Effect of calcium channel antagonists on calcium uptake and release by isolated rat cardiac mitochondria

The effects of calcium channel antagonists on Ca2+ uptake and Na+-induced Ca2+ release were studied in isolated rat cardiac mitochondria. Diltiazem, nitrendipine and nimodipine were more effective inhibitors of Na+-induced Ca2+ release (IC50 = 19-100 microM) than of Ca2+ uptake (IC50 = 0.2-1 mM). Nitrendipine and nimodipine had virtually identical IC50 values for inhibiting Ca2+ uptake, but nitrendipine was 3-4 times more potent than nimodipine at inhibiting Na+-induced Ca2+ release. If these calcium channel antagonists achieve intracellular concentrations in the range of 10(-5)-10(-4) M, our results suggest that calcium channel antagonists would preferentially inhibit mitochondrial calcium release more than mitochondrial calcium uptake.

Stereociliary glycocalyx and interconnections in the guinea pig vestibular organs

Stereociliary glycocalyx and interconnections in the guinea pig vestibular organs were investigated at the electron microscopic level by using the ruthenium red staining technique. This staining visualized the glycocalyx and ciliary interconnections as well as the contact zone between the sensory hair bundle and the otolithic membrane or the cupula. Glycocalyx was found over the entire length of the stereocilia and the kinocilium of the sensory cells as well as over the entire apical surface of the supporting cells, in the form of a fuzzy filamentous layer. The ciliary structures were found interconnected by different types of connections, such as between the kinocilium and the neighboring stereocilia, and connections between stereocilia. These connections all emerged from the fuzzy layer of the glycocalyx and were also stained identically by ruthenium red, and were therefore considered to be morphologically similar. In addition, the tips of the sensory hairs were firmly attached to the otolithic membrane or the cupula. These findings suggested that the glycocalyx in the cell lining serves as an anchoring structure for the mechanical coupling not only between the ciliary structures, but also between the sensory hair bundle and the otolithic membrane or cupula.

Proteoglycan distribution in the intima and media of the aortas of young and aging rabbits: an ultrastructural study

Aortas from normal healthy rabbits, approx. 3 months old, were examined by light and transmission electron microscopy. The proteoglycan of the extracellular matrix, which was stained by ruthenium red and appeared as granules by transmission electron microscopy, was quantitated morphometrically in the intima and the superficial media. The intima included areas which were thickened and which contained connective tissue, including proteoglycan, and some smooth muscle cells. In the thickened intima there was a greater proportion of extracellular space which was occupied by proteoglycan, and the proteoglycan was present in higher concentration than in the media. In the aortas of rabbits, approx. 2 years old, the extent of intimal thickening and the concentration of proteoglycan increased in the thickened intima but there was no evidence of extracellular lipid deposition. The endothelial basement membrane contained small proteoglycan granules (heparan sulphate) which decreased in concentration in older animals. It is possible that the accumulation of proteoglycan in the thickened intima increases the susceptibility of the intima to accumulate lipid following an additional stimulus, such as hyperlipaemia, in the initial stages of atherosclerosis.

Reversible plasma membrane ultrastructural changes correlated with electropermeabilization in Chinese hamster ovary cells

Chinese hamster ovary cells (CHO) grown in monolayers were permeabilized to molecules with molecular weight up to 1000 by high intensity 100 mus square wave electric field pulses. This permeability was transient and the cell viability was not affected. It was not possible for molecules with molecular weight larger than 1500 to penetrate inside the cytoplasm if lytic pulsing conditions were not used. In order to investigate the ultrastructural changes associated with this transient and limited permeabilization, cells were chemically fixed a few seconds after their pulsation and observed by electron microscopy. By scanning electron microscopy, numerous microvilli and blebs were observed almost immediately after application of the field. No other membrane changes were observed. Permeabilization of the membrane was visualized at the electron microscopic level by penetration of Ruthenium red. The appearance of osmotic pressure-dependent 'blebs' was indicative of local weakening of the plasma membrane. Most of these effects were fully reversible and disappeared within 30 min at 37 degrees C with the formation of huge polykaryons when cells were in contact before pulsing.

Parallel measurement of oxoglutarate dehydrogenase activity and matrix free Ca2+ in fura-2-loaded heart mitochondria

The entrapment of the Ca2+-sensitive fluorescence indicators fura-2 or quin2 in the matrix space of isolated heart mitochondria renders possible the direct monitoring of the matrix free Ca2+ [( Ca2+]m) [(1987) Biochem J. 248, 609-613]. In this paper the correlation between the [Ca2+]m and the in situ activity of oxoglutarate dehydrogenase (OGDH) in fura-2-loaded mitochondria is shown. At the initial value of [Ca2+]m, 64 nM, which corresponded to 0.36 nmol/mg mitochondrial Ca content, the OGDH activity was 12% of the maximal. Half-maximal and maximal activation were attained at 0.8 and 1.6 microM [Ca2+]m, respectively. The results indicate that an increase of the mitochondrial Ca content in the physiological range enhances the OGDH activity by means of elevation of [Ca2+]m.

