scholarly journals THE LOCALIZATION OF CHOLINESTERASE ACTIVITY IN RAT CARDIAC MUSCLE BY ELECTRON MICROSCOPY

1964 ◽  
Vol 23 (2) ◽  
pp. 217-232 ◽  
Author(s):  
Morris J. Karnovsky
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Sarcoplasmic Reticulum ◽  
Enzymatic Activity ◽  
Cardiac Muscle ◽  
Heart Muscle ◽  
Cholinesterase Activity ◽  
Physiological Role ◽  
Ultrastructural Level ◽  
Formalin Fixed

A method has been developed for localizing sites of cholinesterase activity in rat cardiac muscle by electron microscopy. The method utilizes thiocholine esters as substrates, and is believed to be dependent on the reduction of ferricyanide to ferrocyanide by thiocholine released by enzymatic activity. The ferrocyanide thus formed is captured by copper to form fine, electron-opaque deposits of copper ferrocyanide, which sharply delineate sites of enzymatic activity at the ultrastructural level. Cholinesterase activity in formalin-fixed heart muscle was localized: (a) in longitudinal elements of the sarcoplasmic reticulum, but not in the T, or transverse, elements; and (b) in the A band, with virtually no activity noted in the M band, or in the H zone. The I band was also negative. No activity was detected in the sarcolemma, or in invaginations of the sarcolemma at the level of the Z band. The perinuclear element of the sarcoplasmic (endoplasmic) reticulum was frequently strongly positive. Activity at all sites was completely abolished by omitting the substrates, or by inhibition with eserine 10-4 M and diisopropylfluorophosphate 10-5 M. Eserine 10-5 M completely inhibited reaction in the sarcoplasmic reticulum, and virtually abolished that in the A band. These observations, together with the use of the relatively specific substrates and suitable controls to eliminate non-enzymatic staining, indicate that cholinesterase activity was being demonstrated. The activity in rat heart against different substrates was that of non-specific cholinesterases, in accordance with biochemical data. The activity in the A band was considered to be probably due to myosincholinesterase. It is proposed that the localization of cholinesterases in myocardium at the ultrastructural level should be taken into account in considering the possible functions of these myocardial enzymes, and it is hoped that knowledge of their localization will open up new avenues of approach in considering their physiological role in myocardium, which at present is not definitely known.

Butyrylcholinesterase in the Adult Rabbit Heart

1971 ◽  
Vol 29 ◽  
pp. 284-285
Author(s):  
M. Hagopian ◽  
V.M. Tennyson
Keyword(s):  
Endoplasmic Reticulum ◽  
Sarcoplasmic Reticulum ◽  
Papillary Muscle ◽  
Cholinesterase Activity ◽  
Ultrastructural Level ◽  
Rabbit Heart ◽  
Adult Rabbit ◽  
Intercalated Disc ◽  
Complex Forms ◽  
T System

The papillary muscle of the adult rabbit heart was studied by a modification of the copper thiocholine technique for the localization of cholinesterase activity. At the ultrastructural level the muscle shows evidence of butyrylcholinesterase (BuChE) in view of the fact that an electron-opaque reaction product, a copper thiocholine complex, forms when butyrylthiocholine (BuThCh) is used as substrate. The deposition of the reaction product was abolished by preincubation with iso-OMPA (tetraisopropyl pyrophosphortetramide) which specifically inhibits BuChE, but not by BW284C51 (1,5-bis [4-allyldimethylammoniumphenyl] penta-3-one dibromide) which inhibits acetylcholinesterase (AChE). When acetylthiocholine (AThCh) was used as substrate, no end product was found.BuChE activity is seen primarily in the terminal sacs of the sarcoplasmic reticulum (SR) in the region adjacent to the T system (Fig. 1), within the subsarcolemmal vesicles or tubules, and in the endoplasmic reticulum (Fig. 2) of the perinuclear zone. The reaction sites are found occasionally in some areas of the longitudinal elements of the SR, on the nuclear envelope (Fig.2), and in the cisterns which are associated with the intercalated disc. The discs are always negative.

