Whole body and muscle respiratory capacity with dobutamine and hindlimb suspension

1991 ◽  
Vol 71 (6) ◽  
pp. 2419-2424 ◽  
Author(s):  
D. Desplanches ◽  
R. Favier ◽  
B. Sempore ◽  
H. Hoppeler
Keyword(s):  
Soleus Muscle ◽  
Metabolic Response ◽  
Volume Density ◽  
Hindlimb Suspension ◽  
Whole Body ◽  
Capillary Length ◽  
Muscle Weight ◽  
Cross Sectional ◽  
Beneficial Effects ◽  
Mitochondrial Volume

The effects of repeated injections of dobutamine, a synthetic catecholamine, were studied in control and tail-suspended rats to determine whether this drug could improve the metabolic response to unweighting. Dobutamine prevented the decrease in maximal oxygen uptake (VO2max) induced by hindlimb suspension. Furthermore, VO2max was 12% greater in dobutamine-treated animals than in saline-treated control animals. Soleus muscle weight and mean fiber cross-sectional area were decreased by 60 and 75%, respectively, in saline- and dobutamine-treated suspended rats. Total capillary length was unaffected by unweighting and increased 21% in all animals receiving dobutamine. The drug prevented the increase in total mitochondrial volume density (+30%) induced by unweighting but did not change total mitochondrial volume. Our results suggest that 1) dobutamine is useful to prevent the decrease of total aerobic capacity during hindlimb suspension, 2) dobutamine increases VO2max in control rats, and 3) total capillary length in soleus muscle is increased by the drug in all groups, although no beneficial effects on mitochondria can be detected.

Rat soleus muscle ultrastructure after hindlimb suspension

1990 ◽  
Vol 69 (2) ◽  
pp. 504-508 ◽  
Author(s):  
D. Desplanches ◽  
S. R. Kayar ◽  
B. Sempore ◽  
R. Flandrois ◽  
H. Hoppeler
Keyword(s):  
Soleus Muscle ◽  
Capillary Density ◽  
Volume Density ◽  
Hindlimb Suspension ◽  
Tail Suspension ◽  
Cross Sectional ◽  
Muscle Ultrastructure ◽  
Rat Soleus Muscle ◽  
Mitochondrial Volume ◽  
Mitochondrial Volume Density

The aim of the present investigation was to determine, by quantitative electron microscopy, the effects of a 5-wk tail-suspension period on rat soleus muscle ultrastructure. A marked decline (-60%) in muscle mass occurred. The mean fiber cross-sectional area decreased to a greater extent (-75%) than the capillary-to-fiber ratio (-37%), leading to a higher capillary density (+148%) after hypokinesia. The total mitochondrial volume density remained unchanged, whereas the volume density of myofibrils was slightly but significantly reduced (-6%). A shift from subsarcolemmal to interfibrillar mitochondria occurred. Interfibrillar mitochondrial volume density was highest near the fiber border and decreased toward the fiber center. An increase in volume density of satellite cells suggested muscle regenerative events. Soleus atrophy with tail suspension greatly decreases the muscular volume but leaves the ultrastructural composition of muscle fibers relatively unaffected.

Absence of heat shock transcription factor 1 retards the regrowth of atrophied soleus muscle in mice

2011 ◽  
Vol 111 (4) ◽  
pp. 1142-1149 ◽  
Author(s):  
Kazuyuki Yasuhara ◽  
Yoshitaka Ohno ◽  
Atsushi Kojima ◽  
Kenji Uehara ◽  
Moroe Beppu ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Stress Response ◽  
Heat Shock ◽  
Soleus Muscle ◽  
Heat Shock Transcription Factor ◽  
Hindlimb Suspension ◽  
Wild Type ◽  
Muscle Weight ◽  
Cross Sectional ◽  
Transcription Factor 1

