A new research study has demonstrated, for the first time, how high blood sugar levels (hyperglycemia) influence the heart and blood pressure. According to the study, higher glycemia levels affect how blood vessels contract, making for stronger contractions than at normal physiological sugar levels.
Specifically, the researchers found that increasing glucose levels to those that might be found after a large meal altered vascular contraction.
The study was conducted by researchers at the Leicester University‘s Department of Cardiovascular Sciences, and led by Dr. Richard Rainbow, lecturer in Cardiovascular Cell Physiology. Titled “Distinct and complementary roles for α and β isoenzymes of protein kinase C in mediating vasoconstrictor responses to acutely elevated glucose,” it was published in the British Journal of Pharmacology.
The research team investigated the mechanism behind the narrowing of blood vessels by studying the impact of glucose on arterial myocytes, the cells that compose arterial tissue and blood vessels. It used electrophysiology and myography techniques, methods that allow muscle assessment by measuring its electrical properties.
Heart attacks result when coronary arteries become blocked, and prevent blood from reaching heart muscle. Research has shown that higher glucose levels can make such blockage more severe, leading to a higher risk of complications.
According to Dr. Rainbow, the study showed “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.”
“Here, we have identified [that] a known signaling 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. Protein kinase C (PKC) is a family of proteins responsible for the regulation of many cellular processes.
The study revealed that even people who are not diabetic can become hyperglycemic during a heart attack due to the stress response. Previous studies by the research team have also shown high glucose levels were an indicator of a poorer outcome following a heart attack. The presence of glucose can be damaging to the heart’s normal function, causing arrhythmia and hampering built-in protective mechanisms that might be activated in moments of stress.
The researchers conclude that the study provides “compelling evidence” of the possible therapeutic value of protein kinase C inhibitors in hyperglycemic patients with heart conditions.
“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,” Dr. Rainbow said.
