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  • 1
    Electronic Resource
    Electronic Resource
    Shear stress-induced upregulation of connexin 43 expression in endothelial cells on upstream surfaces of rat cardiac valves (2000)
    Springer
    Histochemistry and cell biology 122 (2000), S. 477-483 
    Details
    ISSN: 1432-119X
    Keywords: Connexin ; Endothelial cell ; Cardiac valve ; Shear stress ; Size
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: AbstractEndothelial expression of the gap junction proteins, connexin (Cx) 37, Cx40, and Cx43, varies within the vascular network. While previous studies suggest that shear stress may upregulate Cx43, it is not well understood if shear stress affects the expression of all endothelial connexins and to what extent. Endothelial cells on the upstream and downstream surfaces of cardiac valves are subjected to considerably different intensities of shear stress. We therefore reasoned that we could determine the extent hemodynamic forces affect the expression of Cx37, Cx40, and Cx43 by comparing their immunohistochemical distribution on the upstream and downstream surfaces of rat cardiac valves. We found 70- to 200-fold greater expression of Cx43 in the endothelial cells on the upstream than on the downstream surfaces. However, Cx37 was expressed almost equally in the endothelial cells on upstream and downstream surfaces, and Cx40, a major connexin in most vascular endothelial cells, was not detected on either surface. In addition to the heterogeneity in Cx43 expression, endothelial cells on the upstream surface were 35% to 65% smaller than those on the corresponding downstream surface. These results suggest that shear stress may affect endothelial cell size and Cx43 expression but not Cx37 expression.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00418-004-0717-6
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  • 2
    Electronic Resource
    Electronic Resource
    Connexin 43 and the glucose transporter, GLUT1, in the ciliary body of the rat (1996)
    Springer
    Histochemistry and cell biology 106 (1996), S. 209-214 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  To investigate the relationship between the gap junction protein connexin 43 and the glucose transporter GLUT1, their localization was visualized by double-immunofluorescence microscopy using frozen sections as well as immunogold staining of ultrathin frozen sections. In pigmented epithelial cells, most of the GLUT1 was localized along the plasma membrane facing the blood vessels, whereas in non-pigmented epithelial cells, it was present along the plasma membrane facing the aqueous humor. Connexin 43 was abundant in the ciliary body and localized mainly in the gap junctions connecting the pigmented and non-pigmented epithelial cells. Localization of GLUT1 and connexin 43 in the blood-aqueous barrier suggests that GLUT1, connexin 43, and GLUT1 disposed in this order could be a machinery responsible for the transport of glucose across the blood-aqueous barrier.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004180050033
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  • 3
    Electronic Resource
    Electronic Resource
    Immunolocalization of GLUT1 and connexin 26 in the rat placenta (1996)
    Springer
    Cell & tissue research 285 (1996), S. 83-89 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Glucose transporter ; GLUT1 ; Connexin 26 ; Gap junctions ; Placenta ; Syncytiotrophoblast ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Interhemal membrane in the rat placenta is composed of three trophoblastic layers and endothelial cells. GLUT1, an isoform of the facilitated-diffusion glucose transporter, is abundant in the cells of the placental barrier, i.e., syncytiotrophoblastic layers I and II. GLUT1 is localized at the plasma membranes of the maternal-blood side of syncytiotrophoblastic layer I, and of the fetal-blood side of syncytiotrophoblastic layer II. Double-immunofluorescence microscopy has shown that connexin 26 is present between these GLUT1-positive sites, i.e., between syncytiotrophoblastic layers I and II. Immunogold electron microscopy has revealed that connexin 26 is localized in the gap junctions connecting the two layers. Connexin 26 in these layers therefore makes them functionally a single syncytial layer for the transfer of small molecules such as glucose in the rat placental barrier. These results suggest that glucose transfer in the rat placental barrier is carried out as follows: GLUT1 is used for the entry of glucose into the cytoplasm of syncytiotrophoblastic layer I, connexin 26 for the transfer of glucose from syncytiotrophoblastic layer I to syncytiotrophoblastic layer II, and GLUT1 for the exit of glucose to the fetal circulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050623
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  • 4
    Electronic Resource
    Electronic Resource
    Quick-freeze, deep-etch visualization of the ‘cytoskeletal spring’ of cochlear outer hair cells (1991)
    Springer
    Cell & tissue research 263 (1991), S. 91-97 
    Details
    ISSN: 1432-0878
