Effects of Reduced Aldosterone Secretion on Hypertension Development in the Spontaneously Hypertensive Rat (SHR) as Measured by Remote Monitoring

Hypertension, also known as high blood pressure, is a well known cause of cardiovascular disease, the leading cause of death in the United States. The cause of hypertension is poorly understood, but an increase in sodium retention by the kidneys, causing expansion in blood volume and a rise in blood pressure, is a contributing factor. The hormone aldosterone is produced in the outermost layer of the adrenal gland and increases the amount of sodium retained by the kidneys and may be a contributing factor to hypertension development. Eliminating aldosterone by removing both adrenal glands results in death of the animal.However, the effect of surgically reducing aldosterone in young hypertensive rats has not been investigated as a means to prevent development, or reduce the severity of hypertension. This study used an adrenal freezing procedure that reduced the amount of aldosterone secreted to approximately 30% of normal. The rats were studied using a remote monitoring device that was implanted in the femoral artery (in the hind leg). This system allowed the recording of blood pressure and heart rate while the rat was freely moving in its cage. The development of high blood pressure was compared between the adrenal frozen rats and the control rats. We expected a reduction in blood pressure in the adrenal frozen rats, indicating that aldosterone has a significant role in the development of hypertension. This information may lead to new measures to prevent hypertension in genetically predisposed individuals.