The Effects of Electrical Shock Stress on Blood Fluidity in Rats

It is well known that many stressors affect the circulatory system, including the heart and blood vessels, through neuronal and humoral mechanisms. However, the effect of stressors on blood fluidity –one of the most important factors in the circulatory system– is unclear. According to Poiseuille's law, reduced blood fluidity increases blood vessel resistance and enhances blood coagulation. Reduced blood fluidity also increases blood pressure and the risk of thrombosis. Therefore, this study examined the effects of electrical shock (ES) stress on blood fluidity in male Wistar rats using a microchannel array flow analyzer, which mimics capillary vessels. We found that blood fluidity was reduced following ES stress. In blood treated with the anticoagulants heparin and EDTA, the reduction in blood fluidity was greater in heparinized blood than in EDTA-treated blood. When the α-blocker phentolamine was used, blood fluidity was restored in heparin-treated but not EDTA-treated blood. Since heparin blocks blood coagulation, but EDTA blocks both blood coagulation and platelet agglutination, this result indicates that ES stress might reduce blood fluidity by affecting platelet agglutination. In addition, ES stress might reduce blood fluidity, at least partly, through the adrenergic system.