Capillary supply of skeletal muscles from acclimatized white-footed mice Peromyscus

1981 ◽  
Vol 241 (5) ◽  
pp. R357-R361
Author(s):  
S. J. Wickler
Keyword(s):  
Skeletal Muscle ◽  
Heat Production ◽  
Skeletal Muscles ◽  
Capillary Density ◽  
Area Index ◽  
Fiber Area ◽  
Hindlimb Muscles ◽  
The Mean ◽  
Thermogenic Capacity ◽  
Muscle Capillaries

Winter-acclimatized white-footed mice (Peromyscus leucopus) can increase their aerobic heat production under cold stress by 70%. The possibility that changes in microvascular supply might account, in part, for some of this increased thermogenic capacity was examined in one of the primary thermogenic tissues, skeletal muscle. Capillaries were stained histochemically in four hindlimb muscles of freshly captured Peromyscus in summer and winter. Capillary density, mean fiber area, and mean capillaries in contact per muscle fiber were obtained from the soleus, plantaris, gastrocnemius, and semitendinosus. If results from all individual muscles are combined, mean fiber area is significantly smaller (8%) and mean capillary density is significantly greater (40%) in winter muscles. The mean number of capillaries in contact is not different, but the mean ratio of capillaries in contact per mean fiber area (index of potential perfusion) is significantly greater (25%) in winter muscles.

Lower capillary density but no difference in VEGF expression in obese vs. lean young skeletal muscle in humans

2005 ◽  
Vol 98 (1) ◽  
pp. 315-321 ◽  
Author(s):  
Timothy P. Gavin ◽  
Howard W. Stallings ◽  
Kevin A. Zwetsloot ◽  
Lenna M. Westerkamp ◽  
Nicholas A. Ryan ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Insulin Sensitivity ◽  
Linear Regression ◽  
Oxygen Uptake ◽  
Maximal Oxygen Uptake ◽  
Capillary Density ◽  
Area Ratio ◽  
Receptor Expression ◽  
Vegf Receptor ◽  
Fiber Area

Obesity is associated with lower skeletal muscle capillarization and lower insulin sensitivity. Vascular endothelial growth factor (VEGF) is important for the maintenance of the skeletal muscle capillaries. To investigate whether VEGF and VEGF receptor [kinase insert domain-containing receptor (KDR) and Flt-1] expression are lower with obesity, vastus lateralis muscle biopsies were obtained from eight obese and eight lean young sedentary men before and 2 h after a 1-h submaximal aerobic exercise bout for the measurement of VEGF, KDR, Flt-1, and skeletal muscle fiber and capillary characteristics. There were no differences in VEGF or VEGF receptor mRNA at rest between lean and obese muscle. Exercise increased VEGF (10-fold), KDR (3-fold), and Flt-1 (5-fold) mRNA independent of group. There were no differences in VEGF, KDR, or Flt-1 protein between groups. Compared with lean skeletal muscle, the number of capillary contacts per fiber was the same, but lower capillary density (CD), greater muscle cross sectional area, and lower capillary-to-fiber area ratio were observed in both type I and II fibers in obese muscle. Multiple linear regression revealed that 49% of the variance in insulin sensitivity (homeostasis model assessment) could be explained by percentage of body fat (35%) and maximal oxygen uptake per kilogram of fat-free mass (14%). Linear regression revealed significant relationships between maximal oxygen uptake and both CD and capillary-to-fiber perimeter exchange. Although differences may exist in CD and capillary-to-fiber area ratio between lean and obese skeletal muscle, the present results provide evidence that VEGF and VEGF receptor expression are not different between lean and obese muscle.

