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At least 919 records · Page 51Linked to original sources
PubMed1996

Internalization of anti-nucleolin antibody into viable HEp-2 cells.

Anti-nucleolin antibodies have been detected in patients with systemic connective tissue diseases (SCTD) including systemic sclerosis (SSc) and systemic lupus erythematosus (SLE). In vivo bound autoantibodies to nucleoli of epidermal keratinocytes have been demonstrated in skin from patients with SCTD. In this study, monoclonal antibody to nucleolin (D-3) was used to determine the distribution of nucleolin in different culture cells including HEp-2, HepG2, HRCC, Molt-4 and Wil2 cells. Nucleolin was found to be present on the surface of HEp-2 and HepG2 cells, but not on the surface of HRCC and lymphoblastoid (Molt-4 and Wil2) cells; in contrast, nucleolin was detected in the nucleoli of all permeabilized cells examined. In immunoprecipitation, using extracts from 32P-labeled HEp-2 cells as antigenic source, cell membrane as well as nuclear nucleolins were found to be phosphorylated with a molecular weight of 105 kDa. Viable HEp-2 and HepG2 cells were cocultured with IgG fraction of D-3 in a CO2 incubator for 1 to 24 h, and then permeabilized with acetone followed by immunofluorescence staining with FITC-labeled goat anti-mouse IgG antibodies. Nucleolar staining was observed in cells after 10 h or longer of coculture. These data indicated that D-3 antibody reacted with cell membrane nucleolin and subsequently gain access into cells in a process related to pinocytosis.

Cell Line↗
PubMed1991

Active transport of polypeptides in rabbit nasal mucosa: possible role in the sampling of potential antigens.

Transepithelial pathways of macromolecule transport have been studied in vitro in rabbit nasal respiratory mucosa, maintained at 27 degrees C. Transepithelial electrical potential difference, short-circuit current and resistance were 3.4 +/- 0.5 mV (submucosa positive), 65.0 +/- 6.7 microA cm-2 and 52.1 +/- 5.6 omega cm-2 respectively (n = 15). These electrical characteristics are those of a leaky epithelium allowing macromolecules to permeate paracellularly. A detailed permeation study of a polypeptide (elcatonin, Mw = 3362) was also undertaken. Elcatonin mucosa-submucosa (Jms) and submucosa-mucosa (Jsm) fluxes were measured by radioimmunoassay. With 10 micrograms/ml elcatonin, Jms was significantly larger than Jsm for the whole 120-min period of observation; net flux showed a maximum in the first 30 min (Jms = 13.6 +/- 1.0 ng cm-2 h-1, Jsm = 1.4 +/- 0.1 ng cm-2 h-1, n = 10). Jms fell towards the value of Jsm if the temperature was reduced to 4 degrees C or if the mucosa was simultaneously treated with 0.1 mM dinitrophenol and 3 mM monoiodoacetate. Jms and Jnet followed saturation kinetics with increasing elcatonin concentrations. Adrenocorticotropic hormone (Mr = 4500) produced a similar pattern to elcatonin. However, Jms and Jsm were not significantly different from each other at any time either for [3H]sucrose (Mw = 342) or for [14C]polyethyleneglycol-4000 (Mw = 4000) when present in the bathing medium at 500 microM concentration. The results show active transport of polypeptides in parallel with passive permeation (possibly through leaky intercellular junctions). Active transport does not appear to be related to nonspecific pinocytosis but to receptor-mediated endocytosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenocorticotropic Hormone↗
PubMed1992

Morphogenesis of the photoreceptor outer segment during postnatal development in the mouse (BALB/c) retina.

Disc formation of rod photoreceptor cells in developing BALB/c mice retinas was studied by rapid freeze, freeze-substitution, freeze-etching, immunocytochemistry, and myosin S-1 decoration methods. Freeze-substituted photoreceptor cells contained variously shaped vesicles in the apical swelling of the connecting cilium or the base of the outer segment during postnatal development. Rapid freezing successfully arrested pinocytosis; the fusion of small vesicles to give large ones, and the compression of certain vesicles (0.3-0.6 micron) appears to lead gradually to the formation of the so-called discs. We therefore propose that membranous discs are formed by the fusion of small pinocytotic vesicles and their subsequent compression. Discs formed in this way were partially stacked, but were ordered at random during the early developmental stages. During development, a partial stack of discs was progressively rearranged to a regular form as seen in mature outer segments. Cytoskeletal actin was expected to be involved in the disc formation; it was demonstrated in the distal axoneme of the connecting cilium during development and showed no change in its distribution. However, the polarity of the actin filaments, as revealed by myosin S-1 decoration in early developmental stages, was much more variable than in the adult. Barbed ends of actin filaments were associated with the plasma membrane or the membrane of vesicles. We also found actin filaments coiled up helically on ciliary microtubules.

