V̇o2 on-kinetics in isolated canine muscle in situ during slowed convective O2 delivery

2012 ◽  
Vol 112 (1) ◽  
pp. 9-19 ◽  
Author(s):  
Matthew L. Goodwin ◽  
Andrés Hernández ◽  
Nicola Lai ◽  
Marco E. Cabrera ◽  
L. Bruce Gladden
Keyword(s):  
Blood Flow ◽  
Steady State ◽  
Near Infrared ◽  
Transition Period ◽  
Blood Flows ◽  
Mean Response Time ◽  
Experimental Trial ◽  
Muscle Complex ◽  
Anesthetized Dogs

The purpose of this study was to examine O2 uptake (V̇o2) on-kinetics when the spontaneous blood flow (and therefore O2 delivery) on-response was slowed by 25 and 50 s. The isolated gastrocnemius muscle complex (GS) in situ was studied in six anesthetized dogs during transitions from rest to a submaximal metabolic rate (≈50–70% of peak V̇o2). Four trials were performed: 1) a pretrial in which resting and steady-state blood flows were established, 2) a control trial in which the blood flow on-kinetics mean response time (MRT) was set at 20 s (CT20), 3) an experimental trial in which the blood flow on-kinetics MRT was set at 45 s (EX45), and 4) an experimental trial in which the blood flow on-kinetics MRT was set at 70 s (EX70). Slowing O2 delivery via slowing blood flow on-kinetics resulted in a linear slowing of the V̇o2 on-kinetics response ( R = 0.96). Average MRT values for CT20, EX45, and EX70 V̇o2 on-kinetics were (means ± SD) 17 ± 2, 23 ± 4, and 26 ± 3 s, respectively ( P < 0.05 among all). During these transitions, slowing blood flow resulted in greater muscle deoxygenation (as indicated by near-infrared spectroscopy), suggesting that lower intracellular Po2 values were reached. In this oxidative muscle, V̇o2 and O2 delivery were closely matched during the transition period from rest to steady-state contractions. In conjunction with our previous work showing that speeding O2 delivery did not alter V̇o2 on-kinetics under similar conditions, it appears that spontaneously perfused skeletal muscle operates at the nexus of sufficient and insufficient O2 delivery in the transition from rest to contractions.

Contraction-by-contraction V̇o2 and computer-controlled pump perfusion as novel techniques to study skeletal muscle metabolism in situ

2010 ◽  
Vol 108 (3) ◽  
pp. 705-712 ◽  
Author(s):  
Andrés Hernández ◽  
Matthew L. Goodwin ◽  
Nicola Lai ◽  
Marco E. Cabrera ◽  
James R. McDonald ◽  
...  
Keyword(s):  
Blood Flow ◽  
Moving Average ◽  
Computer Software ◽  
Muscle Metabolism ◽  
New Techniques ◽  
Muscle Oxygen ◽  
Flow Adjustment ◽  
Train Duration ◽  
Muscle Complex

The purpose of this research was to develop new techniques to 1) rapidly sample venous O2 saturation to determine contraction-by-contraction oxygen uptake (V̇o2), and 2) precisely control the rate and pattern of blood flow adjustment from one chosen steady state to another. An indwelling inline oximeter probe connected to an Oximetrix 3 meter was used to sample venous oxygen concentration ([O2]) (via fractional saturation of Hb with O2). Data from the Oximetrix 3 were filtered, deconvolved, and processed by a moving average second by second. Computer software and a program written in-house were used to control blood flow with a peristaltic pump. The isolated canine gastrocnemius muscle complex (GS) in situ was utilized to test these techniques. A step change in metabolic rate was elicited by stimulating GS muscles via their sciatic nerves (supramaximal voltage, 8 V; 50 Hz, 0.2-ms pulse width; train duration 200 ms) at a rate of either 1 contraction/2 s, or 2 contractions/3 s. With arterial [O2] maintained constant, blood flow and calculated venous [O2] were averaged over each contraction cycle and used in the Fick equation to calculate contraction-by-contraction V̇o2. About 5–8 times more data points were obtained with this method compared with traditional manual sampling. Software-controlled pump perfusion enabled the ability to mimic spontaneous blood flow on-kinetics (τ: 14.3 s) as well as dramatically speed (τ: 2.0 s) and slow (τ: 63.3 s) on-kinetics. These new techniques significantly improve on existing methods for mechanistically altering blood flow kinetics as well as accurately measuring muscle oxygen consumption kinetics during transitions between metabolic rates.

