Periodic hemodynamics in skeletal muscle during local arterial pressure reduction

1992 ◽  
Vol 73 (3) ◽  
pp. 1077-1083 ◽  
Author(s):  
J. A. Schmidt ◽  
M. Intaglietta ◽  
P. Borgstrom
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Arterial Pressure ◽  
Slow Wave ◽  
Control Period ◽  
Wave Flow ◽  
Median Frequency ◽  
Doppler Flowmetry ◽  
Arterial Blood ◽  
Flow Motion

The time-dependent features of red blood cell flow were evaluated with laser-Doppler flowmetry (LDF) in the left gastrocnemius muscle of 31 anesthetized New Zealand White rabbits during stepwise arterial occlusion. During the control period with a median femoral pressure of 72 mmHg, 29 animals showed minor irregular fluctuations in LDF blood flow, and only two animals displayed periodic variations of blood flow. Lowering femoral arterial pressure induced maximal periodic blood flow variations at a median pressure of 35 mmHg in all animals with a median frequency of 1.5 cycles/min (termed “slow-wave flow motion”). The median amplitude was 48% of the corresponding average flow. These slow waves disappeared at a median femoral pressure of 20 mmHg. The median LDF flow value was 4.00 arbitrary units (AU) at control pressure and 2.05 AU at maximum slow-wave flow motion. When slow-wave flow motion was seen at several pressure levels, their frequency was identical, which supports the local pacemaker concept. This study promotes a novel concept for the role and physiological significance of periodic hemodynamics in that it is a condition not characteristic for normal control situations but is activated below a specific local arterial blood pressure and flow threshold, which is known to be the lower end of autoregulation in the microcirculation of rabbit skeletal muscle. This also suggests that slow-wave flow motion is primarily under local control mechanisms.

Assessment of muscle blood flow by laser-Doppler flowmetry during hemorrhage in SHR

1990 ◽  
Vol 259 (3) ◽  
pp. H860-H865
Author(s):  
J. H. Lombard ◽  
R. J. Roman
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Laser Doppler Flowmetry ◽  
Muscle Blood Flow ◽  
Control Period ◽  
Tissue Perfusion ◽  
Gracilis Muscle ◽  
Laser Doppler ◽  
Doppler Flowmetry ◽  
Skeletal Muscle Blood Flow

Skeletal muscle blood flow was assessed via laser-Doppler flowmetry (LDF) in the gracilis muscle of anesthetized 12- to 15-wk-old spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) control rats subjected to graded hemorrhage. Tissue perfusion was assessed at 20 specific sites in the muscle before and 20 min after each of five successive 1-ml withdrawals of blood. Mean LDF signals recorded from the gracilis muscle of SHR and WKY were similar during the prehemorrhage control period. After hemorrhage, mean arterial pressure and calculated vascular resistance of the gracilis muscle were higher in SHR than in WKY, and SHR exhibited a greater reduction of LDF signal in response to hemorrhage than WKY. Although SHR and WKY had a similar number of low flow sites (LDF signal less than 0.17 V) during the control period, successive blood volume withdrawals led to a significantly greater increase in the number of poorly perfused areas in the muscles of the hypertensive animals. The results of this study suggest that LDF is a useful tool to assess tissue perfusion during circulatory stress and that hemorrhage causes a greater decrease in skeletal muscle blood flow in SHR than in WKY. More severe reductions in tissue perfusion may contribute to the reduced ability of hypertensive animals to survive after hypotensive hemorrhage.

scholarly journals Regulation of Optic Nerve Head Blood Flow during Combined Changes in Intraocular Pressure and Arterial Blood Pressure

2013 ◽  
Vol 33 (12) ◽  
pp. 1850-1856 ◽  
Author(s):  
Agnes Boltz ◽  
Doreen Schmidl ◽  
René M Werkmeister ◽  
Michael Lasta ◽  
Semira Kaya ◽  
...  
Keyword(s):  
Blood Flow ◽  
Intraocular Pressure ◽  
Mean Arterial Pressure ◽  
Optic Nerve ◽  
Arterial Pressure ◽  
Optic Nerve Head ◽  
Isometric Exercise ◽  
Doppler Flowmetry ◽  
Ocular Perfusion ◽  
Arterial Blood