The glycocalyx of inner ear sensory and supporting cells

The ultrastructure of the glycocalyx of the sensory and the supporting cells of guinea pig inner ear was studied using the ruthenium red staining technique. The glycocalyx was found over the entire length of the stereocilia and the kinocilium of the sensory cells as well as over the entire apical surface of the supporting cells appearing as a fuzzy filamentous layer. The mechanism of sensory hair fusion and its relationship to glycocalyx in gentamicin treated animals was also studied. The sensory hair degeneration process started with a decrease or even a loss of glycocalyx ensued by a local attachment of neighbouring sensory hairs. These findings have led to two hypotheses about the function of the glycocalyx of the sensory hairs. Firstly the glycocalyx serves as anchoring structure for the mechanical coupling between the ciliary structures so that when a single hair in the bundle is deflected, all stereocilia and kinocilium within that bundle move in unison as a group. Secondly, because of the electronegativity of its acidic groups, the glycocalyx serves to maintain, by repulsion, a distance between adjacent cilia, preventing close contact and preventing the cell membranes from fusing.

Quantitation of concanavalin A and wheat germ agglutinin binding by two strains of Trichomonas vaginalis of differing pathogenicity using gold particle-conjugated lectins

Two strains of Trichomonas vaginalis, which differed in their pathogenicity for both women and experimental animals hosts, were compared for the presence and number of concanavalin A (ConA)- and wheat germ agglutinin (WGA)-binding sites on their surface using gold lectin conjugates. Both strains showed a high affinity for ConA and WGA and a similar pattern of gold particle distribution on the surface coat. The gold marker was distributed over the cytoplasmic membrane sparsely as single particles but more often in groups, suggesting the presence of single and clustered sugar residues on the parasite surface. Statistical analysis of the level of lectin binding, expressed as the number of gold particles attached per 1 micron plasmalemma, by pathogenic and non-pathogenic strains of T. vaginalis show that these two strains do not differ in the number of ConA receptors on their surfaces. However, WGA-binding receptors were more numerous on the surface of the pathogenic than on the non-pathogenic strain. This suggests that these two strains differ in the number of N-acetyl-D-glucosamine residues on their surfaces. The lectin-gold particle conjugate technique therefore appears more sensitive than agglutination assays or the horseradish peroxidase-3,3'-diaminobenzidine method for the assessment of lectin-binding sites on the surface of T. vaginalis.

Ultrastructural study of contacts between cells of the dorsal ectoderm and chordamesoderm during gastrulation in Xenopus laevis

In gastrulae of Xenopus laevis, various morphological types of intercellular approximation occur between the dorsal ectoderm and chordamesoderm. Ruthenium red staining reveals that in some areas the glycocalyces of heterotypic cells appear to come into contact. These observations, in conjunction with the results of previous studies, suggest that cell contacts offer a possible pathway for the transmission of inductive stimuli, and that they may be important in the regionalization of the neuralized ectoderm.

Ruthenium-red-stained anionic charges of rat and mice mesothelial cells and basal lamina: the peritoneum is a negatively charged dialyzing membrane

The peritoneum has been classically considered to be an inert passive membrane. Previous studies demonstrated the presence of fixed anionic charges at the level of the peritoneal microvasculature and the subserosal interstitium. The present study describes the selective distribution of fixed anionic charges in the mesothelial cell plasmalemma and organelles as well as in the submesothelial basal lamina of rat and mice visceral, parietal and diaphragmatic peritoneum. These data support the idea that the peritoneum should be considered a negatively charged biological dialyzing membrane with selective capabilities. Therefore, transperitoneal transfer of charged solutes cannot be analyzed just on the basis of their molecular weight, size and shape.