scholarly journals CYTOCHEMICAL LOCALIZATION OF CHOLINESTERASE IN EMBRYONIC RABBIT CARDIAC MUSCLE

1970 ◽  
Vol 18 (1) ◽  
pp. 38-43 ◽  
Author(s):  
MARTIN HAGOPIAN ◽  
VIRGINIA M. TENNYSON ◽  
DAVID SPIRO
Keyword(s):  
Endoplasmic Reticulum ◽  
Sarcoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Cardiac Muscle ◽  
Golgi Complex ◽  
Cardiac Myocyte ◽  
Cholinesterase Activity ◽  
Cytochemical Localization ◽  
Contractile Tissue ◽  
Rabbit Embryos

Cardiac muscle of rabbit embryos from day 9 through day 18 of gestation was studied by a modification of the Koelle-Friedenwald copper thiocholine technique for the localization of cholinesterase activity. In the earlier stages of development a cholinesterase, presumed to be acetylcholinesterase from its substrate and inhibitor specificity, is found in the abundant, randomly dispersed rough surfaced endoplasmic reticulum of the myoblast. Cytochemical end product is also occasionally found in the nuclear envelope, Golgi complex and subsarcolemmal cisternae. The localization of the enzyme first in the rough surfaced endoplasmic reticulum and Golgi complex and at later stages in the sarcoplasmic reticulum is significant with regard to the differentiation of the cardiac myocyte. Furthermore, the presence of this enzyme in contractile tissue before the appearance of nerves or nerve endings demonstrates an acetylcholine-cholinesterase system of myogenic origin.

scholarly journals THE SARCOPLASMIC RETICULUM IN MUSCLE CELLS OF AMBLYSTOMA LARVAE

1956 ◽  
Vol 2 (4) ◽  
pp. 163-170 ◽  
Author(s):  
Keith R. Porter
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Sarcoplasmic Reticulum ◽  
Constant Width ◽  
Muscle Cells ◽  
Cell Types ◽  
Thin Sections ◽  
System A ◽  
Structural Relationships ◽  
Complex Membrane

Electron microscopy of thin sections of muscle fibers in myotomes of Amblystoma larvae has revealed the presence of a complex, membrane-limited system of canaliculi and vesicles which form a lace-like reticulum around and among the myofibrils. This seems to correspond to the sarcoplasmic reticulum of the earlier light microscopists and the endoplasmic reticulum of other cell types. The elements constituting the reticulum are disposed in a pattern which bears a constant relation to the bands of the adjacent myofibrils and is therefore repeated in each sarcomere. At the H band the system is transversely continuous but not so at other levels. Longitudinally continuity is interrupted at the Z bands where large vesicles belonging to adjacent sarcomere segments of the system face off on opposite sides of the band. The opposing faces of these vesicles are flat and separated by a space of more or less constant width, in which are located small, finger-shaped vesicles. In view of these and other close structural relationships with the myofibrils it seems appropriate to assign to the system a role in the conduction of the excitatory impulse.

scholarly journals Cholinesterase activity of lamellated sensory corpuscles in the rat lip

1986 ◽  
Vol 44 (4) ◽  
pp. 325-333 ◽  
Author(s):  
II-Sei Watanabe ◽  
Chizuka Ide
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Cholinesterase Activity ◽  
Light And Electron Microscopy ◽  
Reaction Products ◽  
Cell Plasma Membrane ◽  
Axon Terminals ◽  
Cell Plasma ◽  
Periaxonal Space ◽  
Lamellar Cell

Non-specific cholinesterase (ChE) activity was demonstrated in lamellated sensory corpuscles of the rat lip by light and electron microscopy using Karnovsky and Root's method. ChE activity was present in the interlamellar spaces between neighbouring lamellae as well as in the periaxonal space between axon terminals and their adjacent lamellae. Reaction products of ChE activity were also deposited in some caveolae of the lamellar cell plasma membrane, and in the cisternae of the rough endoplasmic reticulum as well as in the nuclear envelope of lamellar cell bodies. No definite reaction products were detected within the axon terminals. These findings show that the lamellated corpuscles in the rat lip, like other mechanoreceptors, have an intense ChE activity which is mainly associated with lamellar cells. It can be said that ChE histochemistry is useful to detect mechanoreceptors. The functional significance of ChE in mechanoreceptors is discussed.