Insulin binding to individual rat skeletal muscles

1990 ◽  
Vol 259 (4) ◽  
pp. E517-E523 ◽  
Author(s):  
D. J. Koerker ◽  
I. R. Sweet ◽  
D. G. Baskin
Keyword(s):  
Skeletal Muscle ◽  
Insulin Sensitivity ◽  
Binding Sites ◽  
Skeletal Muscles ◽  
Dissociation Constants ◽  
Binding Capacity ◽  
Fiber Type ◽  
Insulin Binding ◽  
Computer Assisted ◽  
Hindlimb Muscles

Studies of insulin binding to skeletal muscle, performed using sarcolemmal membrane preparations or whole muscle incubations of mixed muscle or typical red (soleus, psoas) or white [extensor digitorum longus (EDL), gastrocnemius] muscle, have suggested that red muscle binds more insulin than white muscle. We have evaluated this hypothesis using cryostat sections of unfixed tissue to measure insulin binding in a broad range of skeletal muscles; many were of similar fiber-type profiles. Insulin binding per square millimeter of skeletal muscle slice was measured by autoradiography and computer-assisted densitometry. We found a 4.5-fold range in specific insulin tracer binding, with heart and predominantly slow-twitch oxidative muscles (SO) at the high end and the predominantly fast-twitch glycolytic (FG) muscles at the low end of the range. This pattern reflects insulin sensitivity. Evaluation of displacement curves for insulin binding yielded linear Scatchard plots. The dissociation constants varied over a ninefold range (0.26-2.06 nM). Binding capacity varied from 12.2 to 82.7 fmol/mm2. Neither binding parameter was correlated with fiber type or insulin sensitivity; e.g., among three muscles of similar fiber-type profile, the EDL had high numbers of low-affinity binding sites, whereas the quadriceps had low numbers of high-affinity sites. In summary, considerable heterogeneity in insulin binding was found among hindlimb muscles of the rat, which can be attributed to heterogeneity in binding affinities and the numbers of binding sites. It can be concluded that a given fiber type is not uniquely associated with a set of insulin binding parameters that result in high or low binding.

Oxidative capacity, blood flow, and capillarity of skeletal muscles

1980 ◽  
Vol 49 (4) ◽  
pp. 627-633 ◽  
Author(s):  
L. C. Maxwell ◽  
T. P. White ◽  
J. A. Faulkner
Keyword(s):  
Blood Flow ◽  
Skeletal Muscles ◽  
Muscle Blood Flow ◽  
Muscle Fibers ◽  
Capillary Density ◽  
Oxidative Capacity ◽  
Histochemical Demonstration ◽  
Capillary Endothelium ◽  
Fiber Types ◽  
Fiber Area

Our purpose was to test the hypothesis that the capillarity of mammalian skeletal muscles is correlated with the oxidate capacity of muscle fibers, or with the capacity for maximum blood flow. Capillarity of skeletal muscles from several species was determined using histochemical demonstration of phosphatase activity of capillary endothelium. Serial sections were incubated for succinate dehydrogenase activity as an indicator of muscle fiber oxidative capacity, and for myofibrillar ATPase activity. three types of muscle fibers were identified. Fiber area was determined by planimetry of projected cross sections. Succinate oxidase activity of whole homogenates was determined by differential respirometry. Muscle blood flow was determined experimentally or data were obtained from the literature. No consistent relation was observed for the different fiber types in the number of adjacent capillaries. Capillary density was negatively correlated with mean fiber area. Among adult animals of several species, skeletal muscles representing a 17-fold range of oxidative capacity demonstrated no relation between capillarity and oxidative capacity or muscle blood flow at maximum oxygen uptake. We find no support for relations between oxidative capacity of muscle blood flow and the capillarity of whole muscle or individual fibers and reject the hypothesis.

