scholarly journals Metabolic recovery of acidotic rabbit cardiac muscle: effects of low pH and oxygen shortage.

1989 ◽  
Vol 65 (4) ◽  
pp. 909-916 ◽  
Author(s):  
F Mast ◽  
G Elzinga
Keyword(s):  
Cardiac Muscle ◽  
Low Ph ◽  
Metabolic Recovery ◽  
Oxygen Shortage

Anchorfibers and the Topography of Junctional SR

1977 ◽  
Vol 35 ◽  
pp. 582-583
Author(s):  
James Junker ◽  
Joachim R. Sommer
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Cardiac Muscle ◽  
Single Filament ◽  
Relaxation Cycle ◽  
10 Nm Filaments ◽  
Junctional Sarcoplasmic Reticulum

Junctional sarcoplasmic reticulum (JSR) in all its forms (extended JSR, JSR of couplings, corbular SR) in both skeletal and cardiac muscle is always located at the Z - I regions of the sarcomeres. The Z tubule is a tubule of the free SR (non-specialized SR) which is consistently located at the Z lines in cardiac muscle (1). Short connections between JSR and Z lines have been described (2), and bundles of filaments at Z lines have been seen in skeletal (3) and cardiac (4) muscle. In opossum cardiac muscle, we have seen bundles of 10 nm filaments stretching across interfibrillary spaces and adjacent myofibrils with extensions to the plasma- lemma in longitudinal (Fig. 1) and transverse (Fig. 2) sections. Only an occasional single filament is seen elsewhere along a sarcomere. We propose that these filaments represent anchor fibers that maintain the observed invariant topography of the free SR and JSR throughout the contraction-relaxation cycle.

Relationship between golgi apparatus and axonal reticulum in sympathetic ganglion cells

1978 ◽  
Vol 36 (2) ◽  
pp. 598-599
Author(s):  
J. Quatacker ◽  
W. De Potter
Keyword(s):  
Golgi Apparatus ◽  
Sympathetic Ganglion ◽  
Phosphotungstic Acid ◽  
Ganglion Cells ◽  
Low Ph ◽  
Dense Core ◽  
Dense Core Vesicles ◽  
Large Dense Core Vesicles ◽  
Cervical Ganglia ◽  
Axoplasmic Reticulum

Mucopolysaccharides have been demonstrated biochemically in catecholamine-containing subcellular particles in different rat, cat and ox tissues. As catecholamine-containing granules seem to arise from the Golgi apparatus and some also from the axoplasmic reticulum we examined wether carbohydrate macromolecules could be detected in the small and large dense core vesicles and in structures related to them. To this purpose superior cervical ganglia and irises from rabbit and cat and coeliac ganglia and their axons from dog were subjected to the chromaffin reaction to show the distribution of catecholamine-containing granules. Some material was also embedded in glycolmethacrylate (GMA) and stained with phosphotungstic acid (PTA) at low pH for the detection of carbohydrate macromolecules.The chromaffin reaction in the perikarya reveals mainly large dense core vesicles, but in the axon hillock, the axons and the terminals, the small dense core vesicles are more prominent. In the axons the small granules are sometimes seen inside a reticular network (fig. 1).

Neuronal and Extraneuronal Uptake of 3H-Norepinephrine in the Heart of the Active Bat: An Electron Microscopic Radioautographic Study

1973 ◽  
Vol 31 ◽  
pp. 522-523
Author(s):  
Martin Hagopian ◽  
Michael D. Gershon ◽  
Eladio A. Nunez
Keyword(s):  
Smooth Muscle ◽  
Monoamine Oxidase ◽  
Vascular Smooth Muscle ◽  
Cardiac Muscle ◽  
Maximum Rate ◽  
External Medium ◽  
Extraneuronal Uptake ◽  
Electron Microscopic ◽  
Cardiac Tissues ◽  
High Affinity

The ability of cardiac tissues to take up norepinephrine from an external medium is well known. Two mechanisms, called Uptake and Uptake respectively by Iversen have been differentiated. Uptake is a high affinity system associated with adrenergic neuronal elements. Uptake is a low affinity system, with a higher maximum rate than that of Uptake. Uptake has been associated with extraneuronal tissues such as cardiac muscle, fibroblasts or vascular smooth muscle. At low perfusion concentrations of norepinephrine most of the amine taken up by Uptake is metabolized. In order to study the localization of sites of norepinephrine storage following its uptake in the active bat heart, tritiated norepinephrine (2.5 mCi; 0.064 mg) was given intravenously to 2 bats. Monoamine oxidase had been inhibited with pheniprazine (10 mg/kg) one hour previously to decrease metabolism of norepinephrine.