scholarly journals Release of Ca2+ from a non-mitochondrial store site in peritoneal macrophages treated with saponin by inositol 1,4,5-trisphosphate

1984 ◽  
Vol 223 (1) ◽  
pp. 229-236 ◽  
Author(s):  
M Hirata ◽  
E Suematsu ◽  
T Hashimoto ◽  
T Hamachi ◽  
T Koga
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Sarcoplasmic Reticulum ◽  
Inhibitory Effect ◽  
Peritoneal Macrophages ◽  
Erythrocyte Ghosts ◽  
Cardiac Sarcoplasmic Reticulum ◽  
Intracellular Store ◽  
Inositol 1,4,5 Trisphosphate ◽  
Inside Out

The effects of inositol 1,4,5-trisphosphate, prepared from human erythrocyte ghosts, on Ca2+ release from intracellular store sites were studied in saponin-treated guinea pig peritoneal macrophages. Micromolar concentrations of inositol 1,4,5-trisphosphate released Ca2+ within 1 min from store sites which had accumulated Ca2+ in the presence of 10 mM-NaN3. In the presence of 10 mM-NaN3, the Ca2+ accumulated in the presence of oxalate was seen in the endoplasmic reticulum of saponin-treated macrophages by electron microscopy, indicating that the site of Ca2+ released by inositol 1,4,5-trisphosphate may be endoplasmic reticulum-like membranes. When the concentrations of free Ca2+ were over 3.5 × 10(-6) M, the release of Ca2+ by this agent was inhibited. This inhibition may be due to either the higher concentration of extra-vesicular free Ca2+ or the larger accumulation of Ca2+ into the store site or perhaps both effects. MgCl2 also had an inhibitory effect on the Ca2+ release. Inositol 1,4,5-trisphosphate also released Ca2+ from cardiac sarcoplasmic reticulum, but not from erythrocyte inside-out vesicles.

scholarly journals Smooth muscle expresses a cardiac/slow muscle isoform of the Ca2+-transport ATPase in its endoplasmic reticulum

1989 ◽  
Vol 257 (1) ◽  
pp. 117-123 ◽  
Author(s):  
F Wuytack ◽  
Y Kanmura ◽  
J A Eggermont ◽  
L Raeymaekers ◽  
J Verbist ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Endoplasmic Reticulum ◽  
Smooth Muscle ◽  
Sarcoplasmic Reticulum ◽  
Cardiac Muscle ◽  
Muscle Enzymes ◽  
Transport Atpase ◽  
Slow Twitch ◽  
Transport Atpases ◽  
Fast Twitch

Smooth muscle expresses in its endoplasmic reticulum an isoform of the Ca2+-transport ATPase that is very similar to or identical with that of the cardiac-muscle/slow-twitch skeletal-muscle form. However, this enzyme differs from that found in fast-twitch skeletal muscle. This conclusion is based on two independent sets of observations, namely immunological observations and phosphorylation experiments. Immunoblot experiments show that two different antibody preparations against the Ca2+-transport ATPase of cardiac-muscle sarcoplasmic reticulum also recognize the endoplasmic-reticulum/sarcoplasmic-reticulum enzyme of the smooth muscle and the slow-twitch skeletal muscle whereas they bind very weakly or not at all to the sarcoplasmic-reticulum Ca2+-transport ATPase of the fast-twitch skeletal muscle. Conversely antibodies directed against the fast-twitch skeletal-muscle isoform of the sarcoplasmic-reticulum Ca2+-transport ATPase do not bind to the cardiac-muscle, smooth-muscle or slow-twitch skeletal-muscle enzymes. The phosphorylated tryptic fragments A and A1 of the sarcoplasmic-reticulum Ca2+-transport ATPases have the same apparent Mr values in cardiac muscle, slow-twitch skeletal muscle and smooth muscle, whereas the corresponding fragments in fast-twitch skeletal muscle have lower apparent Mr values. This analytical procedure is a new and easy technique for discrimination between the isoforms of endoplasmic-reticulum/sarcoplasmic-reticulum Ca2+-transport ATPases.

