Although Sildenafil citrate has been primarily used to treat erectile disfunction, this chemical also has health benefits for the heart.
When Sildenafil was tested on mice, it had the effect of reversing the long term damage to the heart caused by chronic hypertension. The way that Sildenafil citrate works to maintain an erection is to expand genital blood vessels that carry the blood supply to the penis when aroused. In the same way, Sildenafil can benefit the heart to treat pulmonary hypertension.
By dilating the blood vessels, Sildenafil causes a drop in blood pressure required to pump blood through the body.
While conducting experiments on mice, researchers realized that sildenafil was able to stop the short term effects of hormonal stress and reverse the long term damage on the heart muscle. The effects of heart failure and cardiac hypertrophy were also improved by sildenafil in mouse experiments, although this effect was not tested on human subjects.
To prove its effectiveness in humans, thirty five men and women participated in the John Hopkins study. In this test, volunteer participants took an injection of dobutamine, a chemical that increases the heart rate and contraction of the heart muscle. The heart rates of the participants increased by 150%. The volunteers were divided into two groups, where one group took sildenafil and the second group took a placebo. Then a second dose of dobutamine was administered to both groups. The first group taking sildenafil experienced a drop of 50% in heart rate and heart contraction, while the second group had an increase of 150% more.
Because this study was so successful, it sparked greater interest in researching the short term and long term effects of sildenafil on the heart and additional benefits to using this medication. Although research on this drug is still being conducted, researchers have learned that sildenafil stops the action of the enzyme phosphodiesterase 5 (PDE5A) from breaking down cyclic GMP, which helps to control stress and hypertrophy in the heart.