In the choroid, there is evidence that blood flow does not only depend on ocular perfusion pressure (OPP), but also on absolute mean arterial pressure (MAP) and intraocular pressure (IOP). The present study included 40 healthy subjects to investigate whether such behavior is also found in the optic nerve head (ONH). The ONH blood flow (ONHBF) was studied using laser Doppler flowmetry during a separate increase in IOP and MAP as well as during a combined elevation. Mean arterial pressure was increased by isometric exercise and IOP by the suction method. During both, the change in ONHBF was less pronounced than the change in OPP indicating autoregulation. Correlation analysis was performed for the combined experiments after pooling all data according to IOP and MAP values. A correlation between ONHBF and MAP was found at IOPs 25 mm Hg ( P<0.001), but not at IOPs>25 mm Hg ( P=0.79). Optic nerve head blood flow and IOP were significantly correlated ( P<0.001), and ONHBF was only slightly dependent on MAP. The data of the present study indicate a complex regulation of ONHBF during combined changes in MAP and IOP. Our results may be compatible with myogenic mechanisms underlying autoregulation, and indicate better ONHBF regulation during an increase in MAP than during an increase in IOP.

Effects of long-term vasopressin receptor stimulation on medullary blood flow and arterial pressure

1998 ◽  
Vol 275 (5) ◽  
pp. R1420-R1424 ◽  
Author(s):  
Allen W. Cowley ◽  
Meredith M. Skelton ◽  
Theresa M. Kurth
Keyword(s):  
Blood Flow ◽  
Arterial Pressure ◽  
Receptor Agonist ◽  
Long Term Effects ◽  
Doppler Flowmetry ◽  
Medullary Blood Flow ◽  
Arterial Blood ◽  
Sustained Reduction ◽  
Stimulation Of

Studies were carried out using instrumented unanesthetized rats to determine the long-term effects of arginine vasopressin (AVP) and a specific vasopressin V1 receptor agonist (V1AG; [Phe2, Ile3, Orn8]- vasopressin) on the renal medullary blood flow and arterial blood pressure. It was hypothesized that the hypertension observed with chronic medullary infusion of a V1 receptor agonist may be associated with a sustained reduction of blood flow, whereas infusion of AVP may fail to produce a sustained reduction of blood flow and thereby be unable to produce hypertension. Uninephrectomized Sprague-Dawley rats were prepared with implanted renal cortical and medullary optical fibers for daily measurements of cortical and medullary blood flow using laser-Doppler flowmetry techniques. An implanted renal medullary interstitial infusion catheter delivered either AVP or a specific V1AG at a dose of 2 ng ⋅ kg−1 ⋅ min−1over a period of 5 days. The V1AG produced no change of cortical blood flow but a chronic 35% reduction of medullary blood flow ( P < 0.05) and mild hypertension (11 ± 4 mmHg, P < 0.05). AVP produced only an initial, nonsignificant 1- to 2-day reduction of medullary blood flow (−13%) and failed to raise arterial pressure significantly. We conclude that a sustained V1AG response is necessary to achieve a chronic reduction of medullary blood flow and hypertension. The present data are consistent with the idea that chronic stimulation of V2receptors by AVP offsets the vasoconstrictor and hypertension actions of AVP-induced stimulation of medullary V1 receptors.

Abstract 9934: High Mean Arterial Pressure Aggravates Cerebral Hemodynamics After Extracorporeal Resuscitation in Swine

Circulation ◽  
2021 ◽  
Vol 144 (Suppl_2) ◽  
Author(s):  
Yael Levy ◽  
Alice Hutin ◽  
Nicolas Polge ◽  
fanny lidouren ◽  
Matthias Kohlhauer ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cardiac Arrest ◽  
Oxygen Consumption ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Cerebral Hemodynamics ◽  
Reactivity Index ◽  
Extracorporeal Cardiopulmonary Resuscitation ◽  
Standard Map ◽  
Arterial Blood

