scholarly journals Skeletal muscle contractions uncoupled from gravitational loading directly increase cortical bone blood flow rates in vivo

2008 ◽  
Vol 27 (5) ◽  
pp. 651-656 ◽  
Author(s):  
Carrie Caulkins ◽  
Edward Ebramzadeh ◽  
Howard Winet
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Cortical Bone ◽  
Muscle Contractions ◽  
Bone Blood Flow ◽  
Flow Rates ◽  
Gravitational Loading

scholarly journals Major differences in noradrenaline action on lipolysis and blood flow rates in skeletal muscle and adipose tissue in vivo

Diabetologia ◽  
2005 ◽  
Vol 48 (5) ◽  
pp. 946-953 ◽  
Author(s):  
V. Quisth ◽  
S. Enoksson ◽  
E. Blaak ◽  
E. Hagström-Toft ◽  
P. Arner ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Adipose Tissue ◽  
Flow Rates

No apparent suppression by insulin of in vivo skeletal muscle lipolysis in nonobese women

2002 ◽  
Vol 283 (2) ◽  
pp. E295-E301 ◽  
Author(s):  
Erik Moberg ◽  
Stefan Sjöberg ◽  
Eva Hagström-Toft ◽  
Jan Bolinder
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Adipose Tissue ◽  
Insulin Infusion ◽  
Muscle Blood Flow ◽  
Tissue Blood Flow ◽  
Glycerol Release ◽  
Euglycemic Hyperinsulinemic Clamp ◽  
Flow Rates

To investigate the antilipolytic effect of insulin in skeletal muscle and adipose tissue in vivo, the rates of glycerol release from the two tissues were compared in 10 nonobese women during a two-step euglycemic hyperinsulinemic clamp. Tissue interstitial glycerol levels were determined by microdialysis, and tissue blood flow was assessed with the 133Xe clearance technique. Absolute rates of glycerol release were estimated according to Fick's principle. In both adipose tissue and muscle, glycerol levels decreased significantly already during the low insulin infusion rate. The fractional release of glycerol (difference between interstitial glycerol and arterialized venous plasma glycerol) was reduced by more than one-half in adipose tissue ( P < 0.0001) in response to insulin, whereas it remained unaltered in skeletal muscle. Muscle blood flow rates increased by 60% ( P < 0.02) during insulin infusion; in adipose tissue, blood flow rates did not change significantly in response to insulin. The basal rate of glycerol release from skeletal muscle amounted to ∼15% of that from adipose tissue. After insulin infusion, the rate of adipose tissue glycerol release was markedly suppressed, whereas in skeletal muscle the rate of glycerol mobilization did not change significantly in response to insulin. It is concluded that insulin does not inhibit the rate of lipolysis in skeletal muscle of nonobese women.

scholarly journals Effects of aging and exercise training on spinotrapezius muscle microvascular Po2 dynamics and vasomotor control

2011 ◽  
Vol 110 (3) ◽  
pp. 695-704 ◽  
Author(s):  
Danielle J. McCullough ◽  
Robert T. Davis ◽  
James M. Dominguez ◽  
John N. Stabley ◽  
Christian S. Bruells ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Exercise Training ◽  
Sodium Nitroprusside ◽  
Vascular Function ◽  
Treadmill Running ◽  
Aged Rats ◽  
Phosphorescence Quenching