Effects of heat shock transcription factor 1 (HSF1) gene on the regrowth of atrophied mouse soleus muscles were studied. Both HSF1-null and wild-type mice were subjected to continuous hindlimb suspension for 2 wk followed by 4 wk of ambulation recovery. There was no difference in the magnitude of suspension-related decrease of muscle weight, protein content, and the cross-sectional area of muscle fibers between both types of mice. However, the regrowth of atrophied soleus muscle in HSF1-null mice was slower compared with that in wild-type mice. Lower baseline expression level of HSP25, HSC70, and HSP72 were noted in soleus muscle of HSF1-null mice. Unloading-associated downregulation and reloading-associated upregulation of HSP25 and HSP72 mRNA were observed not only in wild-type mice but also in HSF1-null mice. Reloading-associated upregulation of HSP72 and HSP25 during the regrowth of atrophied muscle was observed in wild-type mice. Minor and delayed upregulation of HSP72 at mRNA and protein levels was also seen in HSF1-null mice. Significant upregulations of HSF2 and HSF4 were observed immediately after the suspension in HSF1-null mice, but not in wild-type mice. Therefore, HSP72 expression in soleus muscle might be regulated by the posttranscriptional level, but not by the stress response. Evidence from this study suggested that the upregulation of HSPs induced by HSF1-associated stress response might play, in part, important roles in the mechanical loading (stress)-associated regrowth of skeletal muscle.

Geometry of blood-tissue exchange in bat flight muscle compared with bat hindlimb and rat soleus muscle

1992 ◽  
Vol 262 (6) ◽  
pp. R955-R965 ◽  
Author(s):  
O. Mathieu-Costello ◽  
J. M. Szewczak ◽  
R. B. Logemann ◽  
P. J. Agey
Keyword(s):  
Soleus Muscle ◽  
Sarcomere Length ◽  
Flight Muscle ◽  
Fiber Surface ◽  
Capillary Length ◽  
Fiber Volume ◽  
Cross Sectional ◽  
Fiber Size ◽  
Rat Soleus Muscle ◽  
Mitochondrial Volume

We investigated the relationship between capillary-to-fiber geometry and muscle aerobic capacity by comparing the bat flight muscle (pectoralis muscle), i.e., an ultimate case of extreme O2 demand in a mammalian skeletal muscle, with bat hindlimb and rat soleus muscles. At a given sarcomere length (2.1 microns), fiber cross-sectional area was considerably smaller in bat muscles (pectoralis 318 +/- 10 microns 2, hindlimb 447 +/- 35 microns 2) than in rat soleus muscle (2,027 +/- 125 microns 2). Capillary number per fiber cross-sectional area was much greater in bat pectoralis (6,394 +/- 380/mm2) than in bat hindlimb and rat soleus muscle (2,865 +/- 238 and 1,301 +/- 129/mm2, respectively; all values normalized to 2.1-microns sarcomere length). At the same sarcomere length (2.1 microns), the degree of tortuosity and branching of capillaries were significantly greater in bat pectoralis than in bat hindlimb and rat soleus muscle. In bat flight muscle, capillary length per fiber volume was very high (9,025 +/- 342/mm2). It was 2.2- and 5.4-fold larger than in bat hindlimb and rat soleus, respectively. Mitochondria occupied 35.3 +/- 1.2, 16.5 +/- 1.3, and 6.1 +/- 0.9% of the muscle fiber volume in bat pectoralis, hindlimb, and rat soleus muscles, respectively. There was a strong correlation between capillary length (as well as capillary surface) per fiber volume and mitochondrial volume density in all muscles. Considering capillary supply and mitochondrial volume on an individual fiber basis, we found that 1) the number of capillaries around a fiber was linearly related to mitochondrial volume per micron length of fiber in the muscles but that 2) capillary surface per fiber surface, at given mitochondrial volume per micron length of fiber, was about twice as large in bat pectoralis as in rat soleus muscle, whereas in bat hindlimb it was intermediate between that in bat pectoralis and that in rat soleus muscle. This was due to the differences in fiber size (rat soleus greater than bat muscles) and capillary-to-fiber ratio (bat pectoralis greater than hindlimb) between the muscles. It is notable that in the bat, the substantially greater O2 transfer capacity of the flight muscle compared with hindlimb was achieved by increasing the size of the capillary-to-fiber interface, i.e., capillary-to-fiber surface, via an increase in capillary number rather than by substantially reducing fiber size.

