Changes in the capillarity of skeletal muscle in the growing rat

Ripoll, E.; Sillau, A. H.; Banchero, Natalio

doi:10.1007/bf00582151

Cited by 82 publications

(54 citation statements)

References 19 publications

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“…This trend continues during progression from the juvenile to mature stages, in which muscle mass undergoes an additional 50% increase (19) with no further increase in arcade bridge volume flow (Table 2). This finding is consistent with various studies documenting a progressive decrease in tissue metabolic demand as growth continues (28,30).…”

Section: Discussionsupporting

confidence: 93%

Growth-related changes in the influence of nitric oxide on arteriolar tone

Linderman

Boegehold

1999

American Journal of Physiology-Heart and Circulatory Physiology

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Linderman, J. R., and M. A. Boegehold. Growth-related changes in the influence of nitric oxide on arteriolar tone. Am. J. Physiol. 277 (Heart Circ. Physiol. 46): H1570-H1578, 1999.-This study was designed to determine whether juvenile growth is accompanied by changes in the local influence of nitric oxide (NO) or prostaglandins on arteriolar tone. In vivo microscopy was used to study proximal arterioles in the spinotrapezius muscle of rats 4-5 wk (weanling), 7-8 wk (juvenile), and 11-12 wk (mature) of age. From 4 to 12 wk of age, arterioles underwent an increase in resting diameter (from 31 Ϯ 2 to 49 Ϯ 2 µm) and volume flow (from 7 Ϯ 1 to 10 Ϯ 1 nl/s) but a decrease in resting wall shear rate (from 1,901 Ϯ 150 to 748 Ϯ 50 s Ϫ1 ). NO synthase inhibition with N G -monomethyl-L-arginine (L-NMMA) had no effect on arteriolar diameters in weanling rats but reduced diameters by 14 Ϯ 4% in juvenile rats and by 13 Ϯ 4% in mature rats. Cyclooxygenase inhibition with meclofenamate reduced arteriolar diameters by a similar amount (13 Ϯ 4 to 18 Ϯ 3%) in all age groups. There were no age-related differences in arteriolar responsiveness to locally applied sodium nitroprusside or prostaglandin E 2 . Arteriolar responsiveness to ACh was also similar in all groups, but the L-NMMA-sensitive portion of this response was smaller in mature rats than in weanling rats. Elevation of flow-related shear stress caused arteriolar dilation in juvenile rats but not in weanling rats. These findings suggest that arteriolar smooth muscle responsiveness to NO or prostaglandins does not change during juvenile growth and that basally released vasodilator prostaglandins exert a constant influence on arteriolar tone throughout this period. Basal NO activity also modulates arteriolar tone in juvenile and mature rats but not in weanling rats. In contrast, agonist-stimulated NO release is prominent in weanling and juvenile rats but somewhat decreased in mature rats, where cyclooxygenase products also contribute to ACh induced dilation.

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Section: Discussionsupporting

confidence: 93%

Growth-related changes in the influence of nitric oxide on arteriolar tone

Linderman

Boegehold

1999

American Journal of Physiology-Heart and Circulatory Physiology

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“…Fig. 3 is the hyperbolic fit that was reported by Ripoll et al (1979). This line cuts across the points of our control animals while the points that correspond to all the T3-treated animals show greater values ofc .d.…”

Section: Resultsmentioning

confidence: 75%

“…while C/F increases linearly with f.c.s.a. (Ripoll et al 1979;Aquin, Sillau, Lechner & Banchero, 1980). Fig.…”

Section: Resultsmentioning

confidence: 98%

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The effect of hyperthyroidism on capillarity and oxidative capacity in rat soleus and gastrocnemius muscles.