With advancing age, there is a reduction in exercise tolerance, resulting, in part, from a perturbed ability to match O2 delivery to uptake within skeletal muscle. In the spinotrapezius muscle (which is not recruited during incline treadmill running) of aged rats, we tested the hypotheses that exercise training will 1) improve the matching of O2 delivery to O2 uptake, evidenced through improved microvascular Po2 (PmO2), at rest and throughout the contractions transient; and 2) enhance endothelium-dependent vasodilation in first-order arterioles. Young (Y, ∼6 mo) and aged (O, >24 mo) Fischer 344 rats were assigned to control sedentary (YSED; n = 16, and OSED; n = 15) or exercise-trained (YET; n = 14, and OET; n = 13) groups. Spinotrapezius blood flow (via radiolabeled microspheres) was measured at rest and during exercise. Phosphorescence quenching was used to quantify PmO2 in vivo at rest and across the rest-to-twitch contraction (1 Hz, 5 min) transition in the spinotrapezius muscle. In a follow-up study, vasomotor responses to endothelium-dependent (acetylcholine) and -independent (sodium nitroprusside) stimuli were investigated in vitro. Blood flow to the spinotrapezius did not increase above resting values during exercise in either young or aged groups. Exercise training increased the precontraction baseline PmO2 (OET 37.5 ± 3.9 vs. OSED 24.7 ± 3.6 Torr, P < 0.05); the end-contracting PmO2 and the time-delay before PmO2 fell in the aged group but did not affect these values in the young. Exercise training improved maximal vasodilation in aged rats to acetylcholine (OET 62 ± 16 vs. OSED 27 ± 16%) and to sodium nitroprusside in both young and aged rats. Endurance training of aged rats enhances the PmO2 in a nonrecruited skeletal muscle and is associated with improved vascular smooth muscle function. These data support the notion that improvements in vascular function with exercise training are not isolated to the recruited muscle.

A malonyl-CoA fuel-sensing mechanism in muscle: effects of insulin, glucose, and denervation

1995 ◽  
Vol 269 (2) ◽  
pp. E283-E289 ◽  
Author(s):  
A. K. Saha ◽  
T. G. Kurowski ◽  
N. B. Ruderman
Keyword(s):  
Skeletal Muscle ◽  
Plasma Insulin ◽  
Contractile Activity ◽  
High Plasma ◽  
Muscle Contractions ◽  
Glucose Levels ◽  
Malonyl Coa ◽  
Ad Libitum ◽  
Sciatic Nerve Stimulation

Increases in the concentration of malonyl-CoA in skeletal muscle have been observed in the KKAy mouse, an obese rodent with high plasma insulin and glucose levels [Saha et al. Am. J. Physiol. 267 (Endocrinol. Metab. 30): E95-E101, 1994]. To assess whether insulin and glucose directly regulate malonyl-CoA in muscle, soleus muscles from young rats were incubated with insulin and glucose at various concentrations, and their content of malonyl-CoA was determined. In addition, the effect on malonyl-CoA of denervation and electrically induced muscle contractions was assessed. The concentration of malonyl-CoA in the soleus, taken directly from a rat fed ad libitum, was 2.0 +/- 0.2 nmol/g. In muscles incubated for 20 min in a medium devoid of added insulin and glucose, the concentration was decreased to 0.8 +/- 0.2 nmol/g. When the medium contained 0.5, 7.5, or 30 mM glucose, malonyl-CoA levels were 1.3 +/- 0.1, 1.8 +/- 0.1, or 2.4 +/- 0.2 nmol/g, respectively, in the absence of insulin and 1.7 +/- 0.1, 4.6 +/- 0.3, or 5.5 +/- 0.6 nmol/g in its presence (10 mU/ml). Compared with its level in a control muscle, the concentration of malonyl-CoA was increased threefold in the soleus 6-8 h after denervation and remained twofold higher for > or = 48 h. In contrast, muscle contractions induced by sciatic nerve stimulation, in vivo, acutely decreased the concentration of malonyl-CoA by 30-35%. The results indicate that insulin and glucose, and probably contractile activity, regulate the concentration of malonyl-CoA in muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Microdialysis of skeletal muscle at rest

1999 ◽  
Vol 58 (4) ◽  
pp. 919-923 ◽  
Author(s):  
Jan Henriksson
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Human Skeletal Muscle ◽  
Human Metabolism ◽  
High Expectations ◽  
Perfusate Flow ◽  
Muscle Research ◽  
Interstitial Glucose