Contribution of bile to postprandial intestinal hyperemia

1980 ◽  
Vol 238 (4) ◽  
pp. G284-G288 ◽  
Author(s):  
P. R. Kvietys ◽  
R. H. Gallavan ◽  
C. C. Chou
Keyword(s):  
Amino Acids ◽  
Blood Flow ◽  
Oleic Acid ◽  
Caproic Acid ◽  
Local Blood Flow ◽  
Vascular Effects ◽  
Bile Concentration ◽  
Anesthetized Dogs ◽  
Per Se

The role played by bile in postprandial intestinal hyperemia was examined by comparing the vascular effects of luminal placement of various nutrients with and without bile in situ jejunal segments of anesthetized dogs. The bile concentration was either 10 or 33% of that in the gallbladder. At these concentrations, bile per se in the jejunal lumen does not alter local blood flow. In the absence of bile, only glucose increased flow (+5% above control). With 10% bile, glucose and oleic acid increased flow by 10 and 24%, whereas with 33% bile, glucose, oleic acid, caproic acid, and amino acids increased flow by 22, 21, 12, and 12% above control, respectively. Triolein increased flow only after digestion by pancreatic enzymes and mixing with bile. Dipeptides did not alter flow with or without bile. Thus, bile plays an important role in postprandial intestinal hyperemia because it potentiates the glucose-induced hyperemia and because only in its presence can oleic acid, amino acids, caproic acid, and digested triolein increase intestinal blood flow.

scholarly journals Role of convective O2 delivery in determiningV˙o 2 on-kinetics in canine muscle contracting at peak V˙o 2

2000 ◽  
Vol 89 (4) ◽  
pp. 1293-1301 ◽  
Author(s):  
Bruno Grassi ◽  
Michael C. Hogan ◽  
Kevin M. Kelley ◽  
William G. Aschenbach ◽  
Jason J. Hamann ◽  
...  
Keyword(s):  
Blood Flow ◽  
Steady State ◽  
Muscle Fatigue ◽  
Oxidative Metabolism ◽  
Muscle Blood Flow ◽  
Content Difference ◽  
O2 Delivery ◽  
Gastrocnemius Muscles

A previous study (Grassi B, Gladden LB, Samaja M, Stary CM, and Hogan MC, J Appl Physiol 85: 1394–1403, 1998) showed that convective O2 delivery to muscle did not limit O2 uptake (V˙o 2) on-kinetics during transitions from rest to contractions at ∼60% of peakV˙o 2. The present study aimed to determine whether this finding is also true for transitions involving contractions of higher metabolic intensities.V˙o 2 on-kinetics were determined in isolated canine gastrocnemius muscles in situ ( n = 5) during transitions from rest to 4 min of electrically stimulated isometric tetanic contractions corresponding to the muscle peakV˙o 2. Two conditions were compared: 1) spontaneous adjustment of muscle blood flow (Q˙) (Control) and 2) pump-perfused Q˙, adjusted ∼15–30 s before contractions at a constant level corresponding to the steady-state value during contractions in Control (Fast O2 Delivery). In Fast O2 Delivery, adenosine was infused intra-arterially. Q˙ was measured continuously in the popliteal vein; arterial and popliteal venous O2 contents were measured at rest and at 5- to 7-s intervals during the transition. Muscle V˙o 2 was determined as Q˙times the arteriovenous blood O2 content difference. The time to reach 63% of the V˙o 2 difference between resting baseline and steady-state values during contractions was 24.9 ± 1.6 (SE) s in Control and 18.5 ± 1.8 s in Fast O2 Delivery ( P < 0.05). FasterV˙o 2 on-kinetics in Fast O2Delivery was associated with an ∼30% reduction in the calculated O2 deficit and with less muscle fatigue. During transitions involving contractions at peak V˙o 2, convective O2 delivery to muscle, together with an inertia of oxidative metabolism, contributes in determining theV˙o 2 on-kinetics.

