Relationship between limb and muscle blood flow in man

: Raitakari M, Nuutila P, Ruotsalainen U, Teras M, Eronen E, Laine H, Raitakari OT, Iida H, Knuuti MJ, YkiJarvinen H

Publisher: CAMBRIDGE UNIV PRESS

: 1996

: Journal of Physiology

: JOURNAL OF PHYSIOLOGY-LONDON

: J PHYSIOL-LONDON

: 496

: 2

: 543

: 549

: 7

: 0022-3751

DOI: https://doi.org/10.1113/jphysiol.1996.sp021705

1. Since direct measurement of muscle blood flow in humans has been difficult, estimations of muscle flow have been made from measured total limb blood flow using a classic equation that predicts that the fraction of resting blood flow through muscle tissue decreases as total limb flow increases.2. We used positron emission tomography and O-15-labelled water to directly quantify resting muscle and total limb blood flow in cross-sections of the femoral region in twenty-eight normal subjects (age, 30 +/- 8 years; body mass index, 24.1 +/- 3.3 kg m(-2)) under conditions of constant environmental temperature of 22-23 degrees C.3. Muscle blood flow averaged 3.1 +/- 1.7 ml (100 ml muscle)(-1) min(-1) (range, 1.1-7.5 ml (100 ml muscle)(-1) min(-1)) and cross-sectional limb blood flow averaged 2.5 +/- 1.1 (100 ml limb)(-1) min(-1) (range, 1.0-4.8 ml (100 ml limb)(-1) min(-1)). A linear relationship was observed between limb and muscle blood flow, and a regression equation was calculated for estimation of muscle blood flow based on limb flow: muscle flow = (1.41 +/- 0.10)limb flow-(0.43 +/- 0.28). The slope of this equation was significantly greater than 1 (P < 0.001) indicating that the fraction of blood flow perfusing muscle tissue increases as a function of total limb flow.4. These data provide a new equation for estimation of resting muscle blood flow in normal subjects, and demonstrate that muscle blood flow is the primary determinant of resting blood flow in man.