Techniques in human skeletal muscle research are by necessity predominantly 'descriptive'.Microdialysis has raised high expectations that it could meet the demand for a method that allows 'mechanistic' investigations to be performed in human skeletal muscle. In the present review, some views are given on how well the initial expectations on the use of the microdialysis technique in skeletal muscle have been fulfilled, and the areas in which additional work is needed in order to validate microdialysis as an important metabolic technique in this tissue. The microdialysis catheter has been equated to an artificial blood vessel, which is introduced into the tissue. By means of this 'vessel' the concentrations of compounds in the interstitial space can be monitored. The concentration of substances in the collected samples is dependent on the rate of perfusate flow. When perfusate flow is slow enough to allow complete equilibration between interstitial and perfusate fluids, the concentration in the perfusate is maximal and identical to the interstitial concentration. Microdialysis data may be influenced by changes in blood flow, especially in instances where the tissue diffusivity limits the recovery in vivo, i.e. when recovery in vitro is 100 %, whereas the recovery in vivo is less than 100 %. Microdialysis data indicate that a significant arterial-interstitial glucose concentration gradient exists in skeletal muscle but not in adipose tissue at rest. While the concentrations of glucose and lactate in the dialysate from skeletal muscle are close to the expected values, the glycerol values obtained for muscle are still puzzling. Ethanol added to the perfusate will be cleared by the tissue at a rate that is determined by the nutritive blood flow (the microdialysis ethanol technique). It is concluded that microdialysis of skeletal muscle has become an important technique for mechanistic studies in human metabolism and nutrition.

scholarly journals Visualization of Mitochondrial Ca2+ Signals in Skeletal Muscle of Zebrafish Embryos with Bioluminescent Indicators

2019 ◽  
Vol 20 (21) ◽  
pp. 5409 ◽  
Author(s):  
Manuel Vicente ◽  
Jussep Salgado-Almario ◽  
Joaquim Soriano ◽  
Miguel Burgos ◽  
Beatriz Domingo ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Contractions ◽  
Zebrafish Embryos ◽  
Mitochondrial Matrix ◽  
Mitochondrial Calcium Uniporter ◽  
Calcium Uniporter ◽  
Skeletal Muscle Contraction ◽  
Spatio Temporal ◽  
Mitochondrial Uncoupler

Mitochondria are believed to play an important role in shaping the intracellular Ca2+ transients during skeletal muscle contraction. There is discussion about whether mitochondrial matrix Ca2+ dynamics always mirror the cytoplasmic changes and whether this happens in vivo in whole organisms. In this study, we characterized cytosolic and mitochondrial Ca2+ signals during spontaneous skeletal muscle contractions in zebrafish embryos expressing bioluminescent GFP-aequorin (GA, cytoplasm) and mitoGFP-aequorin (mitoGA, trapped in the mitochondrial matrix). The Ca2+ transients measured with GA and mitoGA reflected contractions of the trunk observed by transmitted light. The mitochondrial uncoupler FCCP and the inhibitor of the mitochondrial calcium uniporter (MCU), DS16570511, abolished mitochondrial Ca2+ transients whereas they increased the frequency of cytosolic Ca2+ transients and muscle contractions, confirming the subcellular localization of mitoGA. Mitochondrial Ca2+ dynamics were also determined with mitoGA and were found to follow closely cytoplasmic changes, with a slower decay. Cytoplasmic Ca2+ kinetics and propagation along the trunk and tail were characterized with GA and with the genetically encoded fluorescent Ca2+ indicator, Twitch-4. Although fluorescence provided a better spatio-temporal resolution, GA was able to resolve the same kinetic parameters while allowing continuous measurements for hours.

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

1990 ◽  
Vol 258 (3) ◽  
pp. H916-H920 ◽  
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.

