Inward Spread of Activation in Twitch Skeletal Muscle Fibers

González‐Serratos, Hugo

doi:10.1002/cphy.cp100112

Cited by 6 publications

(4 citation statements)

References 77 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…There was a tendency for mitochondrial Ca content to be higher in the regions of supercontracted sarcomeres than in those of superstretched sarcomeres, but no attempt was made to quantitate this observation . The other elements measured by electron probe analysis in mitochondria were within the range of frog-to-frog variation found in this and previous studies (29,43,65,66) . Pretreatment with valinomycin (5 jM for 2 h at 2°C) blocked the caffeine-induced increase in mitochondrial Ca.…”

Section: Mitochondrial Ca Uptakesupporting

confidence: 86%

Calcium and magnesium contents and volume of the terminal cisternae in caffeine-treated skeletal muscle.

Yoshioka¹,

Somlyo²

1984

The Journal of Cell Biology

View full text Add to dashboard Cite

(a) The effects of caffeine on the composition and volume of the terminal cisternae (TC) of the sarcoplasmic reticulum (SR) in frog skeletal muscle were determined with rapid freezing, electron microscopy, and electron probe analysis . (b) Caffeine (5 mM) released -65% of the Ca content of the TIC in 1 min and 84% after 3 min . The release of Ca from the TIC was associated with a highly significant increase in its Mg content . This increase in Mg was not reduced by valinoMycin . There was also a small increase in the K Content of the TIC at 1 min, although not after 3 min of caffeine contracture . (c) On the basis of the increase in Mg content during caffeine contracture and during tetanus (Somlyo, A . V., H . Gonzalez-Serratos, H. Shuman, G . McClellan, and A. P. Somlyo, 1981, J. Cell Biol., 90 :577-594), we suggest that both mechanisms of Ca release are associated with an increase in the Ca and Mg permeability of the SR membranes, the two ions possibly moving through a common channel . (d) There was a significant increase in the P content of the TC during caffeine contracture, while in tetanized muscle (see reference above) there was no increase in the P content of the TC. (e) Mitochondrial Ca content was significantly increased (at 1 and at 3 min) during caffeine contracture . Valinomycin (5 MM) blocked this mitochondria) Ca uptake . (f) The sustained Ca release caused by caffeine in situ contrasts with the transient Ca release observed in studies of fragmented SR preparations, and could be explained by mediation of the caffeine-induced Ca release by a second messenger produced more readily in intact muscle than in isolated SR. (g) The TIC were not swollen in rapidly frozen, caffeine-treated muscles, in contrast to the swelling of the TIC observed in conventionally fixed, caffeine-treated preparation, the latter finding being in agreement with previous studies . (h) The fractional volume of the TIC in rapidly frozen control (resting) frog semitendinosus muscles (-2 .1%) was less than the volume (-2 .5%) after glutaraldehyde-osmium fixation .It is well known that caffeine can cause contraction of skeletal muscle without depolarization (2, 11, 47) through the release of calcium from the sarcoplasmic reticulum (75, 76; for review, see reference 20), and swelling of the sarcoplasmic reticulum (SR)' has been observed in electron micrographs of muscles that were fixed conventionally (with glutaraldehydeosmium) during caffeine contracture (31,72,80). Recently, it has become possible to quantitate in situ with electron probe analysis not only the amount of Ca released, but also I Abbreviations used in this paper: EDL, extensor digitorum longus IV (muscle) ; SEMI, semitendinosus (muscle) ; SR, sarcoplasmic reticulum; TC, terminal cisternae; T-tubule, transverse tubule. the associated movement of other ions (K, Mg) into the SR during tetanus (43,65,66). In addition, the preservation of tissues through rapid freezing, rather than by the use ofliquid fixatives, has revealed that swelling of the SR in conventiona...

show abstract

Section: Mitochondrial Ca Uptakesupporting

confidence: 86%

Calcium and magnesium contents and volume of the terminal cisternae in caffeine-treated skeletal muscle.

Yoshioka¹,

Somlyo²

1984

The Journal of Cell Biology

View full text Add to dashboard Cite

show abstract

“…We also derived relaxation velocities (1 .7-6.8,um/s) by linear regression analysis, since we did not identify significant segments requiring exponential fitting. With respect to the pattern of relaxation, it should be noted that the single myocytes used in our experiments were free of surrounding connective tissue, and were observed without restraint at either end; therefore, the origin of linear forces determining sarcomere elongation was likely to be internal (Gonzalez-Serratos, 1971), and quite different from that in whole fibers . It is of interest that identical temperature dependences (Q,o = 2.2) were observed for the velocity of shortening and the velocity of relaxation, as well as for the beating rates (Table I).…”

Section: Resultsmentioning

confidence: 96%

“…Cells were observed under a 40X bright-field objective (Carl Zeiss, New York), on a microscope (E. Leitz, Inc., Rockleigh, NJ) equipped with a high-speed (0-500 frames/s) 16-mm film camera . In order to observe the striations clearly, the substage condenser iris diaphragm was closed so as to decrease the illuminating cone given a numerical aperture (NA) of 0.26-0 .24 (Gonzalez-Serratos, 1971) . Although this reduces the amount of light that is effectively passing through the objective, it is possible to see the muscle fiber with ordinary light .…”

Section: Cinemicrophotographymentioning

confidence: 99%

Patterns of sarcomere activation, temperature dependence, and effect of ryanodine in chemically skinned cardiac fibers.

