How our fight-flight response affects blood vessels

Mechanisms leading to an impairment of vascular homeostasis during acute stress: interaction between sympathetic activity and neuronal nitric oxide synthase

Acute psychological stress is thought to be able to precipitate a cardiovascular event, like a heart attack. The release of nitric oxide, a molecule of key importance in cardiovascular health is strongly influenced by stress and may protect against stress induced heart attacks. This is because nitric oxide relaxes blood vessels, increasing blood flow. But nitric oxide release is abnormal in some people, particularly those with high blood pressure, predisposing them to stress induced heart attacks. Professor Philip Chowienczyk and colleagues at King’s College London will study if the sympathetic nervous system, which is responsible for our fight-or-flight response, is linked to this reduced nitric oxide response to stress, because the sympathetic nerves oppose the production of neuronal nitric oxide synthase – the enzyme that makes nitric oxide. As nitric oxide relaxes blood vessels, a reduction in its levels causes blood vessels to contract and can increase the risk of a heart attack. This research should help identify new ways to reduce the risk of stress induced heart attacks.