Ultrastructural studies of bovine retinal microvascular basement membranes with the cationic dye ruthenium red

Our recent observation that the basement membranes of brain microvessels do not stain with the cationic dye ruthenium red has raised the question of whether the basement membranes of this and other vascular beds functioning as barriers between blood and neural tissues are deficient in the polyanionic macromolecules, such as glycosaminoglycans, which are responsible for the ruthenium red staining of other vascular basement membranes. We therefore attempted to produce staining in the only barrier-type microvascular basement membrane known to contain heparan sulfate. Bovine retinas were fixed by immersion in aldehyde fixatives containing ruthenium red, buffered with either 10 mM or 100 mM sodium cacodylate. We found discrete, electron-dense deposits of ruthenium red in vascular basement membranes, quite similar to those seen in vascular basement membranes of nonneural tissues after exposure to ruthenium red. These deposits were more distinct and more frequent in tissue exposed to ruthenium red-aldehyde solutions buffered with 10 mM cacodylate. They were not seen if ruthenium red was omitted from the fixative. The results demonstrate that anionic macromolecules in basement membranes of barrier-type microvessels can be stained with cationic dyes, and suggest that the failure of brain microvessels to stain with ruthenium red may be the result of a relative or total lack of polyanion in this basement membrane, or of other unique properties.

Purification and characterization of adhesive exopolysaccharides from Pseudomonas putida and Pseudomonas fluorescens

In this study, the adhesive exopolysaccharides of strains of Pseudomonas putida and P. fluorescens, both isolated from freshwater epilithic communities, were examined with regard to their chemical composition, biosynthesis, and their role in adhesion. Electron microscopy showed that both strains were enrobed in fibrous glycocalyces and that these structures were involved in attachment of the cells to a solid surface and as structural matrices in the microcolony mode of growth. In batch culture experiments most of the extracellular polysaccharide of both strains was found to be soluble in the growth medium rather than being associated with bacterial cells. Exopolysaccharide was synthesized during all phases of growth, but when growth was limited by exhaustion of the carbon source, exopolysaccharide synthesis ceased whereas exopolysaccharide synthesis continued for some time after cessation of growth in nitrogen-limited cultures. Exopolysaccharide from both strains was isolated and purified. Pseudomonas putida synthesized an exopolysaccharide composed of glucose, galactose, and pyruvate in a ratio of 1:1:1; the P. fluorescens polymer contained glucose, galactose, and pyruvate in a ratio of 1:1:0.5, respectively. Polymers from both strains were acetylated to a variable degree.

A close ultrastructural relationship between sulfated proteoglycans and AA amyloid fibrils

Two cationic reagents, Ruthenium red (RR) and Cuprolinic blue (CB), were used to assess the morphologic and structural relationship between sulfated proteoglycans and AA amyloid fibrils in amyloidotic spleen and liver, and in isolated fibril preparations. Amyloidotic tissue fixed in the presence of RR showed RR granules, measuring 15 to 25 nm in diameter, over areas of electrondense fibrils. In isolated fibril preparations, RR granules were specifically localized on amyloid fibrils. Amyloidotic tissue fixed in the presence of CB at 0.1 M and 0.7 M MgCl2 showed both granule and filamentous (50 to 90 nm in length) staining only over areas of amyloid fibrils. This same staining localization was also seen in isolated fibril preparations. The RR and CB granules and filaments, are believed to represent proteoglycan monomers with the glycosaminoglycan chains collapsed onto the protein core. The persistent CB staining at 0.7 M magnesium chloride suggested that highly sulfated proteoglycans were present. The glycosaminoglycan moiety has previously been identified as heparin/heparan sulphate. The intimate structural relationship between sulfated proteoglycans and AA amyloid fibrils, both in situ and in isolated fibril preparations, further suggests that these highly negatively charged molecules may have an important role in the pathogenesis of amyloidosis. Several pathogenetic scenarios are suggested.

Differential effects of chronic reserpine exposure on Ca2+ sequestering mechanisms in rat submandibular gland vesicles

To determine the effects of exposure to reserpine on subcellular Ca2+ transporting systems, active Ca2+ uptake was measured with and without ruthenium red in submandibular gland vesicles obtained from rats after chronic treatment with reserpine. The properties of ruthenium red-sensitive Ca2+ uptake were similar to those measured in submandibular gland vesicles from untreated rats: it was abolished by the dye, was relatively low at 1 microM Ca2+ but increased markedly at millimolar Ca2+ levels and was positively and significantly correlated with the mitochondrial membrane marker, cytochrome-C oxidase activity, in membrane subfractions obtained by differential centrifugation (r = 0.67, p = 0.0005, n = 29). On the other hand, ruthenium red-insensitive Ca2+ uptake, though stimulated at submicromolar Ca2+ concentrations, was reduced by a mean of 54% compared to preparations from untreated animals and particulate RNA content was 18% of that found in control preparations. Moreover, the distributions of ruthenium red-insensitive Ca2+ uptake and particulate RNA (which are closely correlated in vesicles from untreated rats) were not significantly related when measured in vesicles of submandibular glands from reserpine treated rats. Other membrane markers and overall membrane protein content were not significantly altered after chronic reserpine exposure. We conclude that reserpine treatment has little effect on mitochondrial Ca2+ uptake capacity but abolishes or drastically reduces the high affinity Ca2+-sequestering activity which, in submandibular gland vesicles from untreated rats, is apparently associated with the endoplasmic reticulum.

