Studies on the cellular mechanisms of action of positive and negative inotropic agents.

We have reviewed the mechanism by which drugs that elevate cyclic AMP level modify myocardial contractility. We have presented preliminary evidence about the mechanism by which muscarinic agonists antagonize the effects of these drugs. Finally, we suggest that the protein phosphorylation experiments, particularly if done in dispersed myocytes, could be an efficient and cost-effective method of screening drugs which may act by elevating intracellular levels of cyclic AMP.