Actins↗
PubMed1978

Electron microscopy observations on Trypanosoma brucei: freeze-cleaving and thin-sectioning study of the apical part of the flagellar pocket.

Observations on the apical part of the flagellar pocket of Trypanosoma brucei using the freeze-cleaving and thin-sectioning techniques of electron microscopy are reported. The flagellar pocket is shown as a flask-shaped depression in the body, continuous with the pellicle and flagellar sheath. The membranes of the apical part of the pocket on the flanged side of the body compress the flagellar sheath, forming part of a "neck region". This region is completed on the broad body side of the flagellar pocket when it embraces the flagellar sheath. The possible role of the neck region in the dynamic function of pinocytosis is discussed.

Animals↗
PubMed1976

Myxoid liposarcoma. Light and electron microscopic investigation.

Liposarcoma is an important soft tissue sarcoma. It requires careful classification into types, since prognosis varies considerably with histological appearance. In this case a myxoid sarcoma is shown to contain cells resembling fetal fat with active pinocytosis, and some scanty signet-ring cells. Their ultrastructural appearances are described.

Adult↗
PubMed1976

[Sturcture and function of the mononuclear phagocytic system (MPS) in chronic rhinosinusitis. A light and electron microscopic investigation (author's transl)].

Neither the concept of the Reticulo-Endothelial-System (RES) Aschoff's (1924) nor that of the Reticulo-Histiocyte-System (RHS) provides a satisfactory framework into which the present knowledge of the phagocytic mononuclear cells can be fitted. Current knowledge concerning morphology, histochemistry (peroxydase and esterase activity), immunology (specific surface antigens, receptors on the cell membranes), function (immune phagocytosis, pinocytosis), kinetics (3H-thymidine labelling) and culture makes it possible to place all highly phagocytic mononuclear cells and their precursors in one system, which is called the Mononuclear-Phagocytic-System (MPS) (Langevoort, Cohn, Hirsch, Humphrey, Spector, van Furth, 1969). Kinetic studies with labelled cells have shown, that mononuclear phagocytes originate from precursor cells in the bone marrow (stem cell leads to monoblasts leads to promonocytes), than are circulating in the peripheral blood as monocytes and are transformed to tissue macrophages entering tissues. The MPS comprises following cells in following organs: connective tissue (histiocytes resp. macrophages); liver (Kupffer-cells); lung (alveolar macrophages); lymph nodes (free and fixed macrophages); bone marrow (macrophages); serous cavities (pleural and peritoneal macrophages); bone tissue (osteoclasts?); nervous system (microglial cells) (SEE Table 1). The reticular cells, endothelial cells and fibroblasts (fibrocytes) can therefore not be included in the MPS. Besides differences in morphology, histochemistry and function, they derive from mesenchymal cells and not from the bone marrow as the MPS. The present investigation demonstrates the structure and significance of the MPS in various kinds of chronic-specific and non-specific rhinosinusitis. On semithin sections two kinds of macrophages can be distinguished light-microscopically: 1. Larger macrophages with many phagosomes (storage cells) (Fig. 1A), which can exhibit sometimes a ring-shape on sections embracing greater parts of the interstitium (Fig. 1B). Such forms are mainly found in chronic (maxillary) sinusitis and are interpretated as "scavenger" macrophages. 2. The second type consists of smaller macrophages with extremely ruffling of the cell surface, which is interpretated as an expression of highly (specific?) stimulated states. These later macrophages can be seen mainly in edematous nasal polyps, which might be caused by allergic reactions of the anaphylactic type. The fine structure of the phagocytes is to some extent dependent on the actual development and functional state: there are "immature" macrophages, which are practically indistinguishable from blood monocytes (Fig. 2A); some of them can be stimulated and can therefore show many surface foldings and projections (Fig. 2B). The "mature" macrophage shows a well developed Golgi-area and many secondary lysosomes (Fig. 3). The storage type of the macrophages, which can predominate in some cases of chronic maxillary sinusitis, is characterized by many electron-lucent vacuoles (Fig. 4)...

