A recent British Heart Foundation survey showed that cardiovascular diseases (CVD) such as angina, heart attack, heart failure, and stroke cause one quarter of all deaths in the UK. CVD also costs the UK over £29 billion a year in healthcare plus loss of work days. These figures caused by CVD numbers will increase as the number of elderly people in our population continues to grow. It is clear we need new drugs to treat CVD. A decrease in the diameter of the open space or 'lumen' of our blood vessels produces high blood pressure and reduces blood flowing to our organs - both these problems increase the risk of us developing CVD. It is known that when muscle cells found in the walls of blood vessels contract too much they decrease the lumen diameter. Our research focuses on understanding what causes these muscle cells to contract too much. By knowing more about these muscle cells and how they control lumen diameter of blood vessels we will help develop new drugs to treat CVD. The amount of calcium inside these muscle cells is highly associated with contraction of these muscle cells and therefore the lumen diameter of blood vessels. When calcium levels increase too much it causes the muscle cells to excessively contract and reduce the lumen of blood vessels. We investigate proteins, called TRPC1, which form specialised holes called channels that are found in the membrane that surrounds muscle cells. When these TRPC1 channels are opened they allow calcium to be transported into muscle cells. If we could find a way to reduce TRPC1 channels from opening, we could reduce the amount of calcium entering muscle cells, which would reduce contraction of these cells, and prevent the diameter of blood vessels from becoming too small: this would be an excellent strategy for treating CVD. In this proposal, we plan to investigate what causes TRPC1 channels to open and let calcium into muscle cells using the blood vessels of mice, which are an excellent animal species for allowing us to understand what happens in human blood vessels. Our research will greatly advance our knowledge on TRPC1 channels and on how the lumen diameter of blood vessels may be controlled. This will directly help in the development of new treatments for CVD. TRPC1 channels also control the level of calcium in cells from other parts of the body such as the brain, kidneys and lungs. Therefore our studies will also help understand diseases involving a variety of other body systems.