The breakthrough study by the Canadian scientists has given fresh insights into the popular erectile dysfunction drug Viagra’s use for the treatment of heart problems.
Queens University Professor Donald Maurice, who led the study, says they've found shaping one enzyme might lead to using Viagra, which is also used to treat pulmonary
define hypertension, to help prevent heart attacks and strokes.
“As scientists, we're excited about this discovery because it's a fundamentally new approach to regulating what enzymes do in cells," said Maurice, who is a professor of Pharmacology and Toxicology. "The fact that it also offers a potentially novel use of a drug already widely in use for other applications is an unexpected bonus."
The Queen’s researchers said the drug inhibits an enzyme called Phosphodiesterase Type 5 Inhibitor, or PDE5 inhibitors that regulate the activity of platelets: small blood cells needed for normal blood clotting.
According to them, patients who have drug-eluting stents inserted into diseased arteries to prop them open are at greater risk of developing the heart problems. Their platelets sometimes bind to the stent, aggrandizing the chance of the blood clotting inside the stent which would result in serious and sometimes fatal heart attack.
Viagra has been shown to inhibit PDE5, said Lindsay Wilson, a PhD student in Pathology and molecular medicine and first author of the study, but it has not been possible so far to isolate the small “pool” of activity within the cell where it occurs.
In their study, the Queen’s scientists have shown that within each cell there are two different pools of the PDE5 enzyme, but that only one of them regulates platelet activation.
“Understanding how the cell works should allow us to affect the activity of enzymes in one neighborhood – and leave alone their ‘identical twins’ in a different neighborhood in that cell,” Wilson said. "The idea is to use a PDE5 inhibitor such as Viagra to selectively inhibit platelet function. We now know that not all the enzymes in the cell are doing the same job. Just like in real estate, it’s all about the location!"
The findings of the latest study appear in the online early edition of the Proceedings of the National Academy of Sciences.
Viagra, developed by the pharmaceutical company Pfizer, is mainly used to treat male erectile dysfunction (impotency) and pulmonary arterial hypertension (PAH). Drugs like tadalafil (Cialis) and vardenafil (Levitra) also perform the similar functions.
Its common side effects include sneezing, headache, flushing, dyspepsia, prolonged erections, palpitations and photophobia. Visual changes including blurring of vision and a curious bluish tinge have also been reported.
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