Induction and maintenance of increased VEGF protein by chronic motor nerve stimulation in skeletal muscle

1998 ◽  
Vol 274 (3) ◽  
pp. H860-H867 ◽  
Author(s):  
Brian H. Annex ◽  
Carol E. Torgan ◽  
Pengnian Lin ◽  
Doris A. Taylor ◽  
Michael A. Thompson ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Nerve Stimulation ◽  
Skeletal Muscles ◽  
Motor Nerve ◽  
Capillary Density ◽  
Endothelial Cell Proliferation ◽  
Vascular Density ◽  
Oxidative Phenotype ◽  
Vegf Protein

Vascular endothelial growth factor (VEGF) causes endothelial cell proliferation in vitro and angiogenesis in vivo. Glycolytic skeletal muscles have a lower capillary density than oxidative muscles but can increase their capillary density and convert to a more oxidative phenotype when subject to chronic motor nerve stimulation (CMNS). We used Western analysis and immunohistochemical techniques to examine VEGF protein in a rabbit CMNS model of glycolytic skeletal muscle and in muscles with innate glycolytic versus oxidative phenotypes. VEGF protein per gram of total protein was increased in stimulated vs. control muscles 2.9 ± 1.0, 3.6 ± 1.3, 3.1 ± 0.5, 4.4 ± 1.6, and 2.7 ± 0.3 times after 3 ( n = 4), 5 ( n = 2), 10 ( n = 3), 21 ( n = 3), and 56 ( n = 2) days, respectively. VEGF protein was increased 3.1 ± 0.5 times ( P < 0.005) before (3, 5, and 10 days) and remained elevated 3.7 ± 1.0 times ( P < 0.05) after (21 and 56 days) the transition to an oxidative phenotype. By immunohistochemistry, VEGF protein was found primarily in the matrix between stimulated muscle fibers but not in the myocytes. In addition, VEGF protein was consistently lower in innate glycolytic compared with oxidative muscles. These findings suggest that VEGF plays a role in the alteration and maintenance of vascular density in mammalian skeletal muscles.

CALORIC RESTRICTION ALTERS CAPILLARY DENSITY AND SKELETAL MUSCLE FIBER AREA WITH AGE IN B6C3F1 MICE.

1995 ◽  
Vol 27 (Supplement) ◽  
pp. S235
Author(s):  
N. Johnson ◽  
A. C. Cosmas ◽  
R. Bronson ◽  
R. Lipman ◽  
W. Ding ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Caloric Restriction ◽  
Muscle Fiber ◽  
Capillary Density ◽  
Skeletal Muscle Fiber ◽  
Fiber Area ◽  
B6c3f1 Mice

Profile of creatine kinase isoenzymes in skeletal muscles of marathon runners.

1984 ◽  
Vol 30 (3) ◽  
pp. 413-416 ◽  
Author(s):  
F S Apple ◽  
M A Rogers ◽  
W M Sherman ◽  
D L Costill ◽  
F C Hagerman ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Creatine Kinase ◽  
Skeletal Muscles ◽  
Gastrocnemius Muscle ◽  
Distance Runners ◽  
Long Distance ◽  
Marathon Runners ◽  
Isoenzyme Composition ◽  
The Mean ◽  
Muscle Biopsies

Abstract The proportion of creatine kinase (CK; EC 2.7.3.2) isoenzyme MB activity was increased in skeletal muscle biopsies obtained from five long-distance runners, both 2 h before (mean 7.7%, SD 2.4%) and 30 min after (mean 7.2%, SD 1.2%) a marathon race, as compared with that in biopsies from five nonrunners (controls less than or equal to 1.0%). Further, mitochondrial CK and CK-BB isoenzymes were present in homogenates of the runners' skeletal muscle samples but not in those of the nonrunners. However, there were no substantial differences in the mean total CK activities per gram (wet wt.) of muscle tissue among premarathon samples, postmarathon samples, and nonrunners' samples (3148, 3365, and 3049 U/g, respectively). We conclude that the metabolically active gastrocnemius muscle of long-distance runners is qualitatively similar to the heart muscle in its CK isoenzyme composition.