Chronic Disease↗
PubMed1984

Absorption of elastase through the jejunal mucosa of the rat. An immunocytochemical study.

In order to reveal the absorption process of elastase from the intestine, hog pancreatic elastase was injected into the ligated jejunum lumen of the rat, and the tissues were cytochemically observed at various times after injection. The peroxidase anti-peroxidase (PAP) method using anti-hog-elastase rabbit antibody was used for light microscopy, and the anti-elastase Fab'-peroxidase conjugate was used for electron microscopy. The tissues stained by the PAP method exhibited a dense deposition of reaction products on the luminal surface of epithelial cells and a moderate deposition in the blood and lymph capillaries of the intestinal villi. Immunoelectron microscopy revealed that the reaction product was deposited on the surface of the microvilli and in their pocketing; some was found in the pinocytotic vesicles in the terminal-web area and on the inner surface of the enlarged smooth endoplasmic reticulum. Round droplets which gave a positive reaction were found in the widened intercellular cleft and the thick basement membrane lining the blood capillaries and lymphatics. The jejunum retained its normal ultrastructure. The results indicate that the elastase molecules, which were introduced into the rat jejunum lumen, were absorbed without being decomposed through healthy intestinal epithelial cells by pinocytosis and translocated into blood and lymph capillaries.

Animals↗
PubMed1984

Coexistence of renin and angiotensin II in epitheloid cell secretory granules of rat kidney.

The distribution of renin and angiotensin II (ANG II) in juxtaglomerular epitheloid cells of control and adrenalectomized rats was studied, using specific antisera and the protein A-gold technique in Lowicryl- and glycol methacrylate-embedded tissue. The matrix of virtually all mature secretory granules of epitheloid cells contains not only renin, but also ANG II. On adrenalectomy, the concentration of both renin and On adrenalectomy, the concentration of both renin and ANG II in the granule internum increases markedly, as indicated by the density of the immunolabel. Given the coexistence of renin and ANG II in the granule matrix, it is quite probable that, with each secretory event, a certain amount of ANG II is released together with renin. Further experiments will have to show if this amount of ANG II cosecreted with renin is sufficient to elicit immediate local intrarenal actions. ANG I, as well as angiotensinogen and converting enzyme, were not found in epitheloid cells. It is therefore inferred that ANG II is not generated intracellularly, but within the extracellular space and subsequently taken up by pinocytosis and incorporated into the secretory granules of epitheloid cells.

Adrenalectomy↗
PubMed1977

Interaction of tetanus toxin and toxoid with cultured neuroblastoma cells. Analysis by immunofluorescence.

The primary interaction of tetanus toxin and toxoid with mouse neuroblastoma cells (C 1300, clone NB2A) in tissue culture was studied using direct immunofluorescence. Experiments were done in standard routine cultures and also those influenced by chemical modulators. There is a difference in the characteristic binding response between the growth culture cells (grown in presence of fetal calf serum) and differentiating culture cells (grown in absence of serum). Exposure to the toxin gives no visible effect on the cell division or viability in growth cultures; whereas in differentiating cells the processes are shortened and the adherence to the glass is diminished without involving significant cell death. The toxoid did not bind at all under the same experimental conditions. Since there was no biological effect in growth cultures we have called this binding ineffective, and in the case of the differentiating cells, effective binding. Stimulation of pinocytosis increases the uptake of toxin in both cultures. Presence of some surface bound toxin still remaining on the differentiating cells indicates the possibility of another sort of mechanism for internalization. Pre-treatment of the cells with neuraminidase or beta-galactosidase to alter the membrane gangliosides eliminates binding in growth cultures but not in differentiating cultures. From these results we suggest that even though the toxin may well bind to gangliosides, at least in the differentiating cultures they are not solely responsible for the fixation. The morphologically observed effective binding is probably that not related to gangliosides.

Binding Sites↗
PubMed1987

Cerebrovascular permeability to horseradish peroxidase in hypertensive rats: effects of unilateral locus ceruleus lesion.

