of the toxic effects of lead may be explained by its interaction with calmodulin.