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Postischemic vasodilation in human forearm is dependent on endothelium-derived nitric oxide
I T Meredith1, K E Currie, T J Anderson
1Vascular Medicine and Atherosclerosis Unit, Brigham and Women's Hospital, Boston, Massachusetts, USA.
The American Journal of Physiology
|April 1, 1996
Summary
Endothelium-derived nitric oxide (NO) is crucial for reactive hyperemia, the increase in blood flow after a temporary blockage. Inhibiting NO significantly reduced this response, highlighting its role in vascular regulation during metabolic changes.
Area of Science:
- Cardiovascular Physiology
- Vascular Biology
- Nitric Oxide Research
Background:
- Endothelium-derived nitric oxide (NO) influences basal vascular tone.
- Its role in regulating blood flow during metabolic demand changes is not fully understood.
Purpose of the Study:
- To investigate the contribution of endothelium-derived NO to reactive hyperemia in the human forearm.
- To assess the impact of NO synthase inhibition on post-ischemic blood flow regulation.
Main Methods:
- Utilized NG-monomethyl-L-arginine (L-NMMA), a nitric oxide synthase inhibitor.
- Induced forearm ischemia using a suprasystolic cuff for 5 minutes.
- Measured hyperemic flow post-occlusion with venous occlusion strain-gauge plethysmography.
- Assessed L-NMMA efficacy via dose-response to acetylcholine.
Main Results:
- L-NMMA significantly reduced the dose-response to acetylcholine, confirming NO blockade.
- Peak hyperemic flow decreased by 16% after L-NMMA administration.
- Total hyperemia was reduced by 17% at 1 minute and 23% at 5 minutes post-ischemia.
Conclusions:
- Endothelium-derived nitric oxide plays a significant role in reactive hyperemia.
- NO contributes to maintaining the hyperemic response following ischemia in the forearm.