Photoacoustic Imaging for the Detection of Hypoxia in the Rat Femoral Artery and Skeletal Muscle Microcirculation

Although blood flow in the microcirculation of the rat skeletal muscle has negligible inertia forces with very low Reynolds number and Womersley parameter, time-dependent pressure and flow variations can be observed. Such phenomena include, for example, arterial flow overshoot following a step arterial pressure, a gradual arterial pressure reduction for a step flow, or hysteresis between pressure and flow when a pulsatile pressure is applied. Arterial and venous flows do not follow the same time course during such transients. A theoretical analysis is presented for these phenomena using a microvessel with distensible viscoelastic walls and purely viscous flow subject to time variant arterial pressures. The results indicate that the vessel distensibility plays an important role in such time-dependent microvascular flow and the effects are of central physiological importance during normal muscle perfusion. In-vivo whole organ pressure-flow data in the dilated rat gracilis muscle agree in the time course with the theoretical predictions. Hemodynamic impedances of the skeletal muscle microcirculation are investigated for small arterial and venous pressure amplitudes superimposed on an initial steady flow and pressure drop along the vessel.

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Dynamic viscous flow in distensible vessels of skeletal muscle microcirculation: Application to pressure and flow transients

Biorheology ◽

10.3233/bir-1989-26209 ◽

1989 ◽

Vol 26 (2) ◽

pp. 215-227 ◽

Cited By ~ 11

Author(s):

G.W. Schmid-Schönbein ◽

S.Y. Lee ◽

D. Sutton

Keyword(s):

Skeletal Muscle ◽

Viscous Flow ◽

Skeletal Muscle Microcirculation ◽

Flow Transients

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Coordinated diameter oscillations at arteriolar bifurcations in skeletal muscle

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1987.253.3.h568 ◽

1987 ◽

Vol 253 (3) ◽

pp. H568-H573 ◽

Cited By ~ 5

Author(s):

J. U. Meyer ◽

L. Lindbom ◽

M. Intaglietta

Keyword(s):

Skeletal Muscle ◽

Fundamental Frequency ◽

Narrow Band ◽

Photometric System ◽

Band Frequency ◽

Skeletal Muscle Microcirculation

The spontaneous rhythmical luminal changes (vasomotion) at bifurcations in the microvasculature of the rabbit tenuissimus muscle were investigated by means of a microscope video photometric system. Video scenes, containing two terminal arterioles originating from one transverse arteriole, showed that adjacent terminal arterioles constricted synchronously in 26 out of 31 contraction cycles. The onset of 60 constrictions in the parent transverse vessels was synchronized with the activity in terminal arterioles in 75% of the cycles and delayed in 25%. Vasomotion in the parent transverse vessels was notably smaller than in the terminal vessels. All the terminal arterioles in the different animals oscillated at the fundamental frequency of 18.9 +/- 3.5 cycles/min. We conclude that in the skeletal muscle microcirculation 1) coordinated spontaneous diameter oscillations occur in arterioles that are in proximity, 2) diameter changes are most pronounced in the terminal arterioles, and 3) coordinated vasomotion in this tissue exhibits a characteristic narrow band frequency. The presence of a microvascular pacemaker is hypothesized.

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Endothelial Control of Shear Stress and Resistance in the Skeletal Muscle Microcirculation

Flow-Dependent Regulation of Vascular Function ◽

10.1007/978-1-4614-7527-9_11 ◽

1995 ◽

pp. 236-260 ◽

Cited By ~ 5

Author(s):

Akos Koller ◽

Gabor Kaley

Keyword(s):

Skeletal Muscle ◽

Shear Stress ◽

Skeletal Muscle Microcirculation ◽

Endothelial Control

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Aerobic Exercise Attenuates Pressure Overload-Induced Cardiac Dysfunction through Promoting Skeletal Muscle Microcirculation and Increasing Muscle Mass

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2021/8279369 ◽

2021 ◽

Vol 2021 ◽

pp. 1-11

Author(s):

Ling-Yan Yuan ◽

Pei-Zhao Du ◽

Min-Min Wei ◽

Qi Zhang ◽

Le Lu ◽

...

