Question
With respect to peripheral vascular disease, all of the following statements are true except:
| A. |
Ankle brachial index < 0.5 indicates critical limb ischemia
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| B. |
The ankle-brachial index is different at rest than that during exercise
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| C. |
L-arginine is useful for providing endothelium-independent vasorelaxation
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| D. |
Smoking has a greater association with peripheral vascular disease than coronary vascular disease
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Show Answer
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Correct Answer » C
Explanation
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Ans. c
L-arginine serves as a substrate for endothelial nitric oxide synthase (eNOS), facilitating endothelium-dependent nitric oxide (NO) production.
– NO synthesized via eNOS diffuses to vascular smooth muscle, activating guanylate cyclase and causing vasorelaxation.
– Therefore, L-arginine enhances endothelium-dependent vasodilation rather than acting directly on smooth muscle independently of the endothelium.
– Endothelium-independent vasorelaxation is mediated by agents that directly release NO or act on vascular smooth muscle, e.g., nitroprusside or calcium channel blockers.