Capillary–fiber geometrical relationships in tuna red muscle

1992 ◽  
Vol 70 (6) ◽  
pp. 1218-1229 ◽  
Author(s):  
Odile Mathieu-Costello ◽  
Peter J. Agey ◽  
Richard B. Logemann ◽  
Richard W. Brill ◽  
Peter W. Hochachka
Keyword(s):  
Fiber Surface ◽  
Fish Muscle ◽  
Volume Density ◽  
Capillary Length ◽  
Fiber Volume ◽  
Cross Sectional ◽  
Red Muscle ◽  
Rat Soleus Muscle ◽  
Mitochondrial Volume ◽  
Mitochondrial Volume Density

The aim of this study was to examine the size and geometry of the capillary network in tuna red muscle, one of the most aerobic muscles in fish. Deep red muscle of 1.5- to 2-kg skipjack tuna, Katsuwonus pelamis, was perfusion fixed in situ, processed for electron microscopy, and analyzed by morphometry. Fiber cross-sectional area was 560 ± 30 (SE) μm2 in the samples. Capillary length per fiber volume was 4143 ± 242 (SE) mm−2 and mitochondrial volume density 28.5 ± 1.0 (SE) %. Indexes of capillarity such as average number of capillaries around a fiber, capillary length and surface per fiber volume, and capillary surface per fiber surface were high for a fish muscle. In fact, the size of the capillary–fiber interface (i.e., capillary to fiber surface) at a given mitochondrial volume per fiber was not significantly different in tuna red muscle compared with rat soleus muscle. However, calculation of mitochondrial respiratory rates in tuna red muscle yielded a substantially lower value (approximately 1/20th) compared with muscles of mammals. Besides the possible effect of differences in operating temperatures and (or) mitochondrial function(s) in fish compared with mammals, this suggests that the large capillary–fiber interface in tuna may be related to functions other than oxygen delivery per se, such as substrate and (or) heat transfer between capillaries and muscle fiber.

Fiber capillarization relative to mitochondrial volume in diaphragm of shrew

2002 ◽  
Vol 93 (1) ◽  
pp. 346-353 ◽  
Author(s):  
O. Mathieu-Costello ◽  
S. Morales ◽  
J. Savolainen ◽  
M. Vornanen
Keyword(s):  
Body Mass ◽  
Fiber Surface ◽  
Volume Density ◽  
Capillary Length ◽  
Fiber Volume ◽  
Hindlimb Muscle ◽  
Mitochondrial Volume ◽  
Flight Muscles ◽  
Mitochondrial Volume Density ◽  
Sorex Minutus

The objective was to examine fiber capillarization in relation to fiber mitochondrial volume in the highly aerobic diaphragm of the shrew, the smallest mammal. The diaphragms of four common shrews [ Sorex araneus; body mass, 8.2 ± 1.3 (SE) g] and four lesser shrews ( Sorex minutus, 2.6 ± 0.1 g) were perfusion fixed in situ, processed for electron microscopy, and analyzed by morphometry. Capillary length per fiber volume was extremely high, at values of 8,008 ± 1,054 and 12,332 ± 625 mm−2 in S. araneus and S. minutus, respectively ( P= 0.012), with no difference in capillary geometry between the two species. Fiber mitochondrial volume density was 28.5 ± 2.3% ( S. araneus) and 36.5 ± 1.4% ( S. minutus; P = 0.025), yielding capillary length per milliliter mitochondria values ( S. araneus, 27.8 ± 1.5 km; S. minutus, 33.9 ± 2.2 km; P = 0.06) as high as in the flight muscle of the hummingbird and small bats. The size of the capillary-fiber interface (i.e., capillary surface per fiber surface ratio) per fiber mitochondrial volume in shrew diaphragm was also as high as in bird and bat flight muscles, and it was about two times greater than in rat hindlimb muscle. Thus, whereas fiber capillary and mitochondrial volume densities decreased with increased body mass in S. araneus compared with S. minutusSoricinae shrews, fiber capillarization per milliliter mitochondria in both species was much higher than previously reported for shrew diaphragm, and it matched that of the intensely aerobic flight muscles of birds and mammals.