Influence of training on blood flow to different skeletal muscle fiber types

1983 ◽  
Vol 55 (4) ◽  
pp. 1072-1078 ◽  
Author(s):  
B. G. Mackie ◽  
R. L. Terjung
Keyword(s):  
Blood Flow ◽  
Muscle Fiber Types ◽  
Fiber Types ◽  
Plantaris Muscle ◽  
Blood Flows ◽  
Energy Demands ◽  
Flow Capacity ◽  
Slow Twitch ◽  
Fast Twitch

Blood flows to fast-twitch red (FTR), fast-twitch white (FTW), and slow-twitch red (STR) fiber sections of the gastrocnemius-soleus-plantaris muscle group of sedentary and trained rats were determined using radiolabeled microspheres during the 1st and 10th min of in situ contractions at frequencies ranging from 7.5 to 90 tetani/min. Treadmill training increased the cytochrome c content of both FTW (6.0 +/- 0.13 nmol/g to 12.2 +/- 0.27) and FTR (22.2 +/- 0.32 to 26.7 +/- 0.25) muscle. Loss of tension, evident at 15 tetani/min and above, was less (P less than 0.001) in trained animals. Although steady-state blood flows (10th min) to FTR and STR fibers were not altered by training, initial flows (1st min) to the trained FTR section were greater (P less than 0.025). Overall initial flows to both red fiber types were excessively high at the easier contraction conditions, but subsequently declined to values more reflective of the expected energy demands. This time-dependent relative hyperemia was not found in either sedentary or trained FTW muscle. However, training increased the maximal blood flow in the FTW sections [60 +/- 3.2 (n = 36) vs. 88 +/- 5.2 ml X min X 100 g-1 (n = 36)]. This 40-50% increase in FTW blood flow would produce only a modest 10% increase in blood flow to a whole mixed-fiber muscle, since the flow capacity of the FTW muscle is only one third to one fourth that of FTR muscle. This overall increase in blood flow, however, is similar to changes in VO2max found in trained rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Transient response of glomerular filtration rate and renal blood flow to step changes in arterial pressure

1977 ◽  
Vol 233 (5) ◽  
pp. F396-F402 ◽  
Author(s):  
T. E. Jackson ◽  
A. C. Guyton ◽  
J. E. Hall
Keyword(s):  
Blood Flow ◽  
Glomerular Filtration Rate ◽  
Steady State ◽  
Arterial Pressure ◽  
Glomerular Filtration ◽  
Renal Blood Flow ◽  
Filtration Rate ◽  
Hemodynamic Changes ◽  
Proximal Tubular ◽  
Anesthetized Dogs

Measurement of rapid renal hemodynamic changes were made for 90 s in pentobarbital-anesthetized dogs following step increases and decreases in renal arterial pressure between 80 and 120 mm Hg. Transient analysis was used to observe time characteristics of the autoregulatory relationships which are obscured in steadystate measurements. Temporal decoupling of blood flow and glomerular filtration rate (GFR) occurred with both step increases and decreases of arterial pressure. Steady-state autoregulation of blood flow was attained in about 30 s, whereas steady-state autoregulation of GFR was not demonstrably attained even 90 s after the arterial pressure maneuver. The temporal decoupling of renal blood flow and GRR supports the concept of transient involvement of proximal tubular dynamics and efferent resistance changes during acute autoregulation of GFR following step changes in arterial pressure.

scholarly journals Faster adjustment of O2delivery does not affect V˙o 2 on-kinetics in isolated in situ canine muscle

1998 ◽  
Vol 85 (4) ◽  
pp. 1394-1403 ◽  
Author(s):  
Bruno Grassi ◽  
L. Bruce Gladden ◽  
Michele Samaja ◽  
Creed M. Stary ◽  
Michael C. Hogan
Keyword(s):  
Blood Flow ◽  
Steady State ◽  
Experimental Model ◽  
Oxidative Metabolism ◽  
Constant Level ◽  
Model Elimination ◽  
Content Difference ◽  
The Difference ◽  
Gastrocnemius Muscles

The mechanism(s) limiting muscle O2 uptake (V˙o 2) kinetics was investigated in isolated canine gastrocnemius muscles ( n = 7) during transitions from rest to 3 min of electrically stimulated isometric tetanic contractions (200-ms trains, 50 Hz; 1 contraction/2 s; 60–70% of peakV˙o 2). Two conditions were mainly compared: 1) spontaneous adjustment of blood flow (Q˙) [control, spontaneousQ˙ (C Spont)]; and 2) pump-perfusedQ˙, adjusted ∼15 s before contractions at a constant level corresponding to the steady-state value during contractions in C Spont [faster adjustment of O2 delivery (Fast O2 Delivery)]. During Fast O2 Delivery, 1–2 ml/min of 10−2 M adenosine were infused intra-arterially to prevent inordinate pressure increases with the elevated Q˙. The purpose of the study was to determine whether a faster adjustment of O2 delivery would affectV˙o 2 kinetics.Q˙ was measured continuously; arterial ([Formula: see text]) and popliteal venous ([Formula: see text]) O2 contents were determined at rest and at 5- to 7-s intervals during contractions; O2 delivery was calculated asQ˙ ⋅ [Formula: see text], and V˙o 2 was calculated asQ˙ ⋅ arteriovenous O2 content difference. Times to reach 63% of the difference between baseline and steady-stateV˙o 2 during contractions were 23.8 ± 2.0 (SE) s in C Spont and 21.8 ± 0.9 s in Fast O2 Delivery (not significant). In the present experimental model, elimination of any delay in O2 delivery during the rest-to-contraction transition did not affect muscleV˙o 2 kinetics, which suggests that this kinetics was mainly set by an intrinsic inertia of oxidative metabolism.

