ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1432-0878
    Keywords: Vascular smooth muscle ; Spontaneously hypertensive rat ; Reaggregate cultures ; Ultrastructure ; Collagen synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Vascular smooth muscle cells were taken from the aortae of the WKY (normotensive) and SHR (spontaneously hypertensive) strains of rat by enzymatic dispersion and put into reaggregate culture. Initially the cells became individual spheroids having average diameters of 10 μm and surfaces that were either rough or smooth. The cells were far more complex than they appeared on their surfaces; after one day in culture, there was considerable internal variation in these cells. All the cells, whether WKY or SHR, lost the bulk of their cytoplasmic contents (including myofilaments, many mitochondria, and vesicular structures) in the early stages of culture and eventually became flattened. After 14 days in culture, these modified cells collected to form reaggregates that were commonly roughly spherical and several hundred μm in diameter. These reaggregates consisted of peripheral regions made up of several layers of flattened cells overlying cores formed by glia-like networks of cells similar in cytological appearance to the cells at the periphery. The meshes formed in this way contained cellular debris derived from dead cells or extrusion of cellular contents. It appears that SHR cells are quicker to form reaggregates than are WKY cells. Yet the SHR cells retained a rounded conformation after five days, whereas the WKY cells were more flattened and formed a more discrete aggregate at this stage of culture. However, by the fourteenth day of culture, differences between the two cell strains were not so pronounced, as far as could be judged by observations made with scanning and transmission electron microscopy. Both WKY and SHR cells at 14 days appeared highly secretory, possessing large Golgi systems as well as numerous ER cisternae and mitochondria. SHR cells produced greater amounts of connective tissue at all stages of culture than did WKY cells, indicating that a similar difference may contribute to the hypertension which develops naturally in situ in SHR animals.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1432-0878
    Keywords: Mammalian cardiac muscle ; T system ; Longitudinal tubules ; Electronopaque diffusion tracers ; Excitation-contraction coupling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Colloidal ThO2 particles (diameter of ∼ 60 Å) were used as electron-opaque markers to trace the “intracellular” compartments continuous with the bulk interstitial fluid of guinea pig ventricular muscle. Beating and quiescent hearts in a Langendorff preparation were perfused for 30 min with oxygenated Ringer solution containing 1% ThO2. The hearts were immediately fixed by perfusing with glutaraldehyde solution. The colloidal ThO2 particles entered into many of the T tubules and into longitudinallyrunning tubules. No differences in distribution of ThO2 were observed in a heart which was not exposed to ThO2 until after it was fixed. Tracer did not penetrate into the intercalated disk clefts in the guinea pig hearts and one frog heart used for comparison. Tubular profiles filled with ThO2 were not seen in frog heart, an observation which confirms the absence of T tubules in this amphibian. It is concluded that, in mammalian cardiac muscle, the lumens of the longitudinal tubules are continuous with the lumens of the T tubules, forming an extensively interconnected T-L tubular system. Hence, every myofibril has close access to a fluid-filled space which is continuous with the interstitial fluid and which may be of similar cationic composition; such an arrangement should facilitate excitation-contraction coupling.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1432-0878
    Keywords: Muscle ultrastructure ; (Na+, K+)-ATPase localization ; Sarcotubules ; Sarcoplasmic reticulum ; Junctional SR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary ATPase activity sensitive to ouabain was examined in both cardiac (ventricular) and skeletal (tibialis anterior) muscle cells of the mouse. Short-term fixation was combined with incubation in a medium designed to reduce artifactual deposition of lead phosphate. With incubation medium containing Na+ and K+, Pb3 (PO4)2 precipitate appears throughout the sarcoplasmic reticulum (SR) of both cardiac and skeletal cells. The precipitate generally is heavier in the junctional SR than in network SR, although the two regions are interconnected. Ouabain (1 mM) eliminates activity in the network SR of myocardial cells, but only reduces it in skeletal muscle cells. The total ATPase activity of junctional cisternae of the SR of myocardial cells does not appear to be reduced by ouabain, whereas the activity of the terminal cisternae of skeletal muscle is substantially diminished. The use of an incubation medium containing zero K+ reduces the level of activity, but not consistently. These data suggest that (Na+, K+)-ATPase is present in the network SR of both cardiac and skeletal muscle cells, and probably in the terminal cisternae of skeletal muscle cells.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1573-4919