Transcriptional reprogramming and ultrastructure during atrophy and recovery of mouse soleus muscle

2004 ◽  
Vol 20 (1) ◽  
pp. 97-107 ◽  
Author(s):  
Christoph Däpp ◽  
Silvia Schmutz ◽  
Hans Hoppeler ◽  
Martin Flück
Keyword(s):  
Soleus Muscle ◽  
Glycolytic Enzyme ◽  
Hindlimb Suspension ◽  
Published Data ◽  
Capillary Length ◽  
Muscle Plasticity ◽  
Fiber Area ◽  
Transcriptional Reprogramming ◽  
Myogenic Factors ◽  
Species Specific

This study investigated the use of the hindlimb suspension (HS) and reloading model of mice for the mapping of ultrastructural and gene expressional alterations underlying load-dependent muscular adaptations. Mice were hindlimb suspended for 7 days or kept as controls ( n = 12). Soleus muscles were harvested after HS (HS7, n = 23) or after resuming ambulatory cage activity (reloading) for either 1 day (R1, n = 13) or 7 days (R7, n = 9). Using electron microscopy, a reduction in mean fiber area (−37%) and in capillary-to-fiber ratio (from 1.83 to 1.42) was found for HS7. Subsequent reloading caused an increase in interstitial cells (+96%) and in total capillary length (+57%), whereas mean fiber area and capillary-to-fiber ratio did not significantly change compared with HS. Total RNA in the soleus muscle was altered with both HS (−63%) and reloading (+108% in R7 compared with control). This is seen as an important adaptive mechanism. Gene expression alterations were assessed by a muscle-specific low-density cDNA microarray. The transcriptional adjustments indicate an early increase of myogenic factors during reloading together with an overshoot of contractile (MyHC I and IIa) and metabolic (glycolytic and oxidative) mRNA amounts and suggest mechano-sensitivity of factors keeping the sarcomeres in register (desmin, titin, integrin-β1). Important differences to published data from former rat studies were found with the mouse HS model for contractile and glycolytic enzyme expression. These species-specific differences need to be considered when transgenic mice are used for the elucidation of monogenetic factors in mechano-dependent muscle plasticity.

Capillary growth and geometry during long-term hypertension and myocardial hypertrophy in dogs

1991 ◽  
Vol 261 (4) ◽  
pp. H1011-H1018 ◽  
Author(s):  
R. J. Tomanek ◽  
T. J. Wessel ◽  
D. G. Harrison
Keyword(s):  
Volume Density ◽  
Left Ventricular ◽  
Capillary Length ◽  
Cross Sectional ◽  
Orientation Degree ◽  
Capillary Growth ◽  
Lv Mass ◽  
Intercapillary Distance ◽  
Capillary Bed

Angiogenic response of the myocardial capillary bed to long-term (7 mo) renovascular hypertension (one-kidney, one-clip) was assessed in eight mongrel dogs and compared with seven control dogs. Image analyses of histological sections from four transmural specimen sites of left ventricular (LV) free wall were performed. While mean cross-sectional cardiocyte area increased in all transmural layers (epi-endo) in dogs with LV hypertrophy (LVH), the greatest increases occurred in the inner layers. Although capillary length density was significantly lower in two of the four transmural regions of LVH dogs, these decrements were much less than the lateral expansion of cardiocytes as indicated by cross-sectional areas. Calculations of total capillary length indicate that approximately one-fifth of the capillary bed in LVH dogs was formed during the 7-mo period of hypertension in hypertrophied hearts. Capillary volume and surface densities in LVH dogs decreased to a greater extent due to a larger population of capillaries with lumen diameters less than 4 microns. Capillary volume density in LVH dogs was remarkably similar across the wall despite large transmural differences in cardiocyte hypertrophy. LVH did not alter the log SD of capillary domains, a measure of the heterogeneity of spacing, or capillary orientation (degree or anisotropy). These data support several important conclusions regarding long-term hypertension-induced LVH in dogs. First, although capillary growth does not fully compensate for the increase in LV mass, a myriad of new capillaries are formed as indicated by a substantial increase in total capillary length. This growth minimizes the increase in intercapillary distance characteristic of LVH.(ABSTRACT TRUNCATED AT 250 WORDS)

