Muscle contraction induced arterial shear stress increases endothelial nitric oxide synthase phosphorylation in humans.
Level 3 - non-randomized controlled study
Non-randomized controlled physiological intervention study
PubMed 28801524 · doi:10.1152/ajpheart.00282.2017
What was done
Thirteen healthy young men were assigned to an exercise protocol (n = 7, mean age 25 ± 1 years) or a non-exercising time-control group (n = 6, mean age 24 ± 1 years). The exercise group completed twenty 3-minute bouts of rhythmic forearm exercise at 20% of maximum with 3-minute rest intervals over 2 hours. Endothelial cells were collected directly from the brachial artery using sterile J-wires through an arterial catheter at baseline and after the 2-hour period. Protein expression of total endothelial nitric oxide synthase (eNOS) and phosphorylated eNOS at Ser1177 (p-eNOS Ser1177) was quantified via immunofluorescence.
What was found
Brachial artery mean shear rate remained elevated throughout the 2-hour exercise protocol compared with baseline and time controls (P < 0.001). p-eNOS Ser1177 expression increased 57% in endothelial cells from the exercise group (0.06 ± 0.01 vs. 0.10 ± 0.02 arbitrary units [au], P = 0.02), with no change in the time-control group (0.08 ± 0.01 vs. 0.07 ± 0.01 au, P = 0.72). Total eNOS expression did not change in the exercise group (0.13 ± 0.04 vs. 0.12 ± 0.03 au) or the time-control group (0.12 ± 0.03 vs. 0.11 ± 0.03 au; P > 0.05 for both).
Why it matters
This study provides direct in vivo evidence in humans that acute elevations in conduit artery shear stress during exercise induce posttranslational activation of eNOS via Ser1177 phosphorylation in endothelial cells.
Limits
The sample size was very small (13 total participants) and non-randomized. The study examined only young, healthy men, precluding generalization to women, older adults, or clinical populations with endothelial dysfunction. Only acute responses over a single 2-hour window were measured.
Cited by
- supports Increased blood flow velocity from walking stimulates the endothelial lining of blood vessels to produce nitric oxide.