Parametric Analysis of the Relationship between End-capillary and Mean Tissue PO2as Predicted by a Mathematical Model

Sharan, Maithili; Gupta, Suman; Popel, Aleksander S.

doi:10.1006/jtbi.1998.0805

Cited by 12 publications

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“…The venous and tissue PO 2 are reduced with an increase in consumption rate. The tissue PO 2 is lower than the venous PO 2 when the consumption rate is elevated by 50% from the control whereas it becomes higher than the venous PO 2 when the metabolic rate is reduced by 50% for both values of P 50p : The prediction of tissue PO 2 lower/ higher than the venous PO 2 is consistent with the earlier studies (Ye et al, 1993(Ye et al, , 1994Sharan et al, 1998b).…”

Section: Model For Oxygen Transport In Brainsupporting

confidence: 88%

“…The difference between the tissue and venous PO 2 decreases as P 50p is increased from 2 to 30 mmHg and it increases when P 50p rises from 30 to 50 mmHg. The relationship between the tissue PO 2 and the venous PO 2 is consistent with our earlier study (Sharan et al, 1998b) on the relationship between end-capillary and mean tissue PO 2 .…”

supporting

confidence: 89%

“…Eliminating J from eqn (C.11) and (C.14) and taking the average in the capillary region, we get Sharan et al (1998b). In the earlier model (Sharan et al, 1998a) …”

Section: Appendix a Derivation Of Equations For O 2 Transport In A MImentioning

confidence: 97%

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A Compartmental Model for Oxygen Transport in Brain Microcirculation in the Presence of Blood Substitutes

Sharan

Popel

2002

Journal of Theoretical Biology

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Section: Model For Oxygen Transport In Brainsupporting

confidence: 88%

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confidence: 89%

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A Compartmental Model for Oxygen Transport in Brain Microcirculation in the Presence of Blood Substitutes

Sharan

Popel

2002

Journal of Theoretical Biology

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“…Although the two tensions have been shown in previous studies (7,11) to be closely correlated in some in vivo models, the gradient has been shown in mathematical models to potentially vary to some degree and in either direction as other parameters are varied over their physiological range (11,33,34). This poses an inherent constraint for in vivo studies examining mucosal tissue V O 2 and necessitated equating mucosal venous PO 2 with mucosal tissue PO 2 in our experiments.…”

Section: Discussionmentioning

confidence: 86%

Dopamine-1 receptor stimulation impairs intestinal oxygen utilization during critical hypoperfusion