Development of the electromotor system in Torpedo marmorata: cationic staining of the electric organ

The electric organs of embryonic Torpedo marmorata have been reacted with three cationic stains to evaluate the appearance and distribution of anionic sites. Ruthenium red, alcian blue and lysozyme were used at different pHs and found to react in a time-related manner to anionic components within the interelectrocyte space. The basal lamina covering the ventral electrocyte surface possesses the greatest number of anionic sites whereas growth cone, presynaptic terminal and glial membranes displayed almost no staining. Since this lamina serves as the exclusive substrate for ingrowing neurites during synaptogenesis, the results are consistent with the idea that charge distribution on the membrane surface may provide a necessary cue for neurite motility, extension and eventual synaptogenesis.

Ultrastructural, histochemical, and freeze-fracture evaluation of multilamellated structures in human pulmonary alveolar proteinosis

Ultrastructural, histochemical, and freeze-fracture studies of material recovered by bronchoalveolar lavage from patients with pulmonary alveolar proteinosis revealed four types (A, B, C, and D) of multilamellated structures (MS). Type A, the major component, consisted of concentric, trilaminar structures which were composed of two electron-dense layers and a central lucent layer (5.7-7.5 nm in overall width) alternating with wider (25-30 nm) electron-lucent intervening layers. Type B MS were formed by concentric lamellae with a 5-5.3-nm periodicity. Type C MS were composed of wavy, electron-dense lamellae with a 4-4.5-nm periodicity. Type D MS were conglomerated masses of intricately arranged double or triple electron-dense layers (7.5-13.5 nm wide) alternating with wider (30-40-nm) electron-lucent layers. The electron-dense lamellae of type A, type C, and type D MS were stained with ruthenium red, the Thiéry method, and concanavalin A, indicating the presence of carbohydrate components. Freeze-fracture studies revealed smooth inner and outer surfaces in type A MS, with the fracture planes passing through the central parts of the trilaminar structures; the intervening layers contained 10-nm particles, which probably are proteins. Type B MS had smooth surfaces, and type C MS had slightly particulate surfaces; while type D MS showed tubular or polygonal structures, 350 nm wide, with rows of particles 7-8 nm in diameter. It is concluded that type A and type D MS contain proteins and carbohydrates, probably in the form of glycoproteins, as well as phospholipids, and are related to tubular myelin. Type B and type C MS are considered to contain mainly phospholipids; type C MS are also considered to contain carbohydrates and to be related to lamellar bodies of type II alveolar epithelial cells.

Luminal vesicles in endothelial cells of retinal and iridial vessels of the rat

Endothelial vesicles on the luminal front of retinal and iridial vessels were studied by perfusion fixation after intravenous injection of peroxidase, and by perfusion fixation of glutaraldehyde with tannic acid or ruthenium red. Many luminal vesicles contained peroxidase reaction product after intravenous injection of peroxidase, but were virtually empty after perfusion fixation. Both tannic acid and ruthenium red delineated the majority of luminal vesicles, singular or in clusters, surface-associated or "free" in the cytoplasm. Only a few free vesicles were unlabeled by the dye. No transendothelial channels were seen. The results suggest that most of the vesicles on the luminal front of endothelial cells are continuous with the cell surface at the time of fixation. The function of these vesicles is not fully understood; some appear to be involved in endocytosis of macromolecules from the vascular lumen.

Differential staining of biological structures by ruthenium red

After the application of a ruthenium red (RR) solution to smears of chicken and human blood for 15 min, thrombocyte and leucocyte nuclei showed a blue-grey colour, contrasting with the red-stained erythrocyte nuclei. Extracellular matrix in frozen sections of cartilage showed the blue-grey colour after 1 h of staining. After the application of RR for a prolonged time (24 h), goblet cell mucin, granules of salivary glands and starch granules in Epon-embedded tissues were coloured blue-grey, blue-green and brown-green respectively; although they appeared red after shorter staining times. Microspectrophotometric measurements of differentially stained structures, and correlation with the spectral behaviour of a related ruthenium compound (ruthenium violet), are presented. The formation in situ of this latter compound by interaction of RR with certain substrates and the capacity of RR to distinguish different cellular structures are discussed