Phenotype of capillaries in skeletal muscle of nNOS-knockout mice

2013 ◽  
Vol 304 (12) ◽  
pp. R1175-R1182 ◽  
Author(s):  
Oliver Baum ◽  
Max Vieregge ◽  
Pascale Koch ◽  
Safak Gül ◽  
Sabine Hahn ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Growth Factor ◽  
Hypoxia Inducible Factor ◽  
Capillary Density ◽  
Vegf Receptor ◽  
Mrna Levels ◽  
Mean Velocity ◽  
Cross Sectional ◽  
The Mean ◽  
Edl Muscle

Because neuronal nitric oxide synthase (nNOS) has a well-known impact on arteriolar blood flow in skeletal muscle, we compared the ultrastructure and the hemodynamics of/in the ensuing capillaries in the extensor digitorum longus (EDL) muscle of male nNOS-knockout (KO) mice and wild-type (WT) littermates. The capillary-to-fiber (C/F) ratio (−9.1%) was lower ( P ≤ 0.05) in the nNOS-KO mice than in the WT mice, whereas the mean cross-sectional fiber area (−7.8%) and the capillary density (−3.1%) varied only nonsignificantly ( P > 0.05). Morphometrical estimation of the area occupied by the capillaries as well as the volume and surface densities of the subcellular compartments differed nonsignificantly ( P > 0.05) between the two strains. Intravital microscopy revealed neither the capillary diameter (+3% in nNOS-KO mice vs. WT mice) nor the mean velocity of red blood cells in EDL muscle (+25% in nNOS-KO mice vs. WT mice) to significantly vary ( P > 0.05) between the two strains. The calculated shear stress in the capillaries was likewise nonsignificantly different (3.8 ± 2.2 dyn/cm2 in nNOS-KO mice and 2.1 ± 2.2 dyn/cm2 in WT mice; P > 0.05). The mRNA levels of vascular endothelial growth factor (VEGF)-A were lower in the EDL muscle of nNOS-KO mice than in the WT littermates (−37%; P ≤ 0.05), whereas mRNA levels of VEGF receptor-2 (VEGFR-2) (−11%), hypoxia inducible factor-1α (+9%), fibroblast growth factor-2 (−14%), and thrombospondin-1 (−10%) differed nonsignificantly ( P > 0.05). Our findings support the contention that VEGF-A mRNA expression and C/F-ratio but not the ultrastructure or the hemodynamics of/in capillaries in skeletal muscle at basal conditions depend on the expression of nNOS.

Relationship between performance at different exercise intensities and skeletal muscle characteristics

2011 ◽  
Vol 110 (6) ◽  
pp. 1555-1563 ◽  
Author(s):  
F. Marcello Iaia ◽  
Jorge Perez-Gomez ◽  
Martin Thomassen ◽  
Nikolai B. Nordsborg ◽  
Ylva Hellsten ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Exercise Performance ◽  
Capillary Density ◽  
Exercise Time ◽  
Physiological Variables ◽  
Subunit Expression ◽  
Performance Times ◽  
Fast Twitch ◽  
Large Distribution ◽  
Muscle Capillaries

The hypothesis investigated whether exercise performance over a broad range of intensities is determined by specific skeletal muscle characteristics. Seven subjects performed 8–10 exhaustive cycle trials at different workloads, ranging from 150 to 700 W (150 min to 20 s). No relationships between the performance times at high and low workloads were observed. A relationship ( P < 0.05) was noticed between the percentage of fast-twitch x fibers and the exercise time at 579 ± 21 W (∼30 s; r2 = 0.88). Capillary-to-fiber-ratio ( r2: 0.58–0.85) was related ( P < 0.05) to exercise time at work intensities ranging from 395 to 270 W (2.5–21 min). Capillary density was correlated ( r2 = 0.68; P < 0.05) with the net rate of plasma K+ accumulation during an ∼3-min bout and was estimated to explain 50–80% ( P < 0.05) of the total variance observed in exercise performances lasting ∼30 s to 3 min. The Na+-K+ pump β1-subunit expression was found to account for 13–34% ( P < 0.05) during exhaustive exercise of ∼1–4 min. In conclusion, exercise performance at different intensities is related to specific physiological variables. A large distribution of fast-twitch x fibers may play a role during very intense efforts, i.e., ∼30 s. Muscle capillaries and the Na+-K+ pump β1-subunit seem to be important determinants for performance during exhaustive high-intensity exercises lasting between 30 s and 4 min.

