Phosphodiesterase 5 inhibition-induced coronary vasodilation is reduced after myocardial infarction.

The balance between the production and removal of cGMP in coronary vascular smooth muscle is of critical importance in determining coronary vasomotor tone and thus in the regulation of coronary blood flow. cGMP production by soluble guanylyl cyclase is activated by nitric oxide (NO), whereas cGMP breakdown occurs through phosphodiesterase 5 (PDE5). We hypothesized that myocardial infarction (MI) alters the balance between the production and removal of cGMP in the coronary vasculature and thereby alters the control of coronary vasomotor tone.