Unilateral locus ceruleus lesion enhances leakage of radioiodinated human serum albumin into the ipsilateral cerebral cortex of rats with norepinephrine-induced hypertension. This ultrastructural study was undertaken, to determine the mechanism by which this permeability alteration occurs, using horseradish peroxidase (HRP) as a tracer. Unilateral locus ceruleus lesion was produced in male Wistar-Furth rats by stereotaxic microinfusion of 5 micrograms of 6-hydroxydopamine. Two weeks later, rats were injected with HRP intravenously and acute hypertension was induced in awake rats by an intravenous infusion of norepinephrine (6 micrograms), epinephrine (6 micrograms) or angiotensin amide (12 micrograms) given over a 2-min period. Thirty seconds later, the rats were perfused with fixative under deep anesthesia and their brains were sliced and processed for demonstration of HRP reaction product. Leakage of HRP occurred in both cerebral hemispheres in response to hypertension induced by the three pressor agents, but the leakage was greater on the lesioned side in response to epinephrine and norepinephrine, while in the case of angiotensin-induced hypertension side-to-side differences in permeability alterations were not observed. In both cerebral hemispheres increased permeability affected mainly arterioles, which showed enhanced pinocytosis as the principal mechanism of HRP extravasation.

Animals↗
PubMed1985

Growth hormone effect on accumulation of arterial basement membrane-like material studied on rabbit aortic myomedial cell cultures.

The effect of human growth hormone on arterial basement membrane-like (BM) material was studied. BM-like material was obtained from the cell layer of cultured aortic myomedial cells using a sonication-differential centrifugation technique. After the addition of small amounts of growth hormone (1 ng/ml) to the cultures, we observed a 26% increased incorporation of amino acids into BM-like material (2p less than 0.005). However, further increase in the incorporation was not observed using either 3 ng or 10 ng growth hormone per ml. Growth hormone inhibited removal/degradation of BM-like material by 16% (2p less than 0.01). However, pinocytosis rate and activity of major lysosomal enzymes: cathepsin D, acid phosphatase and beta-N-acetyl-glucosaminidase were unchanged. Incorporation of glycosaminoglycans as evaluated by [35SO4]-labelling was reduced by 8% when cells were exposed to growth hormone (2p less than 0.01). The present study demonstrates an effect of growth hormone on the turnover and composition of BM-like material in cultured arterial myomedial cells.

Amino Acids↗
PubMed1989

Effect of blood meal and mating on the genital tract ultrastructure in the female camel tick Hyalomma (Hyalomma) dromedarii (Ixodoidea: Ixodidae).

The genital tract ultrastructure in the female Hyalomma (Hyalomma) dromedarii is described during feeding and mating and up to oviposition. The vagina, consisting of vestibular (VV) and cervical (CV) regions, is formed of an epithelium lined internally with a folded cuticular layer and surrounded externally by muscle layers. These facilitate the passage of endospermatophores containing sperm into the receptaculum seminis (RS), and ova to the exterior. A pair of tubular accessory glands (AG) opening at the junction of VV and CV consist of an epithelial layer of undifferentiated cells. As feeding progresses, these cells synthesise their granular secretion which lubricates the egg surface during its passage through VV. The RS, opening anteriorly into the CV, consists of cuboidal cells lined with a thin cuticular layer. These cells become rich in glycogen and lipid vacuoles, possibly acting as a source of energy for various cell activities including granule synthesis and exocytosis. The granules discharge their contents into intercellular spaces distributed throughout the RS wall and communicate with the main lumen via narrow channels. The cell secretion may dissolve the endospermatophore wall to release sperm, while their lysosome-like structures may function in the breakdown of endospermatophoric material taken up by pinocytosis. The connecting tube (CT) opens into the CV anterodorsally and leads into the common oviduct (COV) posteriorly. It consists of an epithelium lined by a closely-adhering cuticular layer, giving the tube lumen the appearance of an undulate labyrinth with a complicated configuration. No secretory activity in the CT has been observed before, during, or after feeding. The paired, non-cuticular oviducts, extending from the ovary and fusing anteriorly to form COV, consist of an epithelium poor in cell organelles. At the final stages of feeding the cell cytoplasm contains large, phagosomal vacuoles penetrated by sperms, in addition to micropinocytotic vesicles which serve to break down the seminal fluid and other materials. The basal membrane is infolded giving characteristic features, which increase dramatically during oviposition, of epithelia involved in ion and water transport. The oviducal secretion may function as a tanning agent to harden the egg-shell and may also act as a lubricant for egg passage.

Animals↗
PubMed1985

Two modes of human rotavirus entry into MA 104 cells.

