Abstract

In the past Hawthorn leaves, berries and flowers have been used in Asia to treat hypertension (high blood pressure) and other cardiovascular diseases. It is hypothesized that the Hawthorn extract acts as a vasodilator increasing the size of the lumen of blood vessels by relaxing the smooth muscle. This occurs by decreasing the amount of calcium that is present in the cytosol by either increasing the effectiveness of the Ca²⁺ -ATPase pump or by altering the Na⁺ -Ca²⁺ antiport exchanger. With this decrease in cytosolic calcium the calcium unbinds from CaM causing the enzyme myosin phosphatase to remove phosphate from the myosin thus causing the smooth muscle to relax. The commercially available Hawthorn extract used in these studies did not have a significant effect on coronary or pulmonary arteries. The denuded and intact LADs did have a significant relaxation at higher concentrations which was likely due to the ethanol that was used in the formulation of the extract.