Blood flow distribution in working in situ canine muscle during blood flow reduction

1996 ◽  
Vol 80 (6) ◽  
pp. 1978-1983 ◽  
Author(s):  
S. S. Kurdak ◽  
B. Grassi ◽  
P. D. Wagner ◽  
M. C. Hogan
Keyword(s):  
Blood Flow ◽  
Muscle Blood Flow ◽  
Flow Distribution ◽  
Blood Flow Distribution ◽  
Strong Negative Correlation ◽  
Flow Heterogeneity ◽  
Blood Flow Reduction ◽  
Blood Flow Heterogeneity

The purpose of this study was to determine whether reduction in apparent muscle O2 diffusing capacity (Dmo2) calculated during reduced blood flow conditions in maximally working muscle is a reflection of alterations in blood flow distribution. Isolated dog gastrocnemius muscle (n = 6) was stimulated for 3 min to achieve peak O2 uptake (VO2) at two levels of blood flow (controlled by pump perfusion): control (C) conditions at normal perfusion pressure (blood flow = 111 +/- 10 ml.100 g-1.min-1) and reduced blood flow treatment [ischemia (I); 52 +/- 6 ml.100 g-1.min-1]. In addition, maximal vasodilation was achieved by adenosine (A) infusion (10(-2)M) at both levels of blood flow, so that each muscle was subjected randomly to a total of four conditions (C, CA, I, and IA; each separated by 45 min of rest). Muscle blood flow distribution was measured with 15-microns-diameter colored microspheres. A numerical integration technique was used to calculate Dmo2 for each treatment with use of a model that calculates O2 loss along a capillary on the basis of Fick's law of diffusion. Peak VO2 was reduced significantly (P < 0.01) with ischemia and was unchanged by adenosine infusion at either flow rate (10.6 +/- 0.9, 9.7 +/- 1.0, 6.7 +/- 0.2, and 5.9 +/- 0.8 ml.100 g-1.min-1 for C, CA, I, and IA, respectively). Dmo2 was significantly lower by 30-35% (P < 0.01) when flow was reduced (except for CA vs. I; 0.23 +/- 0.03, 0.20 +/- 0.02, 0.16 +/- 0.01, and 0.13 +/- 0.01 ml.100 g-1.min-1.Torr-1 for C, CA, I, and IA, respectively). As expressed by the coefficient of variation (0.45 +/- 0.04, 0.47 +/- 0.04, 0.55 +/- 0.03, and 0.53 +/- 0.04 for C, CA, I, and IA, respectively), blood flow heterogeneity per se was not significantly different among the four conditions when examined by analysis of variance. However, there was a strong negative correlation (r = 0.89, P < 0.05) between Dmo2 and blood flow heterogeneity among the four conditions, suggesting that blood flow redistribution (likely a result of a decrease in the number of perfused capillaries) becomes an increasingly important factor in the determination of Dmo2 as blood flow is diminished.

scholarly journals Effects of dobutamine on intestinal microvascular blood flow heterogeneity and O2 extraction during septic shock

2017 ◽  
Vol 122 (6) ◽  
pp. 1406-1417 ◽  
Author(s):  
Gustavo A. Ospina-Tascón ◽  
Alberto F. García Marin ◽  
Gabriel J. Echeverri ◽  
William F. Bermudez ◽  
Humberto Madriñán-Navia ◽  
...  
Keyword(s):  
Septic Shock ◽  
Blood Flow ◽  
Flow Distribution ◽  
Capillary Density ◽  
Microvascular Blood Flow ◽  
Fixed Dose ◽  
Blood Flow Distribution ◽  
Dynamic Changes ◽  
Flow Heterogeneity ◽  
Blood Flow Heterogeneity