Pulmonary and systemic blood flow contributions to upper airways in canine lung

1988 ◽  
Vol 255 (5) ◽  
pp. H1130-H1135 ◽  
Author(s):  
S. A. Barman ◽  
J. L. Ardell ◽  
J. C. Parker ◽  
M. L. Perry ◽  
A. E. Taylor
Keyword(s):  
Blood Flow ◽  
Primary Source ◽  
Upper Airways ◽  
Systemic Blood Flow ◽  
Tracheal Cartilage ◽  
Blood Flows ◽  
Drainage Patterns ◽  
Isolated Lung ◽  
Anesthetized Dogs ◽  
The Right

The blood flow contributions and drainage patterns of the pulmonary and systemic circulations in the upper airways (trachea and main bronchi) were assessed in anesthetized dogs by injecting 15-micron radiolabeled microspheres into the right and left heart, respectively. After the animals were killed, the tracheal cartilage, tracheal muscle-mucosa, and main bronchi were excised. The tracheal cartilage and tracheal muscle-mucosa were divided into lower, middle, and upper segments for blood flow determinations. The pulmonary contribution to tracheal blood flow was very small, averaging only 0.6 +/- 0.3 ml.min-1.100 g-1 (means +/- SE), being higher in the lower segments. The systemic contribution to these same tracheal regions was significantly (P less than 0.05) higher, averaging 20.9 +/- 5.5 ml.min-1.100 g-1 (means +/- SE) and higher in the upper segments. The pulmonary and systemic circulations each contributed approximately 50% to the main bronchi blood flow, which averaged 11.2 +/- 4.2 ml.min-1.100 g-1 (means +/- SE). The pulmonary blood flow contribution alone to the trachea and main bronchi was also determined in subsequent experiments that utilized the isolated lung, and these blood flows were not significantly different from the pulmonary contribution measured in the intact lungs. The present results indicate that the systemic (bronchial) circulation is the primary source of tracheal blood flow and that both the pulmonary and systemic circulations may contribute approximately 50% of the blood flow to the main bronchi in dog lungs.

Effects of pulmonary blood flow on the fractal nature of flow heterogeneity in sheep lungs

1994 ◽  
Vol 77 (3) ◽  
pp. 1474-1479 ◽  
Author(s):  
S. D. Caruthers ◽  
T. R. Harris
Keyword(s):  
Blood Flow ◽  
Pulmonary Blood Flow ◽  
Flow Distribution ◽  
Random Order ◽  
Portion Size ◽  
Relative Dispersion ◽  
Fractal Nature ◽  
Total Flow ◽  
Blood Flows

The spatial heterogeneity of pulmonary blood flow can be described by the relative dispersion (RD) of weight-flow histograms (RD = SD/mean). Glenny and Robertson (J. Appl. Physiol. 69: 532–545, 1990) showed that RD of flow in the lung is fractal in nature, characterized by the fractal dimension (D) and RD for the smallest realizable volume element (RDref). We studied the effects of increasing total pulmonary blood flow on D and RDref. In eight in situ perfused sheep lung preparations, 15-microns radio-labeled microspheres were injected into the pulmonary artery at five different blood flows ranging, in random order, from 1.5 to 5.0 l/m. The lungs were in zone 2 at the lower flows and in zone 3 at the higher flows. The lungs were removed, dried, cut into 2 x 2 x 2-cm3 pieces, weighed, and then counted for microsphere radioactivity. Fractal plots of log(weight) vs. log(RD) were constructed by iteratively combining neighboring pieces and then calculating RD with the increasingly larger portion size. D, which is one minus the slope of the fit through this plot, was 1.14 +/- 0.09 and did not change as blood flow increased. However, RDref decreased significantly (P < 0.01) as total flow increased. We conclude that the fractal nature of pulmonary blood flow distribution is not altered by changes in overall flow.