scholarly journals Localization of Sulfonylurea Receptor Subunits, SUR2A and SUR2B, in Rat Heart

2007 ◽  
Vol 55 (8) ◽  
pp. 795-804 ◽  
Author(s):  
Ming Zhou ◽  
Hui-Jing He ◽  
Ryoji Suzuki ◽  
Ke-Xiang Liu ◽  
Osamu Tanaka ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Cell Membrane ◽  
Cardiac Muscle ◽  
Coronary Arteries ◽  
Rat Heart ◽  
Smooth Muscles ◽  
Sulfonylurea Receptor ◽  
Regulatory Subunits ◽  
Mitochondrial Fractions

To understand the possible functions and subcellular localizations of sulfonylurea receptors (SURs) in cardiac muscle, polyclonal anti-SUR2A and anti-SUR2B antisera were raised. Immunoblots revealed both SUR2A and SUR2B expression in mitochondrial fractions of rat heart and other cellular fractions such as microsomes and cell membranes. Immunostaining detected ubiquitous expression of both SUR2A and SUR2B in rat heart in the atria, ventricles, interatrial and interventricular septa, and smooth muscles and endothelia of the coronary arteries. Electron microscopy revealed SUR2A immunoreactivity in the cell membrane, endoplasmic reticulum (ER), and mitochondria. SUR2B immunoreactivity was mainly localized in the mitochondria as well as in the ER and cell membrane. Thus, SUR2A and SUR2B are not only the regulatory subunits of sarcolemmal KATP channels but may also function as regulatory subunits in mitochondrial KATP channels and play important roles in cardioprotection. (J Histochem Cytochem 55: 795–804, 2007)

scholarly journals CARDIAC MUSCLE

1968 ◽  
Vol 36 (3) ◽  
pp. 497-526 ◽  
Author(s):  
Joachim R. Sommer ◽  
Edward A. Johnson
Keyword(s):  
Electron Microscopy ◽  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Guinea Pig ◽  
Cardiac Muscle ◽  
Extracellular Space ◽  
Light And Electron Microscopy ◽  
Rabbit Heart ◽  
Contraction Coupling ◽  
The Difference

With light and electron microscopy a comparison has been made of the morphology of ventricular (V) and Purkinje (P) fibers of the hearts of guinea pig, rabbit, cat, dog, goat, and sheep. The criteria, previously established for the rabbit heart, that V fibers are distinguished from P fibers by the respective presence and absence of transverse tubules is shown to be true for all animals studied. No evidence was found of a permanent connection between the sarcoplasmic reticulum and the extracellular space. The sarcoplasmic reticulum (SR) of V fibers formed couplings with the sarcolemma of a transverse tubule (interior coupling) and with the peripheral sarcolemma (peripheral coupling), whereas in P fibers the SR formed only peripheral couplings. The forms of the couplings were identical. The significance, with respect to excitation-contraction coupling, of the difference in the form of the couplings in cardiac versus skeletal muscle is discussed together with the electrophysiological implications of the differing geometries of bundles of P fibers from different animals.

scholarly journals TRIC-A Channel Maintains Store Calcium Handling by Interacting With Type 2 Ryanodine Receptor in Cardiac Muscle

2020 ◽  
Vol 126 (4) ◽  
pp. 417-435 ◽  
Author(s):  
Xinyu Zhou ◽  
Ki Ho Park ◽  
Daiju Yamazaki ◽  
Pei-hui Lin ◽  
Miyuki Nishi ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Sarcoplasmic Reticulum ◽  
Cardiac Muscle ◽  
Ryanodine Receptor ◽  
Calcium Handling ◽  
Striated Muscles ◽  
Human Embryonic Kidney Cells ◽  
Intracellular Ca ◽  
Ion Conducting

