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Muscle capillary blood flow kinetics estimated from pulmonary O2 uptake and near-infrared spectroscopy.
- Source :
-
Journal of applied physiology (Bethesda, Md. : 1985) [J Appl Physiol (1985)] 2005 May; Vol. 98 (5), pp. 1820-8. Date of Electronic Publication: 2005 Jan 07. - Publication Year :
- 2005
-
Abstract
- The near-infrared spectroscopy (NIRS) signal (deoxyhemoglobin concentration; [HHb]) reflects the dynamic balance between muscle capillary blood flow (Q(cap)) and muscle O(2) uptake (Vo(2)(m)) in the microcirculation. The purposes of the present study were to estimate the time course of Q(cap) from the kinetics of the primary component of pulmonary O(2) uptake (Vo(2)(p)) and [HHb] throughout exercise, and compare the Q(cap) kinetics with the Vo(2)(p) kinetics. Nine subjects performed moderate- (M; below lactate threshold) and heavy-intensity (H, above lactate threshold) constant-work-rate tests. Vo(2)(p) (l/min) was measured breath by breath, and [HHb] (muM) was measured by NIRS during the tests. The time course of Q(cap) was estimated from the rearrangement of the Fick equation [Q(cap) = Vo(2)(m)/(a-v)O(2), where (a-v)O(2) is arteriovenous O(2) difference] using Vo(2)(p) (primary component) and [HHb] as proxies of Vo(2)(m) and (a-v)O(2), respectively. The kinetics of [HHb] [time constant (tau) + time delay [HHb]; M = 17.8 +/- 2.3 s and H = 13.7 +/- 1.4 s] were significantly (P < 0.001) faster than the kinetics of Vo(2) [tau of primary component (tau(P)); M = 25.5 +/- 8.8 s and H = 25.6 +/- 7.2 s] and Q(cap) [mean response time (MRT); M = 25.4 +/- 9.1 s and H = 25.7 +/- 7.7 s]. However, there was no significant difference between MRT of Q(cap) and tau(P)-Vo(2) for both intensities (P = 0.99), and these parameters were significantly correlated (M and H; r = 0.99; P < 0.001). In conclusion, we have proposed a new method to noninvasively approximate Q(cap) kinetics in humans during exercise. The resulting overall Q(cap) kinetics appeared to be tightly coupled to the temporal profile of Vo(2)(m).
- Subjects :
- Adult
Blood Flow Velocity physiology
Capillaries metabolism
Female
Humans
Male
Microcirculation metabolism
Regional Blood Flow physiology
Exercise physiology
Muscle, Skeletal blood supply
Muscle, Skeletal metabolism
Pulmonary Gas Exchange physiology
Pulmonary Ventilation physiology
Spectroscopy, Near-Infrared methods
Subjects
Details
- Language :
- English
- ISSN :
- 8750-7587
- Volume :
- 98
- Issue :
- 5
- Database :
- MEDLINE
- Journal :
- Journal of applied physiology (Bethesda, Md. : 1985)
- Publication Type :
- Academic Journal
- Accession number :
- 15640391
- Full Text :
- https://doi.org/10.1152/japplphysiol.00907.2004