Effects of intra-arterial arginine-vasopressin infusions on peripheral blood flows in conscious dogs

1986 ◽  
Vol 71 (6) ◽  
pp. 713-721 ◽  
Author(s):  
Jean-Francois Liard
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Small Intestine ◽  
Arginine Vasopressin ◽  
Muscle Blood Flow ◽  
Plasma Concentrations ◽  
Abdominal Fat ◽  
Conscious Dogs ◽  
Bone Blood Flow ◽  
Blood Flows

1. We reported in an earlier study that intravenous infusions of arginine-vasopressin (AVP), 220 pg min−1 kg−1 for 1 h, substantially reduced blood flow to the skin, skeletal muscle, pancreas, colon, small intestine, abdominal fat and myocardium [1] in conscious dogs. In the present study, we infused AVP directly into the artery supplying these organs and tissues in order to determine the relative contribution of local versus systemic mechanisms in the vascular resistance changes previously observed. 2. Regional blood flows were measured with radioactive microspheres in conscious, chronically instrumented dogs before and during intra-arterial infusions of AVP administered into the left axillary artery (n = 6), the left coronary artery (n = 6), and the cranial mesenteric artery (n = 6). The infusion rates were calculated to increase local, target organ plasma concentrations of AVP to the levels reached in our previous study while minimizing systemic changes. 3. Left axillary AVP artery infusion significantly reduced skin and compact bone blood flow, but had no effect on skeletal muscle blood flow. Intra-coronary AVP infusion had no effect on myocardial blood flow nor on cardiac output. Intramesenteric AVP infusion had no effect on blood flow to the colon, small intestine and abdominal fat, but significantly reduced blood flow to those areas of the pancreas which received blood from the cannulated artery. 4. Measurements in a limited number of dogs indicated that the local axillary and mesenteric venous levels of AVP were similar when the hormone was infused systemically at a rate of 220 pg min−1 kg−1 or intra-arterially at a lower rate. 5. These findings suggest that the increase in resistance measured in the skeletal muscle, small intestine, colon and abdominal fat after systemic administration of small amounts of AVP results in large part from indirect mechanisms. Direct vasoconstrictor effects of AVP at these plasma concentrations appear limited to the skin, the pancreas and the compact bones.

scholarly journals Revealing intraosseous blood flow in the human tibia with ultrasound

2021 ◽  
Author(s):  
Sebastien Salles ◽  
Jami Shepherd ◽  
Hendrik J. Vos ◽  
Guillaume Renaud
Keyword(s):  
Blood Flow ◽  
Cortical Bone ◽  
Femoral Artery ◽  
Bone Growth ◽  
Critical Role ◽  
Blood Perfusion ◽  
Blood Velocity ◽  
Bone Disorders ◽  
Peak Blood

Intraosseous blood circulation is thought to have a critical role in bone growth and remodeling, fracture healing, and bone disorders. However, it is rarely considered in clinical practice due to the absence of a suitable non-invasive in vivo measurement technique. In this work, we assessed blood perfusion in tibial cortical bone simultaneously with blood flow in the superficial femoral artery with ultrasound imaging in 5 healthy volunteers. After suppression of stationary signal with Singular-Value-Decomposition, pulsatile blood flow in cortical bone tissue is revealed, following the heart rate measured in the femoral artery. Using a method combining transverse oscillations and phase-based motion estimation, two-dimensional vector flow was obtained in the cortex of the tibia. After spatial averaging over the cortex, the peak blood velocity along the long axis of the tibia was measured four times larger than the peak blood velocity across the bone cortex. This suggests that blood flow in central (Haversian) canals is larger than in perforating (Volkmann's) canals, as expected from the intracortical vascular organization in humans. The peak blood velocity indicates a flow from the endosteum to the periosteum and from the heart to the foot for all subjects. Because aging and the development of bone disorders are thought to modify the direction and velocity of intra-cortical blood flow, their quantification is crucial. This work reports for the first time an in vivo quantification of the direction and velocity of blood flow in human cortical bone.

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