London | An increased level of sugar in blood can affect the contraction of blood vessels, with potentially dangerous effects on the heart and blood pressure, a new study has warned. Researchers at the University of Leicester in the UK have shown that blood vessels contract more strongly at raised glucose levels than at ‘normal physiological’ levels. Blood vessels contract and relax to control blood pressure. The more contracted the blood vessels are, the higher the blood pressure. Using electrophysiology and myography techniques to examine the impact of glucose on arterial myocytes, cells that make up the tissue of our blood vessels, the researchers have identified a mechanism that controls the narrowing of blood vessels. Heart attacks occur when a coronary artery, which provides the blood to the heart muscle to give the required nutrients and oxygen, are blocked.
High glucose at the time of heart attack could make this block more severe by causing the blood vessel to contract, leading to a higher risk of complications. We have shown that the amount of sugar, or glucose, in the blood changes the behaviour of blood vessels making them contract more than normal. This could result in higher blood pressure, or could reduce the amount of blood that flows through vital organs, said Richard Rainbow from University of Leicester. Here, we have identified a known signalling protein family, protein kinase C, is a key part of this enhanced contractile response, and have also shown in our experiments that we can restore the normal level of contractile response, and reverse the effects on the heart, with inhibitors of these proteins, he added. A large number of people who suffer a heart attack will have high glucose due to the ‘stress response.’
This means that even people who are not diabetic may become hyperglycaemic during a heart attack, researchers said. The findings provides a potential therapeutic target for improving outcomes following a heart attack or stroke. Our studies show that glucose has an important physiological effect on the normal functioning of the cardiovascular system. Increases in blood sugar to pathophysiological levels cause marked changes in normal blood vessel and cardiac muscle behaviour that could be life-threatening if left untreated, Rainbow said. Our data show a clear glucose-induced potentiation of contraction in blood vessels. Targeting the specific types of protein kinase C that we’ve shown to be involved in this can provide a novel therapeutic route for improving outcome in ischaemic diseases, such as heart attack or stroke, he added.
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