Derangements of microvascular blood flow distribution might contribute to disturbing O2 extraction by peripheral tissues. We evaluated the dynamic relationships between the mesenteric O2 extraction ratio ([Formula: see text]) and the heterogeneity of microvascular blood flow at the gut and sublingual mucosa during the development and resuscitation of septic shock in a swine model of fecal peritonitis. Jejunal-villi and sublingual microcirculation were evaluated using a portable intravital-microscopy technique. Simultaneously, we obtained arterial, mixed-venous, and mesenteric blood gases, and jejunal-tonometric measurements. During resuscitation, pigs were randomly allocated to a fixed dose of dobutamine (5 µg·kg−1·min−1) or placebo while three sham models with identical monitoring served as controls. At the time of shock, we observed a significant decreased proportion of perfused intestinal-villi (villi-PPV) and sublingual percentage of perfused small vessels (SL-PPV), paralleling an increase in [Formula: see text] in both dobutamine and placebo groups. After starting resuscitation, villi-PPV and SL-PPV significantly increased in the dobutamine group with subsequent improvement of functional capillary density, whereas [Formula: see text] exhibited a corresponding significant decrease (repeated-measures ANOVA, P = 0.02 and P = 0.04 for time × group interactions and intergroup differences for villi-PPV and [Formula: see text], respectively). Variations in villi-PPV were paralleled by variations in [Formula: see text] ( R2 = 0.88, P < 0.001) and these, in turn, by mesenteric lactate changes ( R2 = 0.86, P < 0.001). There were no significant differences in cardiac output and systemic O2 delivery throughout the experiment. In conclusion, dynamic changes in microvascular blood flow heterogeneity at jejunal mucosa are closely related to the mesenteric O2 extraction ratio, suggesting a crucial role for microvascular blood flow distribution on O2 uptake during development and resuscitation from septic shock. NEW & NOTEWORTHY Our observations suggest that dynamic changes in the heterogeneity of microvascular blood flow at the gut mucosa are closely related to mesenteric O2 extraction, thus supporting the role of decreasing functional capillary density and increased intercapillary distances on alterations of O2 uptake during development and resuscitation from septic shock. Addition of a low-fixed dose of dobutamine might reverse such flow heterogeneity, improving microcirculatory flow distribution and tissue O2 consumption.

scholarly journals Comparison of exogenous adenosine and voluntary exercise on human skeletal muscle perfusion and perfusion heterogeneity

2010 ◽  
Vol 108 (2) ◽  
pp. 378-386 ◽  
Author(s):  
Ilkka Heinonen ◽  
Jukka Kemppainen ◽  
Kimmo Kaskinoro ◽  
Juha E. Peltonen ◽  
Ronald Borra ◽  
...  
Keyword(s):  
Blood Flow ◽  
High Intensity ◽  
Muscle Blood Flow ◽  
Flow Distribution ◽  
Voluntary Exercise ◽  
Adenosine Infusion ◽  
Blood Flow Distribution ◽  
Flow Heterogeneity ◽  
Exercise Hyperemia ◽  
Exercise Induced

Adenosine is a widely used pharmacological agent to induce a “high-flow” control condition to study the mechanisms of exercise hyperemia, but it is not known how well an adenosine infusion depicts exercise-induced hyperemia, especially in terms of blood flow distribution at the capillary level in human muscle. Additionally, it remains to be determined what proportion of the adenosine-induced flow elevation is specifically directed to muscle only. In the present study, we measured thigh muscle capillary nutritive blood flow in nine healthy young men using PET at rest and during the femoral artery infusion of adenosine (1 mgmin−1l thigh volume−1), which has previously been shown to induce a maximal whole thigh blood flow of ∼8 l/min. This response was compared with the blood flow induced by moderate- to high-intensity one-leg dynamic knee extension exercise. Adenosine increased muscle blood flow on average to 40 ± 7 ml·min−1·100 g muscle−1 with an aggregate value of 2.3 ± 0.6 l/min for the whole thigh musculature. Adenosine also induced a substantial change in blood flow distribution within individuals. Muscle blood flow during the adenosine infusion was comparable with blood flow in moderate- to high-intensity exercise (36 ± 9 ml·min−1·100 g muscle−1), but flow heterogeneity was significantly higher during the adenosine infusion than during voluntary exercise. In conclusion, a substantial part of the flow increase in the whole limb blood flow induced by a high-dose adenosine infusion is conducted through the physiological non-nutritive shunt in muscle and/or also through tissues of the limb other than muscle. Additionally, an intra-arterial adenosine infusion does not mimic exercise hyperemia, especially in terms of muscle capillary flow heterogeneity, while the often-observed exercise-induced changes in capillary blood flow heterogeneity likely reflect true changes in nutritive flow linked to muscle fiber and vascular unit recruitment.