Entry of the KUN strain of human rotavirus into MA 104 cells was studied by electron microscopy. Virus particles attached to the cell membrane appeared to be almost exclusively double-shelled virions. These attached virions followed two distinct pathways into the cytoplasm depending on pretreatment with trypsin. Using infectious rotavirus which had been pretreated with trypsin, the viral nucleoids passed directly into the cytoplasm within 5 minutes after inoculation, through dissolution of the viral capsid and cell membrane. Using non-infectious rotavirus that had not been pretreated with trypsin, phagocytosis or pinocytosis occurred in which virions were sequestered into lysosomes 20 minutes after virus attachment to the cell membrane. After being sequestered, uncoating of the rotavirus virions within lysosomes was seen, but it did not result in release of the genome. On the basis of these observations it was concluded that when virions were pretreated with trypsin, virus replication occurred following the direct passage of viral nucleoids into the cell cytoplasm. However, mere phagocytosis of virus particles into cell lysosomes, which occurred when trypsin-untreated virus was used, does not appear to be related to rotavirus replication.

Adhesiveness↗
PubMed1993

A transmission and scanning electron microscopic study of tumoral and peritumoral microblood vessels in human gliomas.

The tumor microblood vessels (MBVs) of 25 cases of gliomas of varying grades were studied and compared with those in peritumoral region using both transmission and scanning electron microscopy (TEM and SEM). The TEM study revealed numerous villous projections with pinocytotic vesicles (PCVs) and large vacuoles (LVs) concentrated mainly at the luminal aspect in tumor MBVs which increased with increasing severity of edema. The peritumoral MBVs, in addition to showing some increase in villous projections on the luminal surface, also showed increased number of PCVs and LVs concentrated at the abluminal aspect with some of them even communicating with the extravascular space. The SEM study largely corroborated the TEM findings. The sites of formation of PCVs and LVs appeared as small pits or large craters on the luminal surface of the endothelial cells of tumor MBVs. We feel that the morphological evidence of increased permeability in tumor MBVs represents their role in the development of edema and that the occurrence of reverse pinocytosis in peritumoral MBVs is a distinct possibility which may be associated with resorption of edema fluid.

Astrocytoma↗
PubMed1985

The pathogenetic and prognostic significance of blood-brain barrier damage at the acute stage of aneurysmal subarachnoid haemorrhage. Clinical and experimental studies.

In a retrospective study, pathological tissue enhancement was found in nearly two fifths of patients with acute SAH on contrast-enhanced cranial computed tomography. By means of absorption measurements with the region of interest technique over the basal ganglia, it was proved indirectly that pathological tissue enhancement should be brought about not only by hyperaemia, i.e., a blood volume increase, but also by extravasation of the contrast material, i.e., blood-brain barrier (BBB) disruption. A similar conclusion was drawn from the retrospective isotope brain scintigraphy study. It was further established that, although the pathological contrast enhancement was most obvious in the cortex, and particularly in the neighbourhood of the subarachnoid spaces, the phenomenon is probably widespread throughout the brain. Patients with abnormal enhancement are likely to be in less favourable clinical grades, have a high incidence of marked or diffuse spasm, have a poorer outcome independent of surgical or conservative treatment, and develop cerebral infarction more frequently. Systemic arterial hypertension was associated with an increased incidence of abnormal enhancement. Pathological tissue contrast enhancement or isotope accumulation in the first few days of SAH may serve as prognostic signs indicative of the late development of vasospasm and ischaemia. As ischaemic disruption of the capillary system is not prominent in the initial days following any stroke, vasoactive substances arising from the breakdown of the blood clot should play important part in the BBB damage in the acute stage of SAH. The "cortical SAH" model developed in the animal experiments ensured a constant subarachnoid blood volume with minimal local brain damage. The intracranial pressure and mean arterial blood pressure did not change significantly, and perfusion defects did not arise. Thus, this model proved suitable for studying the influence on the BBB of vasoactive blood breakdown products (responsible for arterial spasm) without the accompanying effects of pathological conditions such as raised intracranial pressure, systemic hypertension, non-reflow phenomena, which also disrupt the BBB. Measurements on the water, electrolyte, albumin contents of brain tissue, as well as the immunohistochemical localization of albumin, clearly indicated that the brain oedema developing at the acute stage of experimental SAH could be classified as having a primary vasogenic component in addition to the cytotoxic component. This increased capillary permeability was found to be brought about by opening of tight junctions and pinocytosis in the endothelial cells. The pathological capillary permeabilit

Adolescent↗
PubMed1986

Proton transport and membrane shuttling in turtle bladder epithelium.