Lundblad¹,

González‐Serratos²,

Inesi³

et al. 1986

The Journal of General Physiology

View full text Add to dashboard Cite

Functionally skinned and electrochemically shunted myocytes were prepared by perfusing rat hearts with collagenase in order to obtain a technically improved measurement of sarcomere dynamics and to evaluate the role of sarcoplasmic reticulum in situ with respect to contractile activation . In the presence of micromolar calcium, the myocytes exhibited phasic and propagated contraction waves beginning at one end and proceeding along the myocyte . Beating rates, the propagation velocity of the activation wave, and single sarcomere shortening and relaxation velocities were obtained by manual or automated analysis of 16-mm film recorded at 170 frames/s from a camera attached to a microscope that was equipped with a temperature-controlled stage . In parallel experiments, calcium accumulation by the sarcoplasmic reticulum of the myocytes in situ was measured by direct isotopic tracer methods . The frequency (10-38 min-') of spontaneous contractions, the velocity (1 .9-7 .4 Am-s-') of sarcomere shortening, and the velocity (1 .7-6 .8 um-s -') of sarcomere relaxation displayed identical temperature dependences (QIo = 2 .2), which are similar to that of the calcium pump of sarcoplasmic reticulum and are consistent with a rate limit imposed by enzyme-catalyzed mechanisms on all these parameters . On the other hand, the velocity (77-159 ,um-s') of sequential sarcomere activation displayed a lower temperature dependence (QIo = 1 .5), which is consistent with a diffusion-limited and self-propagating release of calcium from one sarcomere to the other . The phasic contractile activity of the dissociated myocytes was inhibited by 10 -$-10 6 M ryanodine (and not by myolemmal calcium blockers) under conditions in which calcium accumulation by sarcoplasmic reticulum in situ was demonstrated to proceed optimally . The effect of ryanodine is attributed to an interaction of this drug with sarcotubular structures, producing inhibition of calcium release from the sarcoplasmic reticAddress reprint requests to Dr . P . Paolini,

show abstract

“…Через 60 діб від початку моделювання в аксоплазмі спостерігаються структурні зміни, що дозволяють говорити про порушення аксонного транспорту [15]. Агрегація мікротрубочок і нейрофіламентів може проходити в умовах підвищеної кислотності аксоплазми.…”

Section: рисunclassified

Гістометрична Та Ультраструктурна Організація Нервово-М’язових Закінчень М’язів Передньої Стінки Живота При Постопераційній Вентральній Грижі

Василик¹

2020

Scientific and practical journal

View full text Add to dashboard Cite

Резюме. Актуальність. Відомо, що при вентральних грижах різко знижується функція м’язів передньої стінки живота внаслідок гіпотрофії м’язових волокон. При цьому питання про перебудову периферійного нервового апарату (нервово-м’язових закінчень та аксо-м’язових синапсів) за таких умов залишається маловивченим. Мета роботи полягала у вивченні динаміки гісто-ультраструктурних змін аксо-м’язових синапсів прямого м’язу живота при післяопераційній вентральній грижі. Матеріали і методи дослідження. У 10 щурів лінії Вістар моделювали вентральну грижу і виводили з експерименту через 30, 60 і 90 діб для дослідження периферійного нервового апарату прямого м’язу живота гістологічними та електронно-мікроскопічним методами. Контрольну групу (КГ) склали 10 інтактних безпородних щурів-самців віком 120 діб. Результати. Результати, отримані нами, показують, що при паховій грижі до наявних деструктивних змін претермінальних волокон і аксонних терміналей приєднується недостатність передачі імпульсів, яка обумовлена глибокими дегенеративними змінами в постсинаптичних мембранах, які посилюють вплив інших несприятливих факторів на розвиток поперечносмугастого м’язу. Висновки. В ранні терміни після моделювання вентральної грижі в ділянці післяопераційного шва спостерігаються дистрофічно-деструктивні зміни нервово-м’язових закінчень, які в пізні терміни поєднуються з процесами вторинної реінервації м’язових волокон. Посилений спраутинг аксонів супроводжується збільшенням величини рухових одиниць, що на фоні малорозвинених аксо-м’язових синапсів веде до зниження силових здібностей м’язів передньої стінки живота. Це може бути морфологічним субстратом і причиною виникнення післяопераційних вентральних гриж.

show abstract

Inward Spread of Activation in Twitch Skeletal Muscle Fibers

Abstract: The sections in this article are: Inward Spread of the Excitatory Process Development of the Problem Role of the Action Potential New Facts and Theories Morphological Evidence Hypothesis Morphological Corroboration Mec… Show more

Cited by 6 publications

References 77 publications

Calcium and magnesium contents and volume of the terminal cisternae in caffeine-treated skeletal muscle.

Calcium and magnesium contents and volume of the terminal cisternae in caffeine-treated skeletal muscle.

Patterns of sarcomere activation, temperature dependence, and effect of ryanodine in chemically skinned cardiac fibers.

Гістометрична Та Ультраструктурна Організація Нервово-М’язових Закінчень М’язів Передньої Стінки Живота При Постопераційній Вентральній Грижі

Contact Info

Product

Resources

About