Endothelial NOS is main mediator for shear stress-dependent angiogenesis in skeletal muscle after prazosin administration

2004 ◽  
Vol 287 (5) ◽  
pp. H2300-H2308 ◽  
Author(s):  
Oliver Baum ◽  
Luis Da Silva-Azevedo ◽  
Gregor Willerding ◽  
Achim Wöckel ◽  
Gerit Planitzer ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Knockout Mice ◽  
Skeletal Muscles ◽  
Capillary Density ◽  
Enos Expression ◽  
Wall Shear ◽  
Stress Dependent ◽  
Endothelial Nitric Oxide

The increase of wall shear stress in capillaries by oral administration of the α1-adrenergic receptor antagonist prazosin induces angiogenesis in skeletal muscles. Because endothelial nitric oxide synthase (eNOS) is upregulated in response to elevated wall shear stress, we investigated the relevance of eNOS for prazosin-induced angiogenesis in skeletal muscles. Prazosin and/or the NOS inhibitor Nω-nitro-l-arginine methyl ester (l-NAME) were given to C57BL/6 wild-type mice and eNOS-knockout mice for 14 days. The capillary-to-fiber (C/F) ratio and capillary density (CD; no. of capillaries/mm2) were determined in frozen sections from extensor digitorum longus (EDL) muscles of these mice. Immunoblotting was performed to quantify eNOS expression in endothelial cells isolated from skeletal muscles, whereas VEGF (after precipitation with heparin-agarose) and neuronal NOS (nNOS) concentrations were determined in EDL solubilizates. In EDL muscles of C57BL/6 mice treated for 14 days, the C/F ratio was 28% higher after prazosin administration and 11% higher after prazosin and l-NAME feeding, whereas the CD increased by 21 and 13%, respectively. The C/F ratio was highest after day 4 of prazosin treatment and decreased gradually to almost constant values after day 8. Prazosin administration led to elevation of eNOS expression. VEGF levels were lowest at day 4, whereas nNOS values decreased after day 8. In EDL muscles of eNOS-knockout mice, no significant changes in C/F ratio, CD, or VEGF and nNOS expression were observed in response to prazosin administration. Our data suggest that the presence of eNOS is essential for prazosin-induced angiogenesis in skeletal muscle, albeit other signaling molecules might partially compensate for or contribute to this angiogenic activity. Furthermore, subsequent remodeling of the capillary system accompanied by sequential downregulation of VEGF and nNOS in skeletal muscle fibers characterizes shear stress-dependent angiogenesis.

Capillary proliferative activity in myocardium and skeletal muscle of exercised rats

1977 ◽  
Vol 43 (2) ◽  
pp. 306-307 ◽  
Author(s):  
A. Ljungqvist ◽  
G. Unge
Keyword(s):  
Skeletal Muscle ◽  
Cardiac Hypertrophy ◽  
Experimental Model ◽  
Proliferative Activity ◽  
Skeletal Muscles ◽  
Capillary Blood ◽  
Hindlimb Muscles ◽  
Capillary Walls ◽  
Normal Controls

The capillary proliferative activity in heart and skeletal muscle was studied by autoradiography after in vivo injections of [3H]thymidine in swimming exercised rats. Swimming exercise led to hypertrophy of the myocardium and the muscle fibers of the fore- and hindlimbs. When compared with normal controls a highly significant increase in nuclear incorporation of [3H]thymidine was found in the cells of the myocardial capillary walls. No increased incorporation of [3H]thymidine was found in capillary wall cells of fore- and hindlimb muscles. The findings confirm previous observations of a significant neoformation of myocardial capillary blood vessels in swimming-induced cardiac hypertrophy, whereas any capillary neoformation in the hypertrophying skeletal muscles of this experimental model is insignificant.

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