Proton secretion in the urinary bladder of the fresh-water turtle is mediated by proton pumps located in the apical membrane of carbonic-anhydrase (CA)-rich cells. It has been proposed that the rate of proton transport is regulated by endocytotic and exocytotic fusion processes which alter the apical membrane area, and hence number of exposed pumps. Three techniques were used to study this process. Analyses of transepithelial impedance provided estimates of transport-associated changes in net membrane area, as well as other electrical parameters. Electron microscopy allowed visualization of the endocytotic vesicles thought to be involved in the process. Finally, uptake of a fluorescent fluid-phase marker provided measurements of the rates of endocytosis. We report the following: endocytotic and exocytotic processes occur primarily in the CA-rich cells; inhibition of proton transport resulting from 0.5 mM acetazolamide (AZ) results in a decrease in the apical membrane area of approximately 0.47 cm2/cm2 tissue; the apical membrane specific conductance of the CA-rich cells is approximately 220 microS/microF, and possibly represents a Cl- conductance that may function in counter-ion flow; the decline in transport following AZ is not directly proportional to the decline in apical membrane area, suggesting that changes in pump kinetics are also involved in the regulation of transport; the CA-rich cells exhibit a high rate of constitutive pinocytosis, and hence membrane shuttling, which appears to be independent of the rate of transport; AZ induces a transient increase in the rates of endocytosis and shuttling; and the transport-associated changes in apical membrane area may reflect an effect of AZ on a regulated endocytotic pathway which is distinct from the pinocytotic process.

Animals↗
PubMed1988

Constitutive and transport-related endocytotic pathways in turtle bladder epithelium.

Proton secretion in the urinary bladder of the freshwater turtle is mediated by a proton pump located in the apical membrane of a population of cells characteristically rich in carbonic anhydrase. Earlier studies have demonstrated that these cells exhibit apical-membrane endocytotic and exocytotic processes which are thought to be involved in the regulation of the rate of proton transport via alterations in the number of pumps within the apical membrane. In this study, we sought to characterize these processes using two different methods. Analysis of transepithelial impedance yielded estimates of membrane capacitance which could be related to membrane area, thereby allowing one to monitor net changes in apical-membrane area resulting from changes in the net rates of endo- and exocytosis. Uptake of the fluid-phase marker FITC-dextran provided a measure of net extracellular volume uptake which was related to net rates of endocytosis. Our major conclusions are summarized as follows. The bladder cells exhibit a high baseline rate of endocytosis which appears to be a constitutive process similar to pinocytosis. This process is completely inhibited when ambient temperature is reduced to 15 degrees C. In addition, serosal application of 0.5 mM acetazolamide causes a transient increase in the rate of endocytosis, concomitant with a decrease in the rate of transport. Reduction of ambient temperature to 15 degrees C reduces the rate of acetazolamide-induced endocytosis, but does not abolish it. Addition of 1 mM serosal azide not only prevents the acetazolamide-induced increase in endocytosis, but also prevents the decrease in transport caused by acetazolamide. Azide has no effect on the baseline rate of endocytosis, nor does it prevent inhibition of carbonic anhydrase by acetazolamide. The specificity of azide, coupled with the different temperature sensitivities, demonstrate that the constitutive and transport-dependent endocytotic pathways are distinct processes. The observation that azide prevents both the acetazolamide-induced increase in endocytosis and the decrease in transport strongly supports the notion that endocytosis of proton-pump-containing membrane is requisite for the inhibition of transport by acetazolamide. Finally, the results also demonstrate that acetazolamide does not inhibit proton secretion simply by inhibiting carbonic anhydrase.

Acetazolamide↗
PubMed1994

Shear-dependence of endothelial functions.

Endothelial cells are subjected to shear forces which influence important cell functions. Shear stress induces cell elongation and formation of stress fibers, increases permeability, pinocytosis and lipoprotein internalization, is involved in the formation of atherosclerotic lesions, increases the production of tissue plasminogen activator, and enhances von Willebrand factor release and hence platelet aggregation. It decreases adherence of erythrocytes and leukocytes, and increases the release of prostacyclin, endothelium derived relaxing factor, histamine and other compounds, but decreases erythropoietin secretion. The mechanism of signal transduction to the endothelial cell is not known exactly; shear-sensitive ion channels seem to be involved. It is concluded that a better understanding of shear-dependent endothelial functions will influence pathophysiologic concepts and therapeutic interventions.

Animals↗