Keyword(s):

Skeletal Muscle ◽

Cardiac Function ◽

Aerobic Exercise ◽

Muscle Mass ◽

Cardiac Dysfunction ◽

Pressure Overload ◽

Transverse Aortic Constriction ◽

Aortic Constriction ◽

Protein Levels ◽

Skeletal Muscle Microcirculation

Background. Aerobic exercise has been proven to have a positive effect on cardiac function after hypertension; however, the mechanism is not entirely clarified. Skeletal muscle mass and microcirculation are closely associated with blood pressure and cardiac function. Objective. This study was designed to investigate the effects of aerobic exercise on the skeletal muscle capillary and muscle mass, to explore the possible mechanisms involved in exercise-induced mitigation of cardiac dysfunction in pressure overload mice. Methods. In this study, 60 BALB/C mice aged 8 weeks were randomly divided into 3 groups: control (CON), TAC, and TAC plus exercise (TAE) group and utilized transverse aortic constriction (TAC) to establish hypertensive model; meanwhile, treadmill training is used for aerobic exercise. After 5 days of recovery, mice in the TAE group were subjected to 10-week aerobic exercise. Carotid pressure and cardiac function were examined before mice were executed by Millar catheter and ultrasound, respectively. Muscle mass of gastrocnemius was weighed; cross-sectional area and the number of capillaries of gastrocnemius were detected by HE and immunohistochemistry, respectively. The mRNA and protein levels of VEGF in skeletal muscle were determined by RT-PCR and western blot, respectively. Results. We found that ① 10-week aerobic exercise counteracted hypertension and attenuated cardiac dysfunction in TAC-induced hypertensive mice; ② TAC decreased muscle mass of gastrocnemius and resulted in muscle atrophy, while 10-week aerobic exercise could reserve transverse aortic constriction-induced the decline of muscle mass and muscle atrophy; and ③ TAC reduced the number of capillaries and the protein level of VEGF in gastrocnemius, whereas 10-week aerobic exercise augmented the number of capillaries, the mRNA and protein levels of VEGF in mice were subjected to TAC surgery. Conclusions. This study indicates that 10-week aerobic exercise might fulfill its blood pressure-lowering effect via improving skeletal muscle microcirculation and increasing muscle mass.

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Impaired skeletal muscle microcirculation in systemic sclerosis

Arthritis Research & Therapy ◽

10.1186/ar4047 ◽

2012 ◽

Vol 14 (5) ◽

pp. R209 ◽

Cited By ~ 22

Author(s):

Sasan Partovi ◽

Anja-Carina Schulte ◽

Markus Aschwanden ◽

Daniel Staub ◽

Daniela Benz ◽

...

Keyword(s):

Skeletal Muscle ◽

Systemic Sclerosis ◽

Skeletal Muscle Microcirculation

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Postprandial heat production in skeletal muscle is associated with altered mitochondrial function and altered futile calcium cycling

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00036.2012 ◽

2012 ◽

Vol 303 (10) ◽

pp. R1071-R1079 ◽

Cited By ~ 15

Author(s):

Scott D. Clarke ◽

Kevin Lee ◽

Zane B. Andrews ◽

Robert Bischof ◽

Fahri Fahri ◽

...

Keyword(s):

Skeletal Muscle ◽

Blood Flow ◽

Femoral Artery ◽

Heat Production ◽

Mitochondrial Function ◽

Uncoupling Protein ◽

Vastus Lateralis Muscle ◽

Muscle Temperature ◽

Calcium Cycling ◽

Doppler Flowmetry

This study aimed to determine whether postprandial temperature excursions in skeletal muscle are consistent with thermogenesis or altered blood flow. Temperature probes were implanted into the vastus lateralis muscle of ovariectomized ewes, and blood flow was assessed using laser-Doppler flowmetry (tissue flow) and transit-time ultrasound flowmetry (femoral artery flow). The animals were program-fed between 1100 and 1600, and temperature and blood flow were measured during intravenous administration of either isoprenaline or phenylephrine and during feeding and meal anticipation. In addition, muscle biopsies were collected prefeeding and postfeeding to measure uncoupling protein (UCP) expression and mitochondrial function, as well as indices of calcium cycling (ryanodine 1 receptor: RyR1 and sarcoendoplasmic calcium-dependent ATPases SERCA1/ SERCA2a). Isoprenaline increased femoral artery blood flow, whereas phenylephrine reduced blood flow. At high doses only, isoprenaline treatment increased heat production in muscle. Phenylephrine treatment did not alter muscle temperature. Meal anticipation was evoked in fasted animals (previously program-fed) that were housed beside animals that were fed. Increases in muscle temperature were elicited by feeding and meal anticipation, without changes in blood flow during either paradigm. Analyses of respiration in isolated mitochondria indicated that the postprandial increase in heat production was associated with an increase in state 4 respiration, without increased UCP1, UCP2, or UCP3 expression. Feeding increased the expression of RyR1 and SERCA2a. We conclude that excursions in muscle temperature may occur independent of blood flow, suggesting that postprandial heat production is driven by altered mitochondrial function and changes in calcium cycling.