Introduction: Extracorporeal cardiopulmonary resuscitation (E-CPR) is used for the treatment of refractory cardiac arrest but the optimal target to reach for mean arterial pressure (MAP) remains to be determined. Hypothesis: We hypothesized that MAP levels modify cerebral hemodynamics during E-CPR. Accordingly, we tested two MAP targets (65-75 vs 80-90 mmHg) in a porcine model of E-CPR. Methods: Pigs were anesthetized and instrumented for the evaluation of cerebral and systemic hemodynamics. They were submitted to 15 min of untreated ventricular fibrillation followed by 30 min of E-CPR. Electric attempts of defibrillation were then delivered until resumption of spontaneous circulation (ROSC). Extracorporeal circulation was initially set to an average flow of 40 ml/kg/min with a standardized volume expansion in both groups. The dose of epinephrine was set to reach either a standard or a high MAP target level (65-75 vs 80-90 mmHg, respectively). Animals were followed during 120 min after ROSC. Results: Six animals were included in both groups. After cardiac arrest, MAP was maintained at the expected level (Figure). During E-CPR, high MAP transiently improved carotid blood flow as compared to standard MAP. This blood flow progressively decreased after ROSC in high vs standard MAP, while intra-cranial pressure increased. Interestingly, this was associated with a significant decrease in cerebral oxygen consumption (26±8 vs 54±6 L O 2 /min/kg at 120 min after ROSC, respectively; p<0.01) (Figure). The pressure reactivity index (PRx), which is the correlation coefficient between arterial blood pressure and intracranial pressure, became positive in high MAP (0.47±0.02) vs standard MAP group (-0.16±0.10), demonstrating altered cerebral autoregulation with high MAP. Conclusion: Increasing MAP above 80 mmHg with epinephrine aggravates cerebral hemodynamics after E-CPR. Figure: Mean arterial pressure (MAP), cerebral blood flow and oxygen consumption (*, p<0.05)

Increased vascular resistance in paralyzed legs after spinal cord injury is reversible by training

2002 ◽  
Vol 93 (6) ◽  
pp. 1966-1972 ◽  
Author(s):  
Maria T. E. Hopman ◽  
Jan T. Groothuis ◽  
Marcel Flendrie ◽  
Karin H. L. Gerrits ◽  
Sibrand Houtman
Keyword(s):  
Blood Pressure ◽  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Blood Flow ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Vascular Resistance ◽  
Arterial Blood Flow ◽  
Arterial Blood ◽  
Cord Injury

The purpose of the present study was to determine the effect of a spinal cord injury (SCI) on resting vascular resistance in paralyzed legs in humans. To accomplish this goal, we measured blood pressure and resting flow above and below the lesion (by using venous occlusion plethysmography) in 11 patients with SCI and in 10 healthy controls (C). Relative vascular resistance was calculated as mean arterial pressure in millimeters of mercury divided by the arterial blood flow in milliliters per minute per 100 milliliters of tissue. Arterial blood flow in the sympathetically deprived and paralyzed legs of SCI was significantly lower than leg blood flow in C. Because mean arterial pressure showed no differences between both groups, leg vascular resistance in SCI was significantly higher than in C. Within the SCI group, arterial blood flow was significantly higher and vascular resistance significantly lower in the arms than in the legs. To distinguish between the effect of loss of central neural control vs. deconditioning, a group of nine SCI patients was trained for 6 wk and showed a 30% increase in leg blood flow with unchanged blood pressure levels, indicating a marked reduction in vascular resistance. In conclusion, vascular resistance is increased in the paralyzed legs of individuals with SCI and is reversible by training.

Vasoactive intestinal polypeptide reduces hydrochloric acid-induced duodenal mucosal permeability

1993 ◽  
Vol 264 (2) ◽  
pp. G272-G279 ◽  
Author(s):  
O. Nylander ◽  
E. Wilander ◽  
G. M. Larson ◽  
L. Holm
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Vasoactive Intestinal Polypeptide ◽  
Lesion Score ◽  
Morphological Examination ◽  
Mucosal Permeability ◽  
Doppler Flowmetry ◽  
Arterial Blood ◽  
51Cr Edta ◽  
Intestinal Polypeptide

