The Extracellular Space in Red and White Muscles of the Rat

Kobayashi, Nobuya; Yonemura, K

doi:10.2170/jjphysiol.17.698

Cited by 27 publications

(11 citation statements)

References 8 publications

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“…5B) at 0% strain, 0.12 ± 0.01, was in agreement with extracellular inulin space (0.12 ± 0.01) found previously in rat soleus [27]. Imprecision in porosity measurements may arise from cross-sections taken perpendicular to the muscle body rather than to the myofibers, which have a 6° pennation angle to the muscle axis.…”

Section: Resultssupporting

confidence: 88%

Intramuscular drug transport under mechanical loading: Resonance between tissue function and uptake

Minisini

Edelman

2009

Journal of Controlled Release

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Dynamic architecture and motion in mechanically active target tissues can influence the pharmacokinetics of locally delivered agents. Drug transport in skeletal muscle under controlled mechanical loads was investigated. Static (0-20%) and cyclic (±2.5% amplitude, 0-20% mean, 1-3 Hz) strains and electrically paced isometric contractions (0.1-3 Hz, 0% strain) were applied to rat soleus incubated in 1 mM 20 kDa FITC-dextran. Dextran penetration, tissue porosity, and active force-length relationship over 0-20% strain correlated (r = 0.9-1.0), and all increased 1.5-fold from baseline at 0% to a maximum at 10% (L o ), demonstrating biologic significance of L o and impact of fiber size and distribution on function and pharmacokinetics. Overall penetration decreased but relative enhancement of penetration at L o increased with dextran size (4-150 kDa). Penetration increased linearly (0.084 mm/Hz) with cyclic stretch, demonstrating dispersion. Penetration increased with contraction rate by 1.5-fold from baseline to a maximum at 0.5 Hz, revealing architectural modulation of dispersion. Impact of architecture and dispersion on intramuscular transport was computationally modeled. Mechanical architecture and function underlie intramuscular pharmacokinetics and act in concert to effect resonance between optimal physiologic performance and drug uptake. Therapeutic management of characteristic function in tissue targets may enable a physiologic mechanism for controlled drug transport.

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Section: Resultssupporting

confidence: 88%

Intramuscular drug transport under mechanical loading: Resonance between tissue function and uptake

Minisini

Edelman

2009

Journal of Controlled Release

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“…The results for total water, Na, and K in older rats are in general agreement with previous reports (4,5,13). Despite the similarity in total water content, the inulin space of predominantly red muscle is larger than that of white muscle (4,13), partly as the result of the greater vascularity of red fibers (1,3).…”

supporting

confidence: 90%

“…Despite the similarity in total water content, the inulin space of predominantly red muscle is larger than that of white muscle (4,13), partly as the result of the greater vascularity of red fibers (1,3). This variation in extracellular fluid space, however, does not account for the concentrations of N a and K. T h e estimated content of intracellular K is less and that of N a is greater in red than in white fibers (4) ,…”

