Ionic conductances in arterioles modulated by endothelium-derived factors

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The endothelial cells which form the inside lining of blood vessels can release a number of chemicals, some of which can relax the muscle in the wall of the blood vessels, while other chemicals can make the blood vessels contract. The correct balance between the contracting chemicals and the relaxing chemicals is essential for normal healthy functioning of the vessels and therefore proper blood flow through the organs of the body, and for the maintenance of normal blood pressure. If an imbalance occurs, such as a decrease in the effectiveness of the relaxing chemicals, then the muscle in the wall of the blood vessels tends to be more contracted, and this may result in decreased blood flow and possibly increased blood pressure. Such imbalances may underlie the vascular complications of diabetes, Raynaud's Phenomenon and essential hypertension. In a recent study on the effects of relaxing chemicals released from the endothelial cells, we have discovered the effects of a chemical which can cause blood vessels to contract. The chemical identity of this factor and the mechanisms by which it causes contraction are not known. Since excess activity of this chemical would tend to contract the blood vessels and therefore raise blood pressure, it is important to determine the chemical identity of this substance, and to determine how it causes contraction. The eventual development of drugs to inhibit the actions of this chemical may be a possible means for treating some diseases of the vascular system. This study is aimed at determining how this factor causes the blood vessels to contract, and takes the first steps towards determining its identity.