Capó¹,

Sillau²

1983

The Journal of Physiology

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SUMMARY1. Muscle fibre composition and capillarity were evaluated in frozen sections stained for myosin ATPase of the soleus and the white area of the medial head of the gastrocnemius of rats made hyperthyroid by injections of triiodothyronine (300-400 ,ug/kg body weight, every other day) for 2, 3 and 4 weeks.2. 02 consumption of homogenates of these muscles in the presence of excess inorganic phosphate (Pi) and ADP with pyruvate and malate as substrates was also measured. 3. Increased oxidative capacity was observed in the soleus homogenates of hyperthyroid animals after 2 weeks of treatment while no changes were observed in the oxidative capacity of the homogenates of the white area of the medial head of the gastrocnemius, even after 4 weeks of treatment.4. Hyperthyroid animals showed a greater capillarity than controls in both muscles. In the soleus this was evident after 2 weeks of treatment while in the white area of the medial head of the gastrocnemius, it was evident only after 4 weeks of treatment.5. Fibre composition was affected in the soleus after 4 weeks of treatment. In control animals two fibre types were present in the soleus: slow-twitch oxidative fibres (s.o. or type I fibres) with a high ATPase activity after acid pre-incubation and fast-twitch glycolytic oxidative fibres (f.o.g. or type IIa fibres) with a low ATPase activity after acid pre-incubation. In the soleus of the hyperthyroid animals, a third fibre type with intermediate ATPase activity after acid pre-incubation was also present. This most probably represents a change in the type of myosin being synthesized by some fibres. No changes in fibre composition were observed in the white area of medial head ofthe gastrocnemius which was made up of only fast-twitch glycolytic fibres (f.g. or type IIb fibres).6. The changes in oxidative capacity and capillarity in the soleus preceded and did not seem to be related to the changes in the type of myosin being synthesized.7. The increased capillarity found in the white area of the medial head of the gastrocnemius of the hyperthyroid animals, in the absence of an increase in the * To whom reprint requests should be addressed.

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“…We choose to use 9-month-old Fischer 344ϫ Brown Norway rats because rats have had their largest growth rate before 6 months of age. The use of these rats would prevent any bias that may occur as a consequence of normal muscle growth and of accompanying shifts in fiber type composition and capillarization that occur especially during the first 10 weeks of normal growth and development [14,15]. The institutional animal use and care committee approved all the experiments described below.…”

Section: Animalsmentioning

confidence: 99%

Vascular Endothelial Growth Factor, Capillarization, and Function of the Rat Plantaris Muscle at the Onset of Hypertrophy.

Degens

Moore²,

Alway³

2003

JJP

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Skeletal muscle has a great ability to respond to altered functional demands. This response includes, among other adaptations, changes in muscle size, fiber-type composition, and capillary supply, resulting in altered contractile properties and fatigue resistance [1]. The response to the increased functional demand imposed on a muscle by the elimination of agonist muscles involves compensatory hypertrophy. This hypertrophy is accompanied by an increase in the number of type I fibers and capillary proliferation [2][3][4][5][6][7]. Concomitantly, the force generating capacity and fatigue resistance of the hypertrophied muscle increases [3,8].The absence of significant hypertrophy during at least the first week after the functional elimination of synergists [4,9] suggests that the muscle needs time to recover from the early damage [10] before the onset of real growth. Furthermore, the presence of transi- Japanese Journal of Physiology, 53, 181-191, 2003 Key words: capillary, fatigue, specific tension, myosin heavy chain, muscle.Abstract: Capillary proliferation occurs during compensatory hypertrophy. We investigated whether the expression of vascular endothelial growth factor (VEGF) is elevated at the onset of hypertrophy when capillary proliferation is minimal, and whether muscle damage as assessed by muscle force deficits, may occur at the onset of hypertrophy. To investigate this, we induced in 9-month-old rats, under isoflurane anesthesia, hypertrophy of the left plantaris muscle by denervation of the gastrocnemius and soleus muscles. Capillarization was investigated in both the deep (oxidative) and the superficial (glycolytic) regions of the plantaris muscle. After 2 weeks, muscle mass had increased by 16% (pϽ0.01), which was not accompanied by increases in fiber size. The maximal tetanic force (P 0 ) and specific ten-) and twitch characteristics were unaltered, and fatigue resistance of the overloaded muscle was improved (pϽ0.05). However, the myosin heavy chain composition was unaltered. Capillary proliferation was not yet evident, but VEGF mRNA and protein levels were elevated 1.5-and 8-fold, respectively (pϽ0.05). We concluded that the normal specific tension and the elevated VEGF expression after 2 weeks of overload indicate (1) an absence of or minimal muscle damage at this early time point, and (2) that elevated VEGF expression precedes and is involved in capillary proliferation that occurs during the later stages of compensatory hypertrophy.

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Changes in the capillarity of skeletal muscle in the growing rat

Cited by 82 publications

References 19 publications

Growth-related changes in the influence of nitric oxide on arteriolar tone

Growth-related changes in the influence of nitric oxide on arteriolar tone

The effect of hyperthyroidism on capillarity and oxidative capacity in rat soleus and gastrocnemius muscles.

Vascular Endothelial Growth Factor, Capillarization, and Function of the Rat Plantaris Muscle at the Onset of Hypertrophy.

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