Morphological Basis of the Disparity Between Muscle Length and Sarcomere Length in the Myocardium

1973 ◽  
Vol 31 ◽  
pp. 422-423
Author(s):  
G.E. Adomian ◽  
L. Chuck ◽  
W.W. Pannley
Keyword(s):  
Cardiac Muscle ◽  
Sarcomere Length ◽  
Muscle Length ◽  
Contractile Force ◽  
Direct Function ◽  
Morphological Basis ◽  
Tension Curve

Sonnenblick, et al, have shown that sarcomeres change length as a function of cardiac muscle length along the ascending portion of the length-tension curve. This allows the contractile force to be expressed as a direct function of sarcomere length. Below L max, muscle length is directly related to sarcomere length at lengths greater than 85% of optimum. However, beyond the apex of the tension-length curve, i.e. L max, a disparity occurs between cardiac muscle length and sarcomere length. To account for this disproportionate increase in muscle length as sarcomere length remains relatively stable, the concept of fiber slippage was suggested as a plausible explanation. These observations have subsequently been extended to the intact ventricle.

High Resolution Stereography of Complementary Freeze-Fracture Replicas Reveals the Presence of Depressions Opposite Membrane Associated Particles of Split Membranes

1971 ◽  
Vol 29 ◽  
pp. 442-443
Author(s):  
Russell L. Steere
Keyword(s):  
High Resolution ◽  
Cardiac Muscle ◽  
Electron Micrographs ◽  
Chromic Acid ◽  
Freeze Fracture ◽  
Distilled Water ◽  
Fine Scale ◽  
Acid Cleaning ◽  
Cleaning Solution

Complementary replicas have revealed the fact that the two common faces observed in electron micrographs of freeze-fracture and freeze-etch specimens are complementary to each other and are thus the new faces of a split membrane rather than the original inner and outer surfaces (1, 2 and personal observations). The big question raised by published electron micrographs is why do we not see depressions in the complementary face opposite membrane-associated particles? Reports have appeared indicating that some depressions do appear but complementarity on such a fine scale has yet to be shown.Dog cardiac muscle was perfused with glutaraldehyde, washed in distilled water, then transferred to 30% glycerol (material furnished by Dr. Joaquim Sommer, Duke Univ., and VA Hospital, Durham, N.C.). Small strips were freeze-fractured in a Denton Vacuum DFE-2 Freeze-Etch Unit with complementary replica tooling. Replicas were cleaned in chromic acid cleaning solution, then washed in 4 changes of distilled water and mounted on opposite sides of the center wire of a Formvar-coated grid.

Mechanism of Human Plasminogen Activation by Streptokinase and Human Plasmin

1964 ◽  
Vol 11 (01) ◽  
pp. 085-093
Author(s):  
W. F Blatt ◽  
JL Gray ◽  
H Jensen
Keyword(s):  
Proteolytic Activity ◽  
Low Ph ◽  
Plasminogen Activation ◽  
Sensitive Tool ◽  
Human Plasminogen

SummaryA sensitive tool has been described for measuring fibrinolysis in reconstituted systems using thrombelastography. Activator mixtures with no appreciable proteolytic activity can similarly be tested in this system when the fibrinogen utilized has sufficient plasminogen present. Exposure of human plasminstreptokinase mixtures formed at pH 7.0 to acid conditions produced a striking loss of activator activity which could not be ascribed to low pH lability of the components, nor to plasmin action on the SK at pH 2.0. This is additional evidence for the hypothesis that human plasmin interacts with SK to form a complex capable of converting human and bovine plasminogen to plasmin.

Influence of Polymer Charge, Temperature, and Surfactants on Surface Sizing of Liner and Greaseproof Paper With Hydrophobically Modified Starch

TAPPI Journal ◽  
2009 ◽  
Vol 8 (2) ◽  
pp. 33-38 ◽  
Author(s):  
ANNA JONHED ◽  
LARS JÄRNSTRÖM
Keyword(s):  
Phase Separation ◽  
Contact Angles ◽  
Low Ph ◽  
Hydrophobically Modified ◽  
Paper Sizing ◽  
Surface Sizing ◽  
Separation Temperature ◽  
Hydrophobic Nature ◽  
Sizing Agents ◽  
Charge Temperature

The aim of this study was to investigate the properties of hydrophobically modified (HM) quaterna-ry ammonium starch ethers for paper sizing. These starches possess temperature-responsive properties; that is, gelation or phase separation occurs at a certain temperature upon cooling. This insolubility of the HM starches in water at room temperature improved their performance as sizing agents. The contact angles for water on sized liner were substantially larger than on unsized liner. When the application temperature was well above the critical phase-separation temperature, larger contact angles were obtained for liner independently of pH compared with those at the lower application temperature. Cobb60 values for liner decreased upon surface sizing, with a low pH and high application temperature giving lower water penetration. Contact angles on greaseproof paper decreased upon sur-face sizing as compared to unsized greaseproof paper, independently of pH and temperature. Greaseproof paper showed no great difference between unsized substrates and substrates sized with HM starch at different pH. This is probably due to the already hydrophobic nature of greaseproof paper. However, the Cobb60 values increased at low pH and low application temperature. Surfactants were added to investigate how they affect the sized surface. Addition of surfactant reduces the contact angles, in spite of indications of complex formation.

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