"Knowing more about the effects of sildenafil on heart function will allow for safer evaluation of its use as a treatment for heart problems," says Kass. "Until now, it was widely thought that drugs like sildenafil had no effects on the human heart and that its only purpose was vasodilation in the penis and the lungs.

"Our results set the stage for further studies of sildenafil's immediate and long-term effects on the heart and its ability to modify other neurohormonal and stress stimuli, including adrenaline and hypertension," he adds.

While the precise biological actions of sildenafil in the heart are not fully understood, the drug is known to work by stopping the action of an enzyme, called phosphodiesterase 5 (PDE5A), the researcher says. This enzyme is involved in the breakdown of a key molecule, cyclic GMP, which helps control stresses and limit overgrowth in the heart. PDE5A is also the biological pathway blocked in the penis by sildenafil to prevent the relaxation of blood vessels and maintain erections.

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Contact: David March
dmarch1@jhmi.edu
410-955-1534
Johns Hopkins Medical Institutions
24-Oct-2005