Effect of [Hb] on blood flow distribution and O2 transport in maximally working skeletal muscle

1995 ◽  
Vol 79 (5) ◽  
pp. 1729-1735 ◽  
Author(s):  
S. S. Kurdak ◽  
B. Grassi ◽  
P. D. Wagner ◽  
M. C. Hogan
Keyword(s):  
Blood Flow ◽  
Muscle Blood Flow ◽  
Flow Distribution ◽  
Hemoglobin Concentration ◽  
Related Factor ◽  
Blood Flow Distribution ◽  
O2 Uptake ◽  
Cell Spacing ◽  
O2 Delivery

We investigated whether the reduction in calculated muscle diffusion capacity for O2 (DmO2) previously shown to occur with lowered hemoglobin concentration ([Hb]) perfusion of maximally working muscle is related to changes in the blood flow distribution. If blood flow distribution is altered during low [Hb] conditions, the reduction in the calculated DmO2 may in fact be due to increasing heterogeneity and not to some other hemoglobin-related factor. Color-stained (15-microns-diam) microspheres were injected into the artery supplying maximally working isolated in situ dog gastrocnemius muscle (n = 6) while it was being perfused (flow controlled by pump perfusion) with whole blood at three different levels of [Hb] (14.1 +/- 0.5, 8.9 +/- 0.4, and 5.7 +/- 0.4 (SE) g/100 ml] in a blocked-order design. Muscle blood flow and arterial PO2 were not changed as [Hb] was altered. Maximal O2 uptake (11.8 +/- 1.3, 8.2 +/- 0.8, and 6.0 +/- 0.9 ml.100 g-1 min-1 for those [Hb] values, respectively) and the associated estimate of DmO2 (0.25 +/- 0.03, 0.18 +/- 0.03, and 0.15 +/- 0.03 ml.100 g-1.min-1.Torr-1) declined significantly (P < 0.05) with [Hb]. However, the dispersion of the blood flow distribution did not change significantly and, if anything, indicated less heterogeneity at lower [Hb] (coefficient of variation - 0.52 +/- 0.06, 0.46 +/- 0.05, and 0.43 +/- 0.03). These results suggest that in maximally working canine muscle in situ, when O2 delivery is reduced by lowering [Hb] (at constant blood flow), changes in blood flow distribution play no significant role in the reduction of maximal O2 uptake and calculated DmO2. The apparent increase in the resistance to O2 diffusion (i.e., reduction in the DmO2) during anemia may therefore be a result of increased red blood cell spacing in the capillary, slow chemical off-loading kinetics of O2 from Hb, or some other effect that remains to be determined.

Influence of simulated microgravity on cardiac output and blood flow distribution during exercise

1995 ◽  
Vol 79 (5) ◽  
pp. 1762-1768 ◽  
Author(s):  
C. R. Woodman ◽  
L. A. Sebastian ◽  
C. M. Tipton
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Aerobic Capacity ◽  
Muscle Blood Flow ◽  
Knee Extensor ◽  
Flow Distribution ◽  
Blood Flow Distribution ◽  
Heavy Exercise ◽  
Cage Control ◽  
Impaired Ability

