Nitric oxide helps pregnant women with hypertension

Sep 21 2006

Nitric oxide (NO) is best known as an air pollutant produced by vehicle emissions and power plants but for pregnant women it is a crucial compound required to avoid hypertension and pre-eclampsia.

Now researchers at the University of Warwick's Warwick Medical School have uncovered some of the secrets of what can interfere with the protecting properties of NO for pregnant women.

Pre-eclampsia affects 7-10% of all pregnancies. It causes high blood pressure and protein in the urine in its initial stages but can lead to fits and ultimately death. Its precise cause remains unknown. In severe forms of pre-eclampsia, particularly in early-onset cases that appear before the 34th week of gestation, the foetus suffers from increasing nutritional and respiratory problems, asphyxia and, ultimately, might die. Women who have had pre-eclampsia also seem to be at significantly increased risk of developing cardiovascular disease in later life. The disease is a major health burden worldwide.

Nitric oxide is a gas which is an important signalling molecule in humans. It is one of the few gaseous signalling molecules known and plays an important role in blood pressure control by opening up blood vessels. It is better known as an air pollutant produced by vehicle engines and power plants.

During pregnancy, nitric oxide levels maintain a healthy flow of blood to the baby. When NO levels in the placenta are reduced or the NO is blocked from doing its work the risk of pre-eclampsia can occur. Now researchers at the University of Warwick's Warwick Medical School have uncovered some of the secrets of what can interfere with the protecting properties of NO for pregnant women.

The Warwick Medical School researchers have managed to identify a complex range of problems that affect the way the NO works in the placenta during pre-eclampsia. When the pregnancy is compromised the placenta can also release a hormone called "corticotropin releasing hormone" (CRH - also known as the "stress" hormone). This hormone can directly influence NO production. The Warwick researchers have discovered that in pre-eclampsia there is a fault which does not allow this to occur. This then causes a cascade of signalling abnormalities through a number of protein receptors called GPCRs that prevent activation of the enzyme responsible for NO production.

The researchers also discovered that even if that part of the process works the placenta may still have restricted ability to produce NO in sufficient quantity.

This research has shed an immense amount of light on what can stop this crucial compound from protecting women and their unborn children from pre-eclampsia. Now the Warwick Medical School Researchers are seeking support for research that will target these discoveries with medical interventions that could resolve the problems and allow NO to perform its crucial role. The researchers first hope to target the faulty protein receptors which should activate the enzyme that releases NO.