Compensated coronary microvascular growth in senescent rats with thyroxine-induced cardiac hypertrophy

1995 ◽  
Vol 268 (1) ◽  
pp. H419-H425 ◽  
Author(s):  
R. J. Tomanek ◽  
P. M. Connell ◽  
C. A. Butters ◽  
R. J. Torry
Keyword(s):  
Young Adult ◽  
Cardiac Hypertrophy ◽  
Coronary Vessels ◽  
Weight Ratio ◽  
Volume Density ◽  
Heart Weight ◽  
Age Group ◽  
Capillary Length ◽  
Adult Rats ◽  
Cross Sectional

We tested the hypothesis that coronary angiogenesis in response to chronic thyroxine (T4) treatment is not limited by age. Male Fischer 344 rats aged either 8 (young adult) or 24 (senescent) mo were studied after receiving either L-thyroxine (0.2 mg/kg sc) or vehicle for 2 mo. Heart weight-to-body weight ratio, compared with age-matched controls, increased by 47 and 44% in 8- and 24-mo T4 groups, respectively. Maximal myocardial perfusion per unit mass, measured in diastole-arrested, maximally dilated, isolated hearts, was similar in T4 rats and their age group controls; however, flow tended to be lower in senescent than in young adult rats. Thus the cross-sectional area of the coronary vessels grew in proportion to the increase in cardiac mass. Morphometric analyses, based on image analysis, showed that capillary length density was slightly lower in the midmyocardium but not the epimyocardium of the 24-mo T4 group compared with their age group controls. However, volume density, surface density, and intercapillary distance were not influenced by T4 treatment and the presence of cardiac hypertrophy. We conclude that in this model of cardiac hypertrophy 1) coronary vessel growth parallels the increase in ventricular mass, 2) capillaries grow by proliferation and an increase in diameter, and 3) vascular growth is not notably compromised during senescence.

Running during recovery from hindlimb suspension induces transient muscle injury

1990 ◽  
Vol 68 (2) ◽  
pp. 533-539 ◽  
Author(s):  
C. E. Kasper ◽  
T. P. White ◽  
L. C. Maxwell
Keyword(s):  
Soleus Muscle ◽  
Recovery Period ◽  
Morphological Characteristics ◽  
Cross Sectional Area ◽  
Hindlimb Suspension ◽  
Type I ◽  
Sectional Area ◽  
Cross Sectional ◽  
Female Wistar Rats ◽  
Type I Fibers

The objectives were to study morphological adaptations of soleus muscle to decreased loading induced by hindlimb suspension and the effect of run training during the subsequent recovery period. Adult female Wistar rats were kept for 28 days with hindlimbs suspended. For the next 28 days, rats were assigned to a cage-sedentary or daily running group. Compared with control soleus muscles, 28 days of hindlimb suspension reduced the mass and fiber cross-sectional area to 58 and 53% of control values, respectively, and decreased type I fibers from 92 +/- 2 to 81 +/- 2%. During recovery, clusters of damaged fibers were observed in the soleus muscle, and this observation was more pronounced in trained animals. Type IIc fibers appeared transiently during recovery, and their presence was exacerbated with training, as IIc fibers increased to approximately 20% of the total by day 14 of recovery and were no longer evident at day 28. Although muscle wet mass does not differ as a result of mode of recovery at day 14, training transiently decreased the overall fiber area compared with sedentary recovery at this point. By day 28 of recovery the morphological characteristics of soleus muscle in the trained group did not differ from control muscle, whereas in the sedentary group muscle mass and overall fiber cross-sectional area were approximately 14% less than control values.

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