    Keywords: Cytoskeleton ; Ear, middle ; Contractile apparatus ; Hair cells ; Guinea pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The lateral membrane system of the cochlear outer hair cell, consisting of the lateral plasma membrane, pillars, filamentous lattice and subsurface cisternae, is considered to be involved in the contractile movement of the isolated cochlear outer hair cell. The filamentous lattice, called the cytoskeletal spring, has been identified in the demembranated cochlear outer hair cell treated with the detergent Triton X-100. In this study, the quick-freeze, deep-etch method was applied to demonstrate the three-dimensional organization of both the filamentous and membranous structures of the lateral membrane system of cochlear outer hair cells. Treatment with saponin revealed that the inner leaflet of the lateral plasma membrane of the cochlear outer hair cell possesses more membrane particles than the outer leaflets, and that the pillars are closely associated with membrane particles in the inner leaflet of the lateral membrane. The presence of filamentous bridges between the filamentous lattice and the subsurface cisternae was also detected. We propose that the lateral membrane system in the cochlear outer hair cell may play an important role in the tuning mechanisms within the cochlea in normal hearing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00318403
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  • 5
    Electronic Resource
    Electronic Resource
    Specific localization of gap junction protein, connexin45, in the deep muscular plexus of dog and rat small intestine (1998)
    Springer
    Cell & tissue research 292 (1998), S. 487-494 
    Details
    ISSN: 1432-0878
    Keywords: Key words Connexin ; Gap junctions ; Smooth muscle ; Intestinal pacemaker ; Confocal laser scanning microscope ; Dog ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Cellular networks of pacemaker activity in intestinal movements are still a matter of debate. Because gap-junctional intercellular communication in the intestinal wall may provide important clues for understanding regulatory mechanisms of intestinal movements, we have attempted to clarify the distribution patterns of three types of gap junction proteins. Using antibodies for connexin40, connexin43, connexin45, smooth muscle actin, and vimentin, immunocytochemical observations were made with the confocal laser scanning microscope on cryosections of fresh-frozen small intestine and colon of the dog and rat. Connexin 45 was localized along the deep muscular plexus of the small intestine in both dog and rat. Double labeling studies revealed that connexin45 overlapped with vimentin –, but not actin-positive areas, indicating the fibroblast-like nature of the cells, rather than their being smooth muscle-like. Connexin43 immunoreactivity appeared along the smooth muscle cell surface in the outer circular layer of the small intestine of both animals. Connexin 40 immunoreactivity was not observed in the muscle layer other than in the wall of large blood vessels. It is suggested that connexin45-expressing cells along the deep muscular plexus of dog and rat small intestine are likely to act as a constituent of a pacemaker system, which may include a conductive system, by forming a cellular network operating via specific types of gap junctions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051077
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  • 6
    Electronic Resource
    Electronic Resource
    Fine structure and cytochemistry of specific granules in the lamprey atrium (1976)
    Springer
    Cell & tissue research 172 (1976), S. 487-501 
    Details
    ISSN: 1432-0878
    Keywords: Lamprey heart ; Atrial granules ; Chromaffin granules ; Endothelial granules ; Cytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Fine structural and cytochemical studies were performed to examine the nature of three types of specific granules found in the atrium of lamprey; specific granules of the atrial muscle cell (ASG), interstitial cell granules (ICG) and endocardial endothelial granules (ESG). Ultrastructurally, ASG and ICG appeared quite similar in size, shape and electron opacity, while ESG were much larger and less dense in opacity than the other two. None of the granules showed positive DAB reaction or acid phosphatase reaction. Only ICG revealed positive chromaffin reaction, which agreed with formaldehyde induced green fluorescence along the atrial lumen. Phosphotungstic acid at low pH stained ICG and ASG strongly positive, and ESG weakly positive. Pronase treatment in Epon sections for 24h digested ASG alone, whereas in glycol-methacrylate embedded sections, ESG were digested first, ASG were digested thoroughly after 30 min, but ICG were not digested completely after 90 min. From these results it can be concluded that the three types of specific granules have different constituents. ESG consist of protein with some polysaccharides; ASG are composed of protein carbohydrate complexes and lack catecholamines; ICG contain catecholamine as well as protein carbohydrate complexes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00220334
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  • 7
    Electronic Resource
    Electronic Resource
    The endosome-lysosome system in the absorptive cells of goldfish hindgut (1986)
    Springer
    Cell & tissue research 243 (1986), S. 449-452 
    Details
    ISSN: 1432-0878
    Keywords: Endosome ; Lysosome ; Cytoplasmic tubules ; Endocytosis ; Intestinal absorptive cells (goldfish)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The vacuolar system in the absorptive cells of the goldfish hindgut was studied by rapid freeze-substituted and cytochemical techniques. The apical cytoplasm of the absorptive cells contained two types of vacuoles: endosomes and lysosomes. The former were characterized by an absence of acid phosphatase activity, a dot-like distribution of material at the peripheral rim, the labelling of the inner surface with horseradish peroxidase (HRP), and by frequent connections to cytoplasmic tubules (CT), which were also free of acid phosphatase activity. The latter vacuole was preferentially located in the deeper cytoplasm and was characterized by the presence of acid phosphatase activity, an electron-dense interior matrix, a peripheral electron-lucent region (a halo), and by the detachment of HRP from the inner surface. Connections between CTs and these latter vacuoles were rarely seen. In the deeper cytoplasm, fusion between endosomes and lysosomes was sometimes observed. These results suggest that the vacuoles which are associated with CTs are endosomes, but not lysosomes, and that internalized materials are transported through the endosome-lysosome system to a giant food vacuole in the cell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00251064