Rats exposed to simulated conditions of microgravity by head-down suspension (HDS) exhibit reductions in aerobic capacity. This may be due to an impaired ability to augment cardiac output and to redistribute blood flow during exercise. The purpose of this investigation was to measure cardiac output and blood flow distribution in rats that were exposed to 14 days of HDS or cage control conditions. Measurements were obtained at rest and during light-intensity (15 m/min) and heavy-intensity (25 m/min; 10% grade) treadmill exercise. Cardiac output was similar in HDS and cage control rats at rest and light exercise but was significantly lower in HDS rats (-33%) during heavy exercise. Soleus muscle blood flow (ml/min) was lower at rest and during exercise in HDS rats; however, when expressed relative to muscle mass (ml.min-1.100 g-1), soleus blood flow was lower only during light exercise. Plantaris muscle blood flow was lower in HDS rats during heavy exercise. Blood flow to the ankle flexor, knee extensor, and knee flexor muscles was not altered by HDS. Blood flow to the spleen and kidney was significantly higher in HDS rats. It was concluded that the reduction in aerobic capacity associated with HDS is due in part to an impaired ability to augment cardiac output during exercise.

scholarly journals Measurement of pulmonary blood flow by fractal analysis of flow heterogeneity in isolated canine lungs

1996 ◽  
Vol 81 (5) ◽  
pp. 2039-2045 ◽  
Author(s):  
Scott A. Barman ◽  
Laryssa L. McCloud ◽  
John D. Catravas ◽  
Ina C. Ehrhart
Keyword(s):  
Blood Flow ◽  
Fractal Dimension ◽  
Fractal Analysis ◽  
Pulmonary Blood Flow ◽  
Flow Distribution ◽  
Blood Flow Rate ◽  
Blood Flow Distribution ◽  
Flow Rates ◽  
Flow Heterogeneity ◽  
Lung Lobes

Barman, Scott A., Laryssa L. McCloud, John D. Catravas, and Ina C. Ehrhart. Measurement of pulmonary blood flow by fractal analysis of flow heterogeneity in isolated canine lungs. J. Appl. Physiol. 81(5): 2039–2045, 1996.—Regional heterogeneity of lung blood flow can be measured by analyzing the relative dispersion (RD) of mass (weight)-flow data. Numerous studies have shown that pulmonary blood flow is fractal in nature, a phenomenon that can be characterized by the fractal dimension and the RD for the smallest realizable volume element (piece size). Although information exists for the applicability of fractal analysis to pulmonary blood flow in whole animal models, little is known in isolated organs. Therefore, the present study was done to determine the effect of blood flow rate on the distribution of pulmonary blood flow in the isolated blood-perfused canine lung lobe by using fractal analysis. Four different radiolabeled microspheres (141Ce,95Nb,85Sr, and51Cr), each 15 μm in diameter, were injected into the pulmonary lobar artery of isolated canine lung lobes ( n = 5) perfused at four different flow rates ( flow 1 = 0.42 ± 0.02 l/min; flow 2 = 1.12 ± 0.07 l/min; flow 3 = 2.25 ± 0.17 l/min; flow 4 = 2.59 ± 0.17 l/min), and the pulmonary blood flow distribution was measured. The results of the present study indicate that under isogravimetric blood flow conditions, all regions of horizontally perfused isolated lung lobes received blood flow that was preferentially distributed to the most distal caudal regions of the lobe. Regional pulmonary blood flow in the isolated perfused canine lobe was heterogeneous and fractal in nature, as measured by the RD. As flow rates increased, fractal dimension values (averaging 1.22 ± 0.08) remained constant, whereas RD decreased, reflecting more homogeneous blood flow distribution. At any given blood flow rate, high-flow areas of the lobe received a proportionally larger amount of regional flow, suggesting that the degree of pulmonary vascular recruitment may also be spatially related.

scholarly journals Critical speed in the rat: implications for hindlimb muscle blood flow distribution and fibre recruitment

2010 ◽  
Vol 588 (24) ◽  
pp. 5077-5087 ◽  
Author(s):  
Steven W. Copp ◽  
Daniel M. Hirai ◽  
Timothy I. Musch ◽  
David C. Poole
Keyword(s):  
Blood Flow ◽  
Critical Speed ◽  
Muscle Blood Flow ◽  
Flow Distribution ◽  
Blood Flow Distribution ◽  
Hindlimb Muscle

scholarly journals Cardiac Output and Regional Blood Flow in Gills and Muscles after Exhaustive Exercise in Rainbow Trout (Salmo Gairdneri)

