Reactive Hyperemia in Human Forearm Vessels

Background The role of nitric oxide (NO) in reactive hyperemia (RH) is not well known. We investigated whether NO plays a role in RH in human forearm vessels by examining the effects of N0-monomethyl-L-arginine (L-NMMA), a blocker of NO synthesis, on reactive hyperemic flow. Methods and Results Forearm blood flow (FBF) was measured by strain-gauge plethysmography with a venous occlusion technique. The left brachial artery was cannulated for drug infusion and direct measurement of arterial pressure. To produce RH, blood flow to the forearm was prevented by inflation of a cuff on the upper arm to suprasystolic pressure for intervals of 3 and 10 minutes. After the release of arterial occlusion (AO), FBF was measured every 15 seconds for 3 minutes. Resting FBF was 4.3+0.3 mL* min 100 mLbefore 3 minutes of AO and 4.1+0.6 mL* min'-* 100 mL`1 before 10 minutes of AO. FBF increased to 32.3± 1.9 and 38.2+3.1 mLmin'* 100 mL-1 immediately after 3 and 10