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Endothelium regulates skeletal muscle microcirculation by a blood flow velocity-sensing mechanism

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1990.258.3.h916 ◽

1990 ◽

Vol 258 (3) ◽

pp. H916-H920 ◽

Cited By ~ 32

Author(s):

A. Koller ◽

G. Kaley

Keyword(s):

Skeletal Muscle ◽

Endothelial Cells ◽

Blood Flow ◽

Flow Velocity ◽

Cremaster Muscle ◽

Positive Linear Correlation ◽

Skeletal Muscle Microcirculation ◽

Per Se ◽

Dependent Flow

In rat cremaster muscle, utilizing parallel arteriolar occlusion, we found that an increase in red blood cell (RBC) velocity (3.5-26.5 mm/s) per se induced an increase in diameter (1.5-9.4 microns) of arterioles (mean control diam 21.5 +/- 0.6 microns; n = 25). The dilation of arterioles appeared only when RBC velocity increased and started always with a delay (mean 8.4 +/- 0.5 s) after the increase in flow velocity. A positive linear correlation was found between peak changes in RBC velocity and diameter (r = 0.87, P less than 0.05). The velocity sensor as well as the mechanism(s) that mediates this response is likely to be located in endothelial cells, because the dilation to increased RBC velocity was completely eliminated after impairment of arteriolar endothelium with light-dye (L-D) treatment. The in vivo demonstration of this phenomenon in arterioles suggests the existence of a new endothelium-dependent, flow velocity-sensitive mechanism for the regulation of blood flow in the microcirculation.

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Bradykinin does not acutely sensitize the reflex pressor response during hindlimb skeletal muscle stretch in decerebrate rats

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00187.2017 ◽

2017 ◽

Vol 313 (4) ◽

pp. R463-R472 ◽

Cited By ~ 4

Author(s):

Korynne S. Rollins ◽

Joshua R. Smith ◽

Peter J. Esau ◽

Evan A. Kempf ◽

Tyler D. Hopkins ◽

...

Keyword(s):

Blood Pressure ◽

Skeletal Muscle ◽

Femoral Artery ◽

Sympathetic Nerve ◽

Sympathetic Nerve Activity ◽

Pressor Response ◽

Nerve Activity ◽

Muscle Stretch ◽

Renal Sympathetic Nerve Activity ◽

Hindlimb Muscle

Hindlimb skeletal muscle stretch (i.e., selective activation of the muscle mechanoreflex) in decerebrate rats evokes reflex increases in blood pressure and sympathetic nerve activity. Bradykinin has been found to sensitize mechanogated channels through a bradykinin B2 receptor-dependent mechanism. Moreover, bradykinin B2 receptor expression on sensory neurons is increased following chronic femoral artery ligation in the rat (a model of simulated peripheral artery disease). We tested the hypothesis that injection of bradykinin into the arterial supply of a hindlimb in decerebrate, unanesthetized rats would acutely augment (i.e., sensitize) the increase in blood pressure and renal sympathetic nerve activity during hindlimb muscle stretch to a greater extent in rats with a ligated femoral artery than in rats with a freely perfused femoral artery. The pressor response during static hindlimb muscle stretch was compared before and after hindlimb arterial injection of 0.5 µg of bradykinin. Injection of bradykinin increased blood pressure to a greater extent in “ligated” ( n = 10) than “freely perfused” ( n = 10) rats. The increase in blood pressure during hindlimb muscle stretch, however, was not different before vs. after bradykinin injection in freely perfused (14 ± 2 and 15 ± 2 mmHg for pre- and post-bradykinin, respectively, P = 0.62) or ligated (15 ± 3 and 14 ± 2 mmHg for pre- and post-bradykinin, respectively, P = 0.80) rats. Likewise, the increase in renal sympathetic nerve activity during stretch was not different before vs. after bradykinin injection in either group of rats. We conclude that bradykinin did not acutely sensitize the pressor response during hindlimb skeletal muscle stretch in freely perfused or ligated decerebrate rats.

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