The duodenum in anesthetized rats was perfused with HCl, and mucosal integrity was assessed by measuring the clearance of 51Cr-labeled EDTA from blood to lumen and/or by morphological examination (lesion score). Duodenal blood flow was determined by laser Doppler flowmetry and luminal alkalinization as well as H+ disappearance by backtitration. Intravenous infusion of vasoactive intestinal polypeptide (VIP; 13.5 micrograms.kg-1.h-1) increased luminal alkalinization threefold and decreased clearance of 51Cr-EDTA by 50%. VIP also decreased arterial blood pressure and induced a small and irregular decrease in duodenal blood flow. Perfusion with 10 mM HCl increased clearance of 51Cr-EDTA 2.1-fold, but the lesion score was not different from that in saline-perfused animals. Perfusion with 20 mM HCl increased clearance of 51Cr-EDTA four-fold and induced a greater lesion score than did 10 mM. Perfusion with either 10 or 20 mM HCl did not affect the duodenal blood flow. VIP reduced the rise in clearance of 51Cr-EDTA in response to 10 mM but not that to 20 mM HCl. Intravenous injection of prazosin (50 micrograms/kg) decreased luminal alkalinization, clearance of 51Cr-EDTA, blood pressure, and duodenal blood flow. In prazosin-pretreated rats, perfusion with 10 mM HCl increased clearance of 51Cr-EDTA 2.6-fold, and the lesion score was greater in this group than in animals infused with VIP. A positive linear correlation was obtained between HCO3- secretion and the mean rate of H+ disappearance.(ABSTRACT TRUNCATED AT 250 WORDS)

Microvascular pressure in venules of skeletal muscle during arterial pressure reduction

1986 ◽  
Vol 250 (5) ◽  
pp. H838-H845 ◽  
Author(s):  
S. D. House ◽  
P. C. Johnson
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Arterial Pressure ◽  
Pressure Gradient ◽  
Pressure Difference ◽  
Reactive Hyperemia ◽  
Sartorius Muscle ◽  
Pressure Reduction ◽  
Large Vein ◽  
The Difference

It has been suggested from whole organ studies that the viscosity of blood in skeletal muscle venules varies inversely with flow over physiological flow ranges. If this is the case, the hydrostatic pressure gradient in venules should change less than flow as flow is altered. To test this hypothesis, pressure in venules of cat sartorius muscle was measured during stepwise arterial pressure reduction to 20 mmHg. Large vein pressure remained constant at about 5 mmHg. Average pressures in the large venules (40–185 microns) ranged from 13.6 to 10.0 mmHg. The difference between pressure in these venules and large vein pressure fell in proportion to the reduction in blood pressure and blood flow. Pressures in the smallest venules studied (25 microns) averaged 19.7 +/- 6.2 (SD) mmHg. The pressure difference between the smallest venules and the large vein fell less than the arteriovenous pressure difference or blood flow when arterial pressure was reduced. During reactive hyperemia the pressure gradient between the smallest venules and the large vein rose proportionately less than blood flow. The stability of pressure in the smallest venules is consistent with the hypothesis that blood viscosity varies inversely with flow rate.

scholarly journals PL - 031 Skeletal muscle blood flow determination using gold standard invasive arterial input function and non-invasive image-based input function by positron emission tomography (PET)

2018 ◽  
Vol 1 (1) ◽  
Author(s):  
Ilkka Heinonen ◽  
Kari Kalliokoski ◽  
Vesa Oikonen ◽  
Christopher Mawhinney ◽  
Warren Gregson ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Data Analysis ◽  
Arterial Input Function ◽  
Muscle Blood Flow ◽  
Input Function ◽  
Invasive Approach ◽  
Skeletal Muscle Blood Flow ◽  
Non Invasive ◽  
Arterial Blood