Rationale: Trimeric intracellular cation (TRIC)-A and B are distributed to endoplasmic reticulum/sarcoplasmic reticulum intracellular Ca 2+ stores. The crystal structure of TRIC has been determined, confirming the homotrimeric structure of a potassium channel. While the pore architectures of TRIC-A and TRIC-B are conserved, the carboxyl-terminal tail (CTT) domains of TRIC-A and TRIC-B are different from each other. Aside from its recognized role as a counterion channel that participates in excitation-contraction coupling of striated muscles, the physiological function of TRIC-A in heart physiology and disease has remained largely unexplored. Objective: In cardiomyocytes, spontaneous Ca 2+ waves, triggered by store overload–induced Ca 2+ release mediated by the RyR 2 (type 2 ryanodine receptor), develop extrasystolic contractions often associated with arrhythmic events. Here, we test the hypothesis that TRIC-A is a physiological component of RyR 2 -mediated Ca 2+ release machinery that directly modulates store overload–induced Ca 2+ release activity via CTT. Methods and Results: We show that cardiomyocytes derived from the TRIC-A −/− (TRIC-A knockout) mice display dysregulated Ca 2+ movement across sarcoplasmic reticulum. Biochemical studies demonstrate a direct interaction between CTT-A and RyR 2 . Modeling and docking studies reveal potential sites on RyR 2 that show differential interactions with CTT-A and CTT-B. In HEK293 (human embryonic kidney) cells with stable expression of RyR 2 , transient expression of TRIC-A, but not TRIC-B, leads to apparent suppression of spontaneous Ca 2+ oscillations. Ca 2+ measurements using the cytosolic indicator Fura-2 and the endoplasmic reticulum luminal store indicator D1ER suggest that TRIC-A enhances Ca 2+ leak across the endoplasmic reticulum by directly targeting RyR 2 to modulate store overload–induced Ca 2+ release. Moreover, synthetic CTT-A peptide facilitates RyR 2 activity in lipid bilayer reconstitution system, enhances Ca 2+ sparks in permeabilized TRIC-A −/− cardiomyocytes, and induces intracellular Ca 2+ release after microinjection into isolated cardiomyocytes, whereas such effects were not observed with the CTT-B peptide. In response to isoproterenol stimulation, the TRIC-A −/− mice display irregular ECG and develop more fibrosis than the WT (wild type) littermates. Conclusions: In addition to the ion-conducting function, TRIC-A functions as an accessory protein of RyR 2 to modulate sarcoplasmic reticulum Ca 2+ handling in cardiac muscle.

scholarly journals STUDIES ON THE ENDOPLASMIC RETICULUM

1957 ◽  
Vol 3 (2) ◽  
pp. 269-300 ◽  
Author(s):  
Keith R. Porter ◽  
George E. Palade
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Sarcoplasmic Reticulum ◽  
Muscle Contraction ◽  
Striated Muscle ◽  
Cell Types ◽  
Entire System ◽  
Structural Components ◽  
Reticular Structure ◽  
Vacuolar System

Several types of striated muscle have been examined by the technics of electron microscopy and the findings in myotome fibers of Amblystoma larvae, the sartorius, and cardiac muscle of the rat are reported on in some detail. Particular attention has been given to structural components of the interfibrillar sarcoplasm and most especially to a finely divided, vacuolar system known as the sarcoplasmic reticulum. This consists of membrane-limited vesicles, tubules, and cisternae associated in a continuous reticular structure which forms lace-like sleeves around the myofibrils. It shows a definable organization which repeats with each sarcomere of the fiber so that the entire system is segmented in phase with the striations of the associated myofibrils. Details of these repetitive patterns are presented diagrammatically in Text-figs. 1, 2, and 3 on pages 279, 283, and 288 respectively. The system is continuous across the fiber at the H band level and largely discontinuous longitudinally because of interruptions in the structure at the I and Z band levels. The structure of the system relates it to the endoplasmic reticulum of other cell types. The precise morphological relation of the reticulum to the myofibrils, with specializations opposite the different bands, prompts the supposition that the system is functionally important in muscle contraction. In this regard it is proposed that the membrane limiting the system is polarized like the sarcolemma and that the corresponding potential difference is utilized in the intracellular distribution of the excitatory impulse.

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