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Mental stress opposes endothelium-dependent vasodilation in young healthy individuals
Insights
Mental stress from arithmetic tasks impairs endothelium-dependent vasodilation, affecting blood flow regulation. Other stressors like cold pressor and isometric handgrip tests cause broader, less specific vasodilation changes.
Area of Science:
- Cardiovascular Physiology
- Endothelial Function
- Stress Physiology
Background:
- Mental stress is a known trigger for myocardial ischemia in coronary heart disease patients.
- The endothelium plays a crucial role in regulating vascular tone and blood flow, particularly during stress responses.
Purpose of the Study:
- To investigate the role of the endothelium in blood flow regulation during different types of mental stress.
- To differentiate the effects of mental arithmetic, cold pressor, and isometric handgrip tests on endothelium-dependent and endothelium-independent vasodilation.
Main Methods:
- Utilized venous occlusion plethysmography in 10 healthy young volunteers.
- Measured forearm vascular resistance during intraarterial infusions of methacholine (endothelium-dependent vasodilation) and sodium nitroprusside (endothelium-independent vasodilation).
- Assessed responses at rest and during mental arithmetic test, cold pressor test, and isometric handgrip test.
Main Results:
- Mental arithmetic test significantly increased forearm vascular resistance during methacholine infusion, indicating impaired endothelium-dependent vasodilation.
- Cold pressor and isometric handgrip tests increased forearm vascular resistance during both methacholine and sodium nitroprusside infusions, suggesting a general attenuation of vasodilation.
- The ratio of sodium nitroprusside to methacholine forearm vascular resistance, an index of endothelial function, was significantly impaired only during the mental arithmetic test.
Conclusions:
- Mental stress induced by arithmetic tasks selectively impairs endothelium-dependent vasodilation in healthy young individuals.
- Cold pressor and isometric handgrip tests induce a more generalized reduction in vasodilatory capacity.
- These findings highlight the specific impact of cognitive stress on endothelial function and vascular regulation.
Abstract:
Mental stress has been shown to induce myocardial ischemia in people with coronary heart disease (CHD), both in the laboratory and in daily life. In order to investigate the role of the endothelium in the regulation of blood flow during stress, the endothelium-dependent (EDV) and endothelium-independent (EIDV) vasodilation was examined in the forearms of healthy people during a mental arithmetic test (MAT), a cold pressor test (CP) and an isometric handgrip test (ISO). A total of 10 young healthy volunteers (four men and six women, aged 20-25 years) underwent measurements of forearm vascular resistance (FVR) during local intraarterial infusions of methacholine (MCh; inducing EDV) and sodium nitroprusside (SNP; inducing EIDV) at rest and during the different forms of stress by the use of venous occlusion plethysmography. MAT induced a significant increase in FVR during MCh infusion (4 microg/min, from 3.5 +/- 0.7 at rest to 4.2 +/- 1.4 mmHg/ml per min per 100 ml tissue during MAT; p < 0.01), while FVR during SNP infusion was unchanged by MAT. CP induced a significant increase in FVR during infusions with both MCh and SNP compared to resting levels (p < 0.01 for both), while ISO induced a significant increase in FVR during MCh infusion (p < 0.05) and a smaller increase in FVR during SNP infusion. When the SNP to MCh FVR ratio was used as an index of endothelial function, only MAT impaired endothelial function significantly (p < 0.01). In conclusion, mental stress induced by an arithmetic task selectively opposed EDV in the forearms of young healthy people, while cold pressor and isometric handgrip tests induced a more general attenuation in vasodilatation.