1983 ◽  
Vol 105 (1) ◽  
pp. 1-14
Author(s):  
PETER NEUMANN ◽  
GEORGE F. HOLETON ◽  
NORBERT HEISLER
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Rainbow Trout ◽  
Muscle Blood Flow ◽  
Recovery Period ◽  
Flow Distribution ◽  
Strenuous Exercise ◽  
Salmo Gairdneri ◽  
Diffusion Resistance ◽  
Blood Flow Distribution

Rainbow trout (Salmo gairdneri) were electrically stimulated to exhausting activity and the changes in cardiac output and blood flow distribution to gills and systemic tissues resulting from the developing severe lactacidosis were repeatedly measured by the microsphere method (15 μm). Determination of cardiac output by application of the Fick principle resulted in values not significantly different from cardiac output measured by the indicator dilution technique, suggesting that cutaneous respiration, oxygen consumption, and arterio-venous shunting were insignificant under these conditions. Following muscular activity, cardiac output was elevated by up to 60%. In the gills, the blood flow distribution in the gill arches showed a consistent pattern, even during lactacidosis, with a higher perfusion in gill arches II and III, and in the middle sections of individual gills. Blood flow to white and red muscle was increased much more than cardiac output (+230 and +490%, respectively) such that blood flow to other tissues was actually reduced. We conclude that the elimination of lactate from muscle cells during the recovery period from strenuous exercise is delayed, not as a result of an impaired post-exercise muscle blood flow, but probably as a result of a high diffusion resistance in the cell membrane. Note: Deceased.

Vasoconstrictor role for vasopressin in conscious, sodium-depleted rats

1987 ◽  
Vol 253 (4) ◽  
pp. H763-H769
Author(s):  
B. Jover ◽  
M. Dupont ◽  
A. Mimran ◽  
R. Woods ◽  
B. McGrath
Keyword(s):  
Blood Flow ◽  
Regional Blood Flow ◽  
Muscle Blood Flow ◽  
Flow Distribution ◽  
Renin Angiotensin System ◽  
Adrenergic System ◽  
Blood Flow Distribution ◽  
Sprague Dawley ◽  
Vascular Bed ◽  
Renal Vascular

To define the role of vasopressin as a vasoconstrictor hormone in sodium depletion, systemic hemodynamics and regional blood flow distribution were examined in conscious Sprague-Dawley rats after 6 days of a low-sodium diet. Studies were performed after selective or combined blockade with the vasopressin antagonist [d(CH2)5Tyr(Me)]AVP (AVPA), enalaprilat (CEI), and phentolamine (PHENTOL). Plasma levels of vasopressin were increased significantly after CEI and increased further after PHENTOL and CEI plus PHENTOL. AVPA had no effect on blood pressure, whether given alone or in the presence of PHENTOL, CEI, or CEI plus PHENTOL. Significant falls in peripheral vascular resistance associated with reflex increases in cardiac output were observed when AVPA was given to animals pretreated with either CEI or PHENTOL but not both. AVPA alone produced no significant changes in regional blood flow distribution, but a vasoconstrictor action of vasopressin in the renal vascular bed was revealed after prior treatment with CEI or PHENTOL. Muscle blood flow was also increased in the PHENTOL plus AVPA group compared with the PHENTOL group. No significant additional effects of AVPA were revealed by pretreatment with CEI, PHENTOL, or CEI plus PHENTOL for mesenteric, hepatic, splenic, or cerebral vascular beds. It is suggested that vasopressin acts as a vasoconstrictor hormone in conscious sodium-depleted rats when either the renin-angiotensin system or alpha-adrenergic system is inhibited but not when both systems are blocked. The renal vascular bed is an important site for vasopressin-induced vasoconstriction under these circumstances.

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