    Keywords: slow (L-type) Ca++ channels ; Ca++ currents ; myocardial cells ; phosphorylation ; ATP regulation ; developmental changes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Contraction of the heart is regulated by a number of mechanisms, such as neurotransmitters, hormones, autacoids, pH, intracellular ATP, and Ca++ ions. These actions are mediated, at least in part, by actions on the sarcolemmal slow (L-type) Ca++ channels, exerted directly or indirectly. The major mechanisms for the regulation of the slow Ca++ channels of myocardial cells includes the following. cAMP/PK-A phosphorylation stimulates the slow Ca` channel activity, whereas cGMP/PK-G phosphorylation inhibits. DAG/PK-C phosphorylation and tyrosine kinase phosphorylation are suggested to stimulate the slow Ca++ channel activity. Intracellular application of Gsα protein increases the slow Ca++ currents (ICa(L)). Lowering of intracellular ATP inhibits ICa(L). Acidosis and increase in [Ca]i inhibits ICa(L). A number of changes in the Ca++ channels also occur during development and aging. Thus, it appears that the slow Ca++ channel is a complex structure, including perhaps several associated regulatory proteins, which can be regulated by a number of extrinsic and intrinsic factors, and thereby control can be exercised over the force of contraction of the heart.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1573-4919
    Keywords: heart cells ; aortic cells ; Ca2- current ; K+ current ; slow Na+ current ; Angiotensin II ; calcium blockers ; potassium blockers ; patch clamp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Summary The whole-cell voltage clamp technique was used to study the slow inward currents and K+ outward currents in single heart cells of embryonic chick and in rabbit aortic cells. In single heart cells of 3-day-old chick embryo three types of slow inward Na+ currents were found. The kinetics and the pharmacology of the slow INa, were different from those of the slow Ica in older embryos. Two types of slow inward currents were found in aortic single cells of rabbit; angiotensin 11 increased the sustained type and d-cAMP and d-cGMP decreased the slow transient component. Two types of outward K+ currents were found in both aortic and heart cells. Single channel analysis demonstrated the presence of a high single K+ channel conductance in aortic cells. In cardiac and vascular smooth muscles, slow inward currents do share some pharmacological properties, although the regulation of these channels by cyclic nucleotides and several drugs seems to be different.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1573-4919
    Keywords: heart cells ; smooth muscle Bay K 8644 ; K+ current ; patch clamp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Summary The effects of the Ca2+ agonist Bay K 8644 on outward potassium currents have been studied in single ventricular cells of chick embryo and aortic single cells of rabbit using the whole-cell patch clamp technique. Bay K 8644 was found to increase lK in both heart and aortic single cells. This effect of Bay K 8644 on both muscle was reversed by Mn2+ and blocked by 20 mM TEA. The Bay K 8644 potassium I/V curve of single heart cell had a N shape, which is Ca2+ dependent. These data strongly suggest that Bay K 8644 increases a gK(ca) in both aortic and heart muscle.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 200 (1979), S. 367-382 
    ISSN: 1432-0878
    Keywords: Ruthenium red ; Skeletal muscle ; Cardiac muscle ; Membrane permeability ; Sarcoplasmic reticulum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effects of ruthenium red (RR) on amphibian and mammalian skeletal muscles and mammalian myocardium were examined. In skeletal muscle cells, a discrete pattern of staining can be brought about within the lumina of the terminal cisternae (junctional sarcoplasmic reticulum [SR]) by sequential exposure to RR and OsO4. After prolonged immersion in RR solution, formation of pentalaminar segments (“zippering”) occurs at various points along the longitudinal (“network”) SR tubules. Zippering can be elicited in skeletal SR at any stage of preparation prior to postfixation with OsO4. By means of dispersive X-ray analysis, both ruthenium and osmium were seen to be deposited in skeletal muscle junctional SR, and ruthenium was detected in the myoplasm as well. In skeletal muscles whose T tubules were ruptured by exposure to glycerol, the pattern of SR staining and zippering resulting from ruthenium-osmium treatment was not affected. These findings indicate that RR is capable of passage across the sarcolemma of skeletal muscle and that this passage does not occur solely under conditions in which the plasma membrane is damaged. In contrast, RR does not opacify or modify any region of the SR of cardiac muscle. However, after this treatment, randomly distributed opaque bodies, composed of parallel lamellar structures, appear throughout the myocardial cells. A few of these bodies are associated with lipid droplets, but the rest are of unknown origin. The failure of the SR of cardiac muscle to stain after exposure to ruthenium dye (even though this material enters these cells) suggests that the chemical composition of cardiac SR is significantly different from that of skeletal muscle SR.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1432-0878
    Keywords: Embryonic development ; Ventricular myocardium ; Transverse and axial tubules ; Guinea pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Developing transverse (T) tubules are found in embryonic guinea pig ventricular myocardium after approximately eight weeks of gestation. By the time of birth (nine weeks total gestation), longitudinally-oriented axial tubules connected to the T tubules also have formed, and the majority of cells closely resemble those of the adult. The form taken by the developing T and axial tubules suggests that they are generated in a manner similar to that for T tubules in chick and rat skeletal muscle, namely by repeated formation of caveolae.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 0005-2736
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    ISSN: 0005-2760
    Keywords: (Rat aorta muscle cell) ; Ca^2^+ ; Phospholipase A"2
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...