A mathematical model for measuring blood flow in skeletal muscle with the microdialysis ethanol technique

1995 ◽  
Vol 79 (2) ◽  
pp. 648-659 ◽  
Author(s):  
F. Wallgren ◽  
G. Amberg ◽  
R. C. Hickner ◽  
U. Ekelund ◽  
L. Jorfeldt ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Muscle Tissue ◽  
Theoretical Calculations ◽  
Microdialysis Probe ◽  
Flow Rates ◽  
Perfusate Flow ◽  
Wide Range ◽  
Theory And Experiments ◽  
Good Agreement

A theoretical analysis of the microdialysis ethanol technique in skeletal muscle is presented, and a model governing the transport of ethanol from the microdialysis probe to the capillaries in the muscle tissue is proposed. The model is derived under the assumption of a steady-state situation, and an analytical solution is found for the outflow-to-inflow ratio of ethanol in the perfusate. Theoretically calculated results are compared with experiments, and for at least one of the two probe types used good agreement is achieved in a wide range of blood flow and perfusate flow rates. The main uncertainty factor in the theoretical calculations is the diffusivity of ethanol in muscle tissue, and the value for best agreement between theory and experiments has been used. Error estimates show that for a constant relative error in the outflow-to-inflow ratio of ethanol in the perfusate, low perfusate flow rates give better predictions of the blood flow.

Measurement of osmotic reflection coefficient for small molecules in cat hindlimbs

1989 ◽  
Vol 256 (1) ◽  
pp. H282-H290 ◽  
Author(s):  
M. B. Wolf ◽  
P. D. Watson
Keyword(s):  
Skeletal Muscle ◽  
Reflection Coefficient ◽  
Small Molecules ◽  
Osmotic Pressure ◽  
Maximum Rate ◽  
Reflection Coefficients ◽  
Flow Rates ◽  
Perfusate Flow ◽  
Arterial Inflow ◽  
Osmotic Reflection Coefficient

Capillary osmotic reflection coefficients (sigma) for NaCl, urea, sucrose, and raffinose were measured in the isolated, perfused cat hindlimb using the osmotic transient technique. sigma were determined from the ratio of the maximum rate of transcapillary absorption [delta Jv(max)] to the increase in the osmotic pressure (25-35 mosmol/kg H2O) in the arterial inflow (delta pi a) produced by adding one of the molecules to an albumin-electrolyte perfusate containing isoproterenol (greater than 10(-7) M). delta Jv (max) was determined from organ weight and delta pi a from perfusate osmolalities. For each molecule, the delta Jv(max)/delta pi a ratio increased monotonically with perfusate flow rates (Q) to Q greater than 100 ml.min-1.100 g-1. This ratio was independent of the size of the delta pi a. Apparent sigma values were calculated by dividing these ratios by the capillary hydraulic capacity determined in other studies. At low Q, apparent sigma was comparable to the approximately 0.1 values found by others in skeletal muscle. At the highest Q, apparent sigma for these molecules were at least 0.5. These data are consistent with at least 50% of transcapillary water flow moving through a water-exclusive pathway.

scholarly journals Microdialysis of skeletal muscle at rest

1999 ◽  
Vol 58 (4) ◽  
pp. 919-923 ◽  
Author(s):  
Jan Henriksson
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Human Skeletal Muscle ◽  
Human Metabolism ◽  
High Expectations ◽  
Perfusate Flow ◽  
Muscle Research ◽  
Interstitial Glucose

Techniques in human skeletal muscle research are by necessity predominantly 'descriptive'.Microdialysis has raised high expectations that it could meet the demand for a method that allows 'mechanistic' investigations to be performed in human skeletal muscle. In the present review, some views are given on how well the initial expectations on the use of the microdialysis technique in skeletal muscle have been fulfilled, and the areas in which additional work is needed in order to validate microdialysis as an important metabolic technique in this tissue. The microdialysis catheter has been equated to an artificial blood vessel, which is introduced into the tissue. By means of this 'vessel' the concentrations of compounds in the interstitial space can be monitored. The concentration of substances in the collected samples is dependent on the rate of perfusate flow. When perfusate flow is slow enough to allow complete equilibration between interstitial and perfusate fluids, the concentration in the perfusate is maximal and identical to the interstitial concentration. Microdialysis data may be influenced by changes in blood flow, especially in instances where the tissue diffusivity limits the recovery in vivo, i.e. when recovery in vitro is 100 %, whereas the recovery in vivo is less than 100 %. Microdialysis data indicate that a significant arterial-interstitial glucose concentration gradient exists in skeletal muscle but not in adipose tissue at rest. While the concentrations of glucose and lactate in the dialysate from skeletal muscle are close to the expected values, the glycerol values obtained for muscle are still puzzling. Ethanol added to the perfusate will be cleared by the tissue at a rate that is determined by the nutritive blood flow (the microdialysis ethanol technique). It is concluded that microdialysis of skeletal muscle has become an important technique for mechanistic studies in human metabolism and nutrition.

scholarly journals Major differences in noradrenaline action on lipolysis and blood flow rates in skeletal muscle and adipose tissue in vivo

Diabetologia ◽  
2005 ◽  
Vol 48 (5) ◽  
pp. 946-953 ◽  
Author(s):  
V. Quisth ◽  
S. Enoksson ◽  
E. Blaak ◽  
E. Hagström-Toft ◽  
P. Arner ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Adipose Tissue ◽  
Flow Rates

