High blood pressure causes inactivation of nitric oxide, a hormone involved in blood pressure control which worsens the problem. If high blood pressure is left untreated, it does not stay at one elevated level, but tends to spiral out of control. According to the researchers at the University of Texas, this study was conducted on rats and found that nitric oxide, which helps control blood pressure by dilating blood vessels, is inactivated by increasing blood pressure.
As pressure increases, molecules called free radicals and reactive oxygen species cause cellular damage and inactivate nitric oxide, causing blood pressure to keep rising. As blood pressure continues to rise, more nitric oxide is inactivated, causing pressure to rise even higher.
According to researchers, while the initial causes of high blood pressure are diverse and in many cases unclear, this study shows the importance of making sure high blood pressure is always controlled and may provide greater understanding of the method. The team showed previously that increased free radical activity plays an important role in all cases of high blood pressure.
They further showed that increased levels of free radicals by themselves can cause hypertension. Harmful levels of free radicals are often reduced by certain antioxidants, including Vitamin E and other chemicals found in food. In this study, the researchers asked whether hypertension itself can increase this free radical production, using rats that had high blood pressure in the front half of the body and normal pressure in the rear half. The rats' front halves showed significant increases in a chemical called nitrotyrosine, a product of nitric oxide inactivation by reactive oxygen species.