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Figure 2 Alternative interpretations of the results of clinical trials of beta-adrenergic receptor agonists and phosphodiesterase-3 inhibitors. The "conventional" interpretation is that increasing intracellular cyclic adenosine monophosphate (cAMP) content causes a short-term increase in contractility that causes a reduction in long-term survival. The alternative interpretation proposed herein is that the increase in intracellular cAMP content may increase contractility and increase mortality through separate mechanisms.