Calcium and Magnesium Movements Through Sarcoplasmic Reticulum, Endoplasmic Reticulum, and Mitochondria

1988 ◽  
pp. 221-229 ◽  
Author(s):  
A. V. Somlyo ◽  
M. Bond ◽  
R. Broderick ◽  
A. P. Somlyo
Keyword(s):  
Endoplasmic Reticulum ◽  
Sarcoplasmic Reticulum ◽  
Calcium And Magnesium

The Endoplasmic Reticulum-Sarcoplasmic Reticulum Connection

1993 ◽  
Vol 209 (1) ◽  
pp. 140-148 ◽  
Author(s):  
Antonello Villa ◽  
Paola Podini ◽  
Alessandra Nori ◽  
Maria Carla Panzeri ◽  
Adelina Martini ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Sarcoplasmic Reticulum

cADP-ribose releases Ca2+ from cardiac sarcoplasmic reticulum independently of ryanodine receptor

1997 ◽  
Vol 273 (3) ◽  
pp. H1082-H1089 ◽  
Author(s):  
P. Lahouratate ◽  
J. Guibert ◽  
J. F. Faivre
Keyword(s):  
Endoplasmic Reticulum ◽  
Sarcoplasmic Reticulum ◽  
Ryanodine Receptor ◽  
Sea Urchin ◽  
Calcium Release ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Cardiac Sarcoplasmic Reticulum ◽  
Consistent Effect ◽  
Cyclic Adp Ribose

Cyclic ADP-ribose (cADPR), an endogenous metabolite of beta-NAD+, activates Ca2+ release from endoplasmic reticulum in sea urchin eggs via the ryanodine receptor (RyR) pathway. A similar role has been proposed in cardiac sarcoplasmic reticulum (SR), although this remains controversial. We therefore investigated the ability of cADPR to induce Ca2+ release from canine cardiac SR microsomes using fluo 3 to monitor extravesicular Ca2+ concentration. We found that cADPR induced Ca2+ release in a concentration-dependent manner, whereas neither its precursor, NAD+, nor its metabolite, ADP-ribose, elicited a consistent effect. In addition, an additive effect on calcium release between cADPR and 9-Me-7-Br-eudistomin-D (MBED), an activator of RyR, was found as well as no cross-desensitization between cADPR and MBED. Specific blockers of the RyR did not abolish the cADPR-induced Ca2+ release. These results provide evidence for cADPR-induced Ca2+ release from dog cardiac SR via a novel mechanism which is independent of RyR activation.

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.

Tunneling cell processes in myocytes of stretched mouse atria

1987 ◽  
Vol 253 (2) ◽  
pp. H432-H443
Author(s):  
E. Page ◽  
G. E. Goings ◽  
B. Power ◽  
J. Upshaw-Earley
Keyword(s):  
Endoplasmic Reticulum ◽  
Sarcoplasmic Reticulum ◽  
Ionic Composition ◽  
Interstitial Space ◽  
Cytoplasmic Matrix ◽  
Cytoplasmic Structure ◽  
Section Electron ◽  
Cell Processes ◽  
Peptide Secretion

Serial section electron micrographs of mouse atria stretched in vitro show that myocytes have cell processes which tunnel into adjacent myocytes for 8 microns or more. The tunneling cell processes (TCP) (diam 4–6.2 microns) lack myofibrils and organelles associated with atrial peptide secretion. The glycogen-rich TCP cytoplasmic matrix contains conspicuous tubules and vesicles originating from endoplasmic reticulum and resembling free sarcoplasmic reticulum (SR). TCP are surrounded by a plasmalemma derived from their myocyte of origin, the plasmalemma of the tunneled myocyte, and an intervening narrow compartment continuous with the interstitial space. Profiles having the characteristics cytoplasmic structure of TCP are also found both in the interstitial space between myocytes and near the longitudinal terminations where myocyte ends about on the interstitial space. We suggest that TCP tubules and vesicles may proliferate and/or transport in response to stretch, might be free SR, and may respond to stretch-activated changes in ionic composition or potential of the surrounding myocyte and narrow intercellular compartment.

scholarly journals Detection of the membrane-calcium distribution during mitosis in Haemanthus endosperm with chlorotetracycline.

1980 ◽  
Vol 87 (1) ◽  
pp. 23-32 ◽  
Author(s):  
S M Wolniak ◽  
P K Hepler ◽  
W T Jackson
Keyword(s):  
Endoplasmic Reticulum ◽  
Sarcoplasmic Reticulum ◽  
Membrane System ◽  
Mitotic Apparatus ◽  
Calcium Distribution ◽  
Detergent Extraction ◽  
Claw Muscle ◽  
Cellular Ca ◽  
Polar Distribution ◽  
Total Elimination

The distribution of membrane-associated calcium has been determined at various stages of mitosis in Haemanthus endosperm cells with the fluorescent chelate probe chlorotetracycline (CTC). CTC fluorescence in Haemanthus has two components: punctate, because of mitochondrial and plastid membrane-Ca++; and diffuse, primarily because of Ca++ associated with endoplasmic reticulum membranes. Punctate fluorescence assumes a polar distribution throughout mitosis. Cones of diffuse fluorescence in the chromosomse-to-pole regions of the metaphase spindle appear to coincide with the kinetochore fibers; during anaphase, the cones of fluorescence coalesce and this region of the spindle exhibits uniform diffuse fluorescence. Perturbation of the cellular Ca++ distribution by treatment with lanthanum, procaine, or EGTA results in a loss of diffuse fluorescence with no accompanying change in the intensity of punctate fluorescence. Detergent extraction of cellular membranes causes a total elimination of CTC fluorescence. CTC fluorescence of freshly teased crayfish claw muscle sarcoplasmic reticulum coincides with the A bands and is reduced by perfusion with lanthanum, procaine, and EGTA in a manner similar to that for diffuse fluorescence in the endosperm cells. These results are consistent with the hypothesis that a membrane system in the chromosome-to-pole region of the mitotic apparatus functions in the localized release of sequestered Ca++, thereby regulating the mechanochemical events of mitosis.

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