A patient with severe peripheral artery disease experiences increased blood viscosity in the lower limbs. Which mechanism explains why this increased viscosity diminishes the effectiveness of vasodilators?

💡 Explanation

Vasodilators often rely on endothelial nitric oxide release to induce smooth muscle relaxation and vasodilation; however, increased viscosity impairs the shear stress-mediated activation of endothelial nitric oxide synthase (eNOS), because blood flow is reduced. Therefore, vasodilation is less effective, rather than having direct smooth muscle or platelet activation issues.

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