mentioning

confidence: 99%

Magnesium, Potassium, and Sodium in "Red" and "White" Muscle in the Rat

Chutkow

1973

Experimental Biology and Medicine

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Skeletal muscles may be classified as "red" (dark) and "white" (pale) depending on their gross color. The difference in color is due largely to the content of myoglobin in the muscle fibers. Mammalian muscles contain varying mixtures of dark and pale fibers and, therefore, are best described as "predominantly red" or "predominantly white." In the rat, the soleus is a good example of the former type of muscle; the superficial portion of the medial head of the gastrocnemius is an example of the latter tY Pe.Red and white fibers are morphologically and chemically dissimilar ( 1-3). The chemical dissimilarities include differences in the concentrations of potassium ( K ) and sodium ( N a ) ; predominantly white muscle contains more I ( and less N a than red (4, 5 ) .Potassium and also magnesium (Mg) are the most abundant intracellular inorganic cations in the soft tissues. The studies reported herein were undertaken to determine whether the distribution of Mg parallels that of K in the soleus and superficial portions of the gastrocnemius in the rat.Materials and Methods. Two groups of male albino rats (Sprague-Dawley strain) (weights of younger rats, 100-120 g, and of older rats, 250-300 g ) were used. The animals were anesthetized with ether and then exsanguinated by means of aortic puncture. The soleus, trimmed of all visible tendinous tissue, and a n equivalent amount of the medial head of the gastrocnemius were excised from each leg within 10 min of the animal's death. When measured, the total water content and extractable solids were determined by drying the muscles to constant weight at 110" for 24 hr and then perform-ing chloroform-methanol ( 2 : l ? vol/vol) extractions in Soxhlet apparatuses for 24 hr, using borosilicate thimbles. Both gastrocnemius muscles from one young animal were combined in one thimble and the soleus muscles in another. The soleus and gastrocnemius taken from one leg of an older rat were sufficient for both the water content and extractable solid determinations. Extracted and unextracted samples were transferred quantitatively to 5 .O-ml volumetric flasks. To each flask, 2 ml of concentrated HNO3 (reagent grade) was added, and the tissues were digested at 80 to 85". After dilution to 5.0 ml with distilled-deionized water, the digests were stored in polyethylene tubes until analyzed.Magnesium was determined by atomic absorption spectrophotometry ; N a and K were determined by flame photometry (6). Appropriate quantities of HN03 were added to all standards and blanks. Recoveries of known amounts of Mg and K added to the digestion mixtures were 100.4 t 1.870 and 99.3 2 0.4%, respectively; this indicated that there was no interfering effect from matrix.Unextracted muscles from one group of young rats served as controls for extracted muscles taken at the same time from a second group. The soleus and gastrocnemius from one leg of a large rat were used as unextracted controls for muscles excised from the other leg.For analysis of the significance of differences in the results, either a two-tai...

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“…Krebs solution without inulin or glucose. The concentration of inulin which had been diffused out from the muscle in the inulin-free solution was determined photometrically according to the method by Kobayashi & Yonemura (1967).…”

Section: Methodsmentioning

confidence: 99%

Contribution of an electrogenic sodium pump to membrane potential in mammalian skeletal muscle fibres.

Akaike¹

1975

The Journal of Physiology

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SUMMARY1. Relationship between the resting membrane potential and the changes in the intracellular Na and K concentrations ([Na]i and [K]1) was studied in 'Na-loaded' and 'K-depleted' soleus (SOL) muscles of rats which had fed a K-free diet for 40 and more days.2. The extracellular space of the muscles was not significantly different between normal and K-deficient rats. The inulin space in both the 'fresh' and 'Na-rich' muscles can be determined by the same function relating the space to the muscle weight.3. Presence of 2-5-15 mm-K in the recovery solution hyperpolarized the 'Na-rich' muscle fibres at the beginning of recovery. The hyperpolarized membrane potential exceeded, beyond the measured potential of 'fresh' muscle fibres, the theoretical potential derived from the ionic theory, or even beyond Ek. Then, the measured membrane potential declined progressively during the immersion in a recovery solution and returned to the steady-state value. When a considerable Na extrusion and K uptake took place, the measured membrane potential became equal to Ek. 6. The membrane potential obtained after inhibition of the electrogenic Na-pump with cooling or ouabain agrees well with that predicted by the 'constant-field' equation.7. The external Cl ions had a short-circuiting effect on the electrogenic Na-pumping activated on adding K ions.22-2 8. The replacement of Na ions in a recovery solution with Li ions resulted in a faster rate of depolarization from the maximal hyperpolarization.9. It is concluded that the resting membrane potential of 'Na-loaded' and 'K-depleted' SOL muscle fibres is the sum of an ionic diffusion potential predicted by either the Nernst equation or the constant-field equation and of the potential produced by an electrogenic Na-pump.

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The Extracellular Space in Red and White Muscles of the Rat

Cited by 27 publications

References 8 publications

Intramuscular drug transport under mechanical loading: Resonance between tissue function and uptake

Intramuscular drug transport under mechanical loading: Resonance between tissue function and uptake

Magnesium, Potassium, and Sodium in "Red" and "White" Muscle in the Rat

Contribution of an electrogenic sodium pump to membrane potential in mammalian skeletal muscle fibres.

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