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How chicks revealed Viagra protects fetal hearts

  • 30 March 2017

A component of the drug Viagra protects the heart of a growing fetus during problem pregnancies, according to new research authored by Caius Director of Studies in Medicine Professor Dino Giussani. The groundbreaking study, published in the Journal of Physiology, used chick embryos to measure the effect of the drug on fetal heart and circulation when oxygen is lower than normal.

One of the main complications of pregnancy is a problem with blood flow in the placenta which decreases oxygenation to the fetus and reduces its growth. This can happen during pre-eclampsia and other conditions. Sildenafil, the main component of Viagra, is a powerful vasodilator (a drug that opens blood vessels) that may protect fetal growth when a pregnancy is complicated by problems within the womb. Human clinical trials have recently been launched to see if the drug indeed helps prevent fetal growth restriction in adverse pregnancies. However, whether Sildenafil has effects other than on placental blood flow that may benefit or harms the fetus was until recently completely unknown.

In this study, funded by the British Heart Foundation and featured on the cover of the most recent issue from The Journal of Physiology, Dr Nozomi Itani and colleagues used the most unlikely of animal models to resolve this puzzle. Ingeniously, by using a chick embryo developing under lower than normal oxygen conditions, the scientists were able to isolate the direct effects of Sildenafil on the fetal heart and circulation independent of effects on the mother and the placenta. The work revealed that Sildenafil treatment directly protects the fetal cardiovascular system, and that the drug works by reducing oxidative stress - the same process that makes us age and the basis of antioxidant face creams to combat ageing of the skin. 

Lead author Professor Giussani, Professor of Developmental Cardiovascular Physiology & Medicine at Cambridge, said: "Sildenafil may be a good candidate drug to be used in human medicine to protect not only fetal growth but the developing heart and circulation of the baby in pregnancy complicated by reduced fetal oxygenation, such as during preeclampsia."

For more information, contact Communications Officer Lucy Ward: news@cai.cam.ac.uk.