A Novel Approach to Manage Heart Failure
DECEMBER 29, 2011 BY DR. MINAKSHI WELUKAR 0 COMMENT
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Sildenafil citrate, an active ingredient of Viagra is commonly used in treatment of erectile dysfunction or impotency. Now researchers identify that sildenafil may play a dynamic role in combating heart troubles.
According to study result published in the journal, Circulation, sildenafil increases the elasticity of stiffened cardiac walls in the heart failure cases. This is due to activation of an enzyme protein kinase G that causes the giant protein titin in the myocardial cells to relax.
In “Relax” study of the Heart Failure Network, Bochum’s researchers worked in collaboration with colleagues from the Mayo Clinic in Rochester (Minnesota). They studied dogs with diastolic heart failure, a condition characterised by stiff ventricles and hence unable to fill with blood adequately along with the efficacy of sildenafil in such cases.
Prof. Dr. Wolfgang Linke of the RUB Institute of Physiology said:
“We have developed a therapy in an animal model that, for the first time, also raises hopes for the successful treatment of patients”
What Is Heart Failure?
According to American Heart Association, heart failure is one of the most common reasons to visit hospital in people 65 years or above. In developed countries, nearly 2% of grownups suffer from heart failure. Heart failure is potentially life-threatening and high priced condition.
Congestive heart failure is the inability of the heart to supply enough oxygenated blood to various organs of the body. Patient can presents with shortness of breath, leg swelling, and exercise intolerance. Heart failure may be due to systolic failure or diastolic failure. In systolic heart failure heart muscle cannot pump sufficient blood out of the heart rightly, whereas in diastolic heart failure heart muscles are stiff and do not fill up with blood easily.
Role of Viagra in Heart Failure?
Sildenafil, an active constituent of Viagra, inhibits a specific enzyme known as phosphodiesterase 5 A. This prevents degradation of cGMP (Cyclic Guanosine Monophosphate), a type of a messenger substance and hence increases its concentration. The cGMP leads to activation of intracellular protein kinase G in response to the binding of membrane-impermeable peptide hormones to the external cell surface. The enzyme protein kinase G is attached to phosphate groups to certain proteins which lead to phosphorylation and causes blood vessels to relax. This vasodilator effect of sildenafil in corpus cavernosum is used to treat erectile dysfunction.
Researchers found that the cardiac muscle contains a protein ‘ titin ‘which, behave like a rubber bands and makes cardiac walls stiff. The titin molecules are also phosphorylated in exactly same way by sildenafil. Protein kinase G induced phosphorylation makes titin to relax and enhances cardiac walls elasticity. The effect occurs within minutes of administering the drug.
Dr. Linke added:
“If, for the first time, the drug is found to have a positive effect on heart failure, we would already have a molecular mechanism on hand to explain the effect.”
According to experts, most of heart failure hospitalization cases above 60 years are diastolic heart failure type. It is very well known that decreased distensibility of the cardiac walls is the root cause for the disease occurrence. Present medications are insufficient to treat this badly condition. In such cases Viagra have a beneficial role in alleviating the mortality and improving survival.
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