Objective Skeletal muscle is unique among organs in that its blood flow, thus oxygen supply that is critical for muscular function, can change over a remarkably large range. Compared to the rest, muscle blood flow can increase over 20-fold during intense exercise. Positron emission tomography (PET) and [15O]-H2O tracer provide a unique tool for the direct measurement of muscle blood flow in specific muscle regions. Quantification of PET blood flow requires knowledge of the arterial input function, which is usually provided by arterial blood sampling. However, arterial sampling is an invasive approach requiring arterial cannulation. In the current study, we aimed to explore the analysis and error estimation based on non-invasive, PET image-based input function for skeletal muscle blood flow in PET [15O]-labeled radiowater study. Methods Thirty healthy untrained men volunteered to participate in this study. [15O]-labeled radio water PET perfusion scans were performed at rest and right after cycling exercise. GE Discovery PET-CT scanner was used for image acquisition. The 15O isotope was produced with a Cyclone 3 cyclotron (IBA Molecular, Belgium). After 455 MBq of 15O-H2O was injected intravenously and after 20 seconds, dynamic scanning images were performed in following frames: 6x5 seconds, 12x10 seconds, 7x30 seconds and 12x10 seconds. Arterial blood was sampled continuously from radial artery during imaging for radioactivity with a detector during PET scanning. All the data analysis was performed using all in-house developed programs. Arterial input function was preprocessed with delay correction. Image-based input function was defined based on sum image of dynamic images. Blood flow was calculated using the 1-tissue compartment model, k1 is considered as blood flow without any further correction. All data analysis was performed by Carimas software (http://www.turkupetcentre.fi/carimas). Data analysis was performed in five parts: 1) Modelling data using input function from artery. 2) By defining femoral artery Volume Of Interest (VOI) on PET images. 3) Modelling data using image-based input function. 4) Calculating the correlation for blood flow between artery (blood) input function and image-based input function. 5) Predicted true blood flow was calculated based on correlation based on the initial linear relationship between blood and image-based input functions. Results Skeletal muscle blood flow had a good linear relationship calculated by femoral artery VOI and by arterial (blood) input function (y = 2,9587x - 0,096, R² = 0,8852, p<0.0001). Further, by using the prediction equation obtained by the linear relationship between VOI-determined (femoral) artery blood flow and direct gold standard (radial) artery input function determined blood flow, image-based input function determined blood flow was well predicted using this non-invasive approach (y = 1,1812x + 0,1219, R² = 0,9259, p<0.0001). Conclusions It is concluded that there is a strong linear correlation between gold standard invasive approach and non-invasive image-based approach to measure skeletal muscle blood flow by PET, but if no further corrections are made, image-based approach overestimates correct blood flow. However, this can be corrected by linear prediction equation, suggesting that invasive arterial input function may not always be needed in the future when measuring skeletal muscle blood flow by PET. This will be of benefit particularly for exercise studies.

Tubuloglomerular feedback dynamics and renal blood flow autoregulation in rats

1991 ◽  
Vol 260 (1) ◽  
pp. F53-F68 ◽  
Author(s):  
N. H. Holstein-Rathlou ◽  
A. J. Wagner ◽  
D. J. Marsh
Keyword(s):  
Blood Flow ◽  
Arterial Pressure ◽  
Renal Blood Flow ◽  
Slow Component ◽  
Broad Band ◽  
Experimental Results ◽  
Tubuloglomerular Feedback ◽  
Single Frequency ◽  
Vascular Control ◽  
Arterial Blood

To decide whether tubuloglomerular feedback (TGF) can account for renal autoregulation, we tested predictions of a TGF simulation. Broad-band and single-frequency perturbations were applied to arterial pressure; arterial blood pressure, renal blood flow and proximal tubule pressure were measured. Data were analyzed by linear systems analysis. Broad-band forcings of arterial pressure were also applied to the model to compare experimental results with simulations. With arterial pressure as the input and tubular pressure, renal blood flow, or renal vascular resistance as outputs, the model correctly predicted gain and phase only in the low-frequency range. Experimental results revealed a second component of vascular control active at 100-150 mHz that was not predicted by the simulation. Forcings at single frequencies showed that the system behaves linearly except in the band of 33-50 mHz in which, in addition, there are autonomous oscillations in TGF. Higher amplitude forcings in this band were attenuated by autoregulatory mechanisms, but low-amplitude forcings entrained the autonomous oscillations and provoked amplified oscillations in blood flow, showing an effect of TGF on whole kidney blood flow. We conclude that two components can be detected in the dynamic regulation of renal blood flow, i.e., a slow component that represents TGF and a faster component that most likely represents an intrinsic vascular myogenic mechanism.

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