A Theory of Blood Flow in Skeletal Muscle

1988 ◽  
Vol 110 (1) ◽  
pp. 20-26 ◽  
Author(s):  
G. W. Schmid-Scho¨nbein
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Flow Curve ◽  
Oscillatory Flow ◽  
Viscoelastic Model ◽  
Low Flow ◽  
Pressure Flow ◽  
Closed Form Solutions ◽  
Wide Range ◽  
Theoretical Results

A theoretical analysis of blood flow in the microcirculation of skeletal muscle is provided. The flow in the microvessels of this organ is quasi steady and has a very low Reynolds number. The blood is non-Newtonian and the blood vessels are distensible with viscoelastic properties. A formulation of the problem is provided using a viscoelastic model for the vessel wall which was recently derived from measurements in the rat spinotrapezius muscle (Skalak and Schmid-Scho¨nbein, 1986b). Closed form solutions are derived for several physiologically important cases, such as perfusion at steady state, transient and oscillatory flows. The results show that resting skeletal muscle has, over a wide range of perfusion pressures an almost linear pressure-flow curve. At low flow it exhibits nonlinearities. Vessel distensibility and the non-Newtonian properties of blood both have a strong influence on the shape of the pressure-flow curve. During oscillatory flow the muscle exhibits hysteresis. The theoretical results are in qualitative agreement with experimental observations.

Experimental Measurements of Ingestion Through Turbine Rim Seals—Part II: Rotationally Induced Ingress

2012 ◽  
Vol 135 (2) ◽  
Author(s):  
Carl M. Sangan ◽  
Oliver J. Pountney ◽  
Kunyuan Zhou ◽  
J. Michael Owen ◽  
Mike Wilson ◽  
...  
Keyword(s):  
Experimental Results ◽  
Radial Clearance ◽  
Rotating Fluid ◽  
Flow Rates ◽  
Hot Gas ◽  
Wide Range ◽  
The Common ◽  
Axial Clearance ◽  
Better Than ◽  
Good Agreement

Part I of this two-part paper presented experimental results for externally-induced (EI) ingress, where the ingestion of hot gas through the rim seal into the wheel-space of a gas turbine is controlled by the circumferential variation of pressure in the external annulus. In Part II, experimental results are presented for rotationally-induced (RI) ingress, where the ingestion is controlled by the pressure generated by the rotating fluid in the wheel-space. Although EI ingress is the common form of ingestion through turbine rim seals, RI ingress or combined ingress (where EI and RI ingress are both significant) is particularly important for double seals, where the pressure asymmetries are attenuated in the annular space between the inner and outer seals. In this paper, the sealing effectiveness was determined from concentration measurements, and the variation of effectiveness with sealing flow rate was compared with theoretical curves for RI ingress obtained from an orifice model. Using a nondimensional sealing parameter Φ0 the data could be collapsed onto a single curve, and the theoretical variation of effectiveness with Φ0 was in very good agreement with the data for a wide range of flow rates and rotational speeds. It was shown that the sealing flow required to prevent RI ingress was much less than that needed for EI ingress, and it was also shown that the effectiveness of a radial-clearance seal is significantly better than that for an axial-clearance seal for both EI and RI ingress.

scholarly journals The role of acetic acid on glucose uptake and blood flow rates in the skeletal muscle in humans with impaired glucose tolerance

2015 ◽  
Vol 69 (6) ◽  
pp. 734-739 ◽  
Author(s):  
P Mitrou ◽  
E Petsiou ◽  
E Papakonstantinou ◽  
E Maratou ◽  
V Lambadiari ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Acetic Acid ◽  
Glucose Tolerance ◽  
Impaired Glucose Tolerance ◽  
Glucose Uptake ◽  
Flow Rates

Validation of miniature ultrasonic transit-time flow probes for measurement of renal blood flow in rats

1995 ◽  
Vol 268 (1) ◽  
pp. F175-F178 ◽  
Author(s):  
W. J. Welch ◽  
X. Deng ◽  
H. Snellen ◽  
C. S. Wilcox
Keyword(s):  
Blood Flow ◽  
Renal Blood Flow ◽  
Transit Time ◽  
Ex Vivo ◽  
High Flow ◽  
Flow Rates ◽  
Time Flow ◽  
Wide Range ◽  
Transit Time Flowmeter

This study validates the accuracy of miniature ultrasonic transit-time flow probes for measuring renal blood flow (RBF) in the rat. Probes for 1-mm and 2-mm vessels were calibrated ex vivo using excised arteries at varying flow rates and hematocrit (Hct). Correlation between measured and true flow rates for the 2-mm probe were identical (r = 1.0) at both normal and subnormal Hct values. Correlation for the 1-mm probe was high (r = 0.994) at normal Hct, but varied at both high flow rates and subnormal Hct values. In vivo correlation of RBF measurements using the 1-mm probe with the clearance and extraction of p-aminohippuric acid showed a high correlation (r = 0.84; n = 72, P < 0.0001) over a wide range of flow rates (0.5-21 ml/min) and Hct (36-74%). Zero flow levels remained steady, averaging -0.2 +/- 0.2 ml/min during occlusion in the living animal and -0.1 +/- 0.3 ml/min after exsanguination. This study shows that the ultrasonic transit-time flowmeter (1-mm and 2-mm probes) is a reasonably accurate and reliable method with which to measure RBF in the anesthetized, acute-instrumented rat.

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