Persistent right coronary flow reserve at low perfusion pressure

1989 ◽  
Vol 256 (4) ◽  
pp. H1176-H1184 ◽  
Author(s):  
H. Murakami ◽  
S. J. Kim ◽  
H. F. Downey
Keyword(s):  
Blood Flow ◽  
Coronary Flow Reserve ◽  
Coronary Flow ◽  
Perfusion Pressure ◽  
Adenosine Infusion ◽  
Blood Flows ◽  
Flow Reserve ◽  
Anesthetized Dogs ◽  
Myocardial O2 Consumption ◽  
O2 Supply

To determine whether right coronary (RC) flow reserve persists at perfusion pressures below the apparent autoregulatory range, the RC artery of 18 anesthetized dogs was cannulated and perfused at controlled pressures. RC blood flow (RCBF) fell from 65.3 +/- 6.1 to 33.7 +/- 2.3 ml.min-1.100 g-1 as RC perfusion pressure (RCPP) was reduced from 80 to 40 mmHg. At 40 mmHg, intracoronary adenosine increased RCBF by 97.9 +/- 10.6 ml.min-1.100 g-1 (P less than 0.001). RCBF fell to 9.5 +/- 1.7 ml.min-1.100 g-1 at 20 mmHg, and RCBF did not significantly increase during adenosine, although RC vasodilation was observed in four dogs. Regional right ventricular (RV) blood flows at RCPP of 80 and 40 mmHg were measured by radioactive microsphere technique. Before adenosine infusion, RCBF was distributed uniformly across the RV free wall at normal and low perfusion pressures. During adenosine infusion, blood flow in both regions increased significantly, but the flow reserve was greater in the subendocardial region at both normal and reduced pressures. RV myocardial O2 consumption (MVo2) was decreased significantly at 40 mmHg, however, there was no evidence of ischemia at this pressure, since the RV lactate extraction ratio was normal (n = 8). Thus RV O2 demand fell when RC O2 supply was reduced, although a flow reserve was available. RV MVo2 was restored to normal when right coronary flow reserve was mobilized by adenosine infusion. For RCBF from 65 to 365 ml.min-1.100 g-1, RC venous O2 content rose and RV MVo2 was essentially constant.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Modeling of pulsating blood flows for problems of optical coherent tomography in ophthalmology.

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
S.V. Frolov ◽  
◽  
A.Yu. Potlov ◽  
S.G. Proskurin ◽  
T.A. Frolova ◽  
...  
Keyword(s):  
Blood Flow ◽  
Optical Coherence Tomography ◽  
Blood Vessels ◽  
Near Infrared ◽  
Anterior Segment ◽  
Medical Diagnostics ◽  
Multilayered Structure ◽  
Optical Coherence ◽  
Blood Flows ◽  
Liquid Silicone

Optical coherence tomography (OCT) is a method of non-invasive medical diagnostics based on scanning a biological object with near-infrared radiation, followed by registration and analysis of the back-reflected and back-scattered photons. The most of OCT systems are used in ophthalmology for diagnostics conditions of the retina, optic nerve and anterior segment of the eye. The purpose of this research is to increase the reliability of controlled experiments of the retina using phantoms by taking into account the partial clamping and vibrations of the walls of blood vessels that occur in real living objects. Methods of a retinal phantom molding containing special cavities (mimicking blood vessels) suitable for pumping blood-imitating fluid are described. The retina is shaped as a multilayered structure. Two-component transparent liquid silicone is used as to mold each layer. Indian ink with known optical properties is used to mimic absorption. Titanium dioxide particles are used as scatterers. The layers are formed sequentially from the bottom (choroid) to the top (inner boundary membrane). Mass fractions of the additives, as well as the thickness of each layer, are chosen on an individual basis. All blood vessels are represented as elongated and connected cavities. The formation of the base and complex network of the molded blood vessels is performed using a 3D printer. A device for making the palatial blood flow in phantoms of the retina, containing imitators of blood vessels and a pump with an adjustable flow velocity for pumping blood-imitating fluid, electric motors and a vibration motor for adjustable deformations and vibrations of the flexible tube walls is presented. When the characteristics of the pump and vibration motor are changed, turbulence is created after the formed laminar flow in the microtubes, which increases quality and blood flow reliability of the phantoms. Series of experiments applying the developed technique and the vessel phantoms with pulsating flow have been carried out using the method of optical coherence tomography. The developed phantoms and the controller can be used to test ophthalmic ultrasound and OCT systems for biomedical studies as well as to develop and adjust new modifications of the OCT imaging.

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