Lee Stoner1, Kevin K McCully. 1. Department of Kinesiology, University of Georgia, Ramsey Center, Athens, GA 30602, USA.
Abstract
BACKGROUND: To determine whether peak and time-integrated shear rates independently predict flow-mediated dilation (FMD). METHODS: Eleven physically active (25 ± 5 years old) male subjects were tested. FMD was defined as the shear rate-diameter relationship. Hierarchical linear modeling was used to estimate brachial artery diameter change with repeated measures of shear rate nested within each subject. Two models were tested: 1) FMD was induced using ischemia-induced hyperemia (2, 4, 6, and 10 minutes); and 2) FMD was induced following transient (ischemia) and steady-state (forearm heating and handgrip exercise) increases in shear rate. For both models we determined whether peak, in addition to time-integrated shear rates, explained a significant portion of variation for diameter change. RESULTS: Model 1: Time integrated shear rates explained most of the variation for diameter change. However, peak shear rate explained an additional significant portion of variation. Model 2: The transient condition resulted in significantly (p = 0.012) smaller diameter change per shear rate change than the steady-state condition. However, when specifying peak shear rate as a covariate, the difference between conditions became nonsignificant (p = 0.138). CONCLUSIONS: Peak and time-integrated shear rates independently predict FMD. Future studies using the FMD test should consider both parameters.
BACKGROUND: To determine whether peak and time-integrated shear rates independently predict flow-mediated dilation (FMD). METHODS: Eleven physically active (25 ± 5 years old) male subjects were tested. FMD was defined as the shear rate-diameter relationship. Hierarchical linear modeling was used to estimate brachial artery diameter change with repeated measures of shear rate nested within each subject. Two models were tested: 1) FMD was induced using ischemia-induced hyperemia (2, 4, 6, and 10 minutes); and 2) FMD was induced following transient (ischemia) and steady-state (forearm heating and handgrip exercise) increases in shear rate. For both models we determined whether peak, in addition to time-integrated shear rates, explained a significant portion of variation for diameter change. RESULTS: Model 1: Time integrated shear rates explained most of the variation for diameter change. However, peak shear rate explained an additional significant portion of variation. Model 2: The transient condition resulted in significantly (p = 0.012) smaller diameter change per shear rate change than the steady-state condition. However, when specifying peak shear rate as a covariate, the difference between conditions became nonsignificant (p = 0.138). CONCLUSIONS: Peak and time-integrated shear rates independently predict FMD. Future studies using the FMD test should consider both parameters.
Authors: Lee Stoner; Keeron Stone; Gabriel Zieff; EriK D Hanson; Daniel Credeur; James Faulkner; Anna Kucharska-Newton; Simon Fryer Journal: J Hum Hypertens Date: 2019-02-25 Impact factor: 3.012
Authors: Avinash Chandran; Derek W Brown; Gabriel H Zieff; Zachary Y Kerr; Daniel Credeur; Lee Stoner Journal: Hypertens Res Date: 2021-01-28 Impact factor: 3.872
Authors: Lee Stoner; Keeron Stone; Gabriel Zieff; Jade Blackwell; Jake Diana; Daniel P Credeur; Craig Paterson; Simon Fryer Journal: Vasc Med Date: 2020-06-03 Impact factor: 3.239