Guzmán

Rosado

Kruse

2003

American Journal of Physiology-Heart and Circulatory Physiology

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. Dopamine-1 receptor stimulation impairs intestinal oxygen utilization during critical hypoperfusion. Am J Physiol Heart Circ Physiol 284: H668-H675, 2003; 10.1152/ ajpheart.00636.2002.-Effects of a dopamine-1 (DA-1) receptor agonist on systemic and intestinal oxygen delivery (Ḋ O2)-uptake relationships were studied in anesthetized dogs during sequential hemorrhage. Control (group 1) and experimental animals (group 2) were treated similarly except for the addition of fenoldopam (1.0 g ⅐ kg Ϫ1 ⅐ min Ϫ1 ) in group 2. Both groups had comparable systemic critical Ḋ O2 (Ḋ O2crit), but animals in group 2 had a higher gut Ḋ O2crit (1.12 Ϯ 1.13 vs. 0.80 Ϯ 0.09 ml ⅐ kg Ϫ1 ⅐ min Ϫ1 , P Ͻ 0.05). At the mucosal level, a clear biphasic delivery-uptake relationship was not observed in group 1; thus oxygen consumption by the mucosa may be supply dependent under physiological conditions. Group 2 demonstrated higher peak mucosal blood flow and lack of supply dependency at higher mucosal Ḋ O2 levels. Fenoldopam resulted in a more conspicuous biphasic relationship at the mucosa and a rightward shift of overall splanchnic Ḋ O2crit despite increased splanchnic blood flow. These findings suggest that DA-1 receptor stimulation results in increased gut perfusion heterogeneity and maldistribution of perfusion, resulting in increased susceptibility to ischemia. oxygen supply dependency; splanchnic ischemia; vasodilators AT A GIVEN LEVEL OF METABOLIC demand, systemic oxygen consumption is maintained constant despite moderate changes in systemic oxygen delivery (Ḋ O 2 ) (6,14,25,30,31). This is accomplished by changes in peripheral oxygen extraction, with a consequent decrease in mixed venous oxygen content. However, once Ḋ O 2 falls below a critical threshold, parallel decreases in oxygen uptake (V O 2 ) are observed. This "oxygen supply dependency" is accompanied by maximal tissue oxygen extraction, development of anaerobic metabolism, and venous hypercarbia (12,14).The splanchnic circulation is particularly susceptible to ischemia during shock (1, 17). This regional ischemia is thought to play an important role in the development of multiple-system organ failure by activation of a systemic inflammatory response (22,35). In an effort to prevent or decrease gut ischemia, numerous gut-directed therapeutic approaches have been attempted with conflicting results (12). To date, clinical attempts to improve gut perfusion have focused mainly on the use of vasoactive drugs (16,20,21). However, the lack of splanchnic selectivity by these vasoactive agents could yield unwanted effects on gut oxygenation and desired outcomes. The most "gut-selective" vasoactive agent in common clinical use is dopamine given at relatively low doses. In animal models, low-dose dopamine infusions accelerate the onset of gut ischemia, impair gut oxygen extraction, and decrease gut V O 2 (9, 32). It is unclear from these data whether the adverse effects of low-dose dopamine are secondary to redistribution of flow within the gut or due to dopamine-induced alterations i...

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“…The full potential of our model in terms of transport and tissue mechanics (Baish et al, 1997;Dutta and Popel, 1994;Helmlinger et al, 1997a,b;Hobbs et al, 1998;Kim et al, 1990;Sharan et al, 1998), tumor angiogenesis (Carmeliet and Jain, 2000), and more fundamental questions like scaling relations or the debatable role of "fractal geometry" for the design of vascular systems (see http://discuss. santafe.edu/biofractals) remains to be evaluated.…”

Section: Resultsmentioning

confidence: 99%

Structural and biophysical simulation of angiogenesis and vascular remodeling

Gödde

Kurz

2001

Developmental Dynamics

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The purpose of this report is to introduce a new computer model for the simulation of microvascular growth and remodeling into arteries and veins that imitates angiogenesis and blood flow in real vascular plexuses. A C؉؉ computer program was developed based on geometric and biophysical initial and boundary conditions. Geometry was defined on a two-dimensional isometric grid by using defined sources and drains and elementary bifurcations that were able to proliferate or to regress under the influence of random and deterministic processes. Biophysics was defined by pressure, flow, and velocity distributions in the network by using the nodal-admittance-matrix-method, and accounting for hemodynamic peculiarities like Fahraeus-Lindqvist effect and exchange with extravascular tissue. The proposed model is the first to simulate interdigitation between the terminal branches of arterial and venous trees. This was achieved by inclusion of vessel regression and anastomosis in the capillary plexus and by remodeling in dependence from hemodynamics. The choice of regulatory properties influences the resulting vascular patterns. The model predicts interdigitating arteriovenous patterning if shear stress-dependent but not pressure-dependent remodeling was applied. By approximating the variability of natural vascular patterns, we hope to better understand homogeneity of transport, spatial distribution of hemodynamic properties and biomass allocation to the vascular wall or blood during development, or during evolution of circulatory systems.

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Parametric Analysis of the Relationship between End-capillary and Mean Tissue PO2as Predicted by a Mathematical Model

Cited by 12 publications

References 0 publications

A Compartmental Model for Oxygen Transport in Brain Microcirculation in the Presence of Blood Substitutes

A Compartmental Model for Oxygen Transport in Brain Microcirculation in the Presence of Blood Substitutes

Dopamine-1 receptor stimulation impairs intestinal oxygen utilization during critical hypoperfusion

Structural and biophysical simulation of angiogenesis and vascular remodeling

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