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  • 8
    Electronic Resource
    Electronic Resource
    Distribution of endothelial vesicles in the microvasculature of skeletal muscle and brain cortex of the rat, as demonstrated by tannic acid tracer analysis (1986)
    Springer
    Cell & tissue research 246 (1986), S. 487-494 
    Details
    ISSN: 1432-0878
    Keywords: Microcirculation ; Endothelial vesicles ; Skeletal muscle ; Brain vessels ; Transendothelial transport ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ultrathin serial sectioning and labeling with tannic acid have demonstrated that most plasmalemmal vesicles of rat vascular endothelial cells are not free, but rather are conjoined in three dimensions to form racemose invaginations from the cell surfaces. To elucidate the distribution of vesicles in these microvascular endothelial cells, we have examined terminal arterioles, capillaries and post-capillary venules of rat skeletal muscle and brain cortex, using tannic acid labeling and stereological methods, and have determined the proportions of free vesicles and the vesicles of luminal and abluminal invaginations, as well as the numerical density of vesicles. In the case of capillaries, regional differences in distribution have also been studied. The ratio of free vesicles is 6–7% and is constant throughout the muscle microvasculature. The distribution (proportions and numerical densities) of vesicles in the brain and muscle microvascular endothelial cells shows regionally distinctive patterns. In rapid-frozen, freeze-substituted endothelial cells, there are almost as many fused vesicles as seen in chemically fixed cells. Therefore, aldehydes do not seem to induce membrane fusion, and the distribution of vesicles seems to be preserved by chemical fixation. The structure and function of plasmalemmal vesicles are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00215188
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  • 9
    Electronic Resource
    Electronic Resource
    Gap junctions in the cardiac muscle cells of the lamprey (1977)
    Springer
    Cell & tissue research 178 (1977), S. 477-482 
    Details
    ISSN: 1432-0878
    Keywords: Lamprey heart ; Gap junction ; Electrical coupling ; Nexus ; Freeze-fracture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Electron microscopy of both thin sections and freeze-fracture replicas has demonstrated the occurrence of gap junctions (nexuses) in the cardiac muscle cells of the lamprey. These gap junctions are identical in basic structure with those found in the mammalian heart. However, they are much smaller (less than 0.5 μ in diameter), and more irregularly distributed than the typical gap junction in the mammalian heart. These small gap junctions seem to provide a structural basis for the electrical coupling between cardiac muscle cells in the lower vertebrates. In addition, the well developed sarcoplasmic reticulum and subsurface cisternae, which contain an electron dense spheroidal cast, are frequently observed in the cardiac muscles of the lamprey.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219569
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  • 10
    Electronic Resource
    Electronic Resource
    Rapid formation of myometrial gap junctions during parturition in the unilaterally implanted rat uterus (1987)
    Springer
    Cell & tissue research 248 (1987), S. 297-303 
    Details
    ISSN: 1432-0878
    Keywords: Uterus (myometrium) ; Gap junctions ; Pregnancy ; Morphometry ; Freeze-fracturing ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In uterine smooth muscles, gap junction plaques rapidly form during the final stages of gestation. To investigate the related mechanisms, regional differences in myometrial gap junction development in rat uterus were examined quantitatively during delivery, using thin-section and freeze-fracture techniques in combination with light- and electron microscopy. Examination of implanted and nonimplanted horns in the unilaterally ligated rat bicornuate uteri, revealed no differences in the occurrence of gap junction plaques, but after 2 to 4 pups had been delivered, the contracted segments contained more gap junction plaques than did noncontracted segments examined immediately before delivery. In all segments, gap junctions were found more frequently in the circular muscle layers than in the longitudinal muscle layers. Gap junctions ranged in size from 0.002 μm2 to 0.52 μm2, but two-thirds were less than 0.1 μm2. The frequency of small gap junction plaques (less than 0.1 μm2) was higher in the noncontracted segment. These results suggest that gap junctions are dynamic structures, and that their formation is controlled not only by general hormonal factors, possibly involved in gap junction increases in the myometrium before delivery, but also by local factors, possibly related to the contraction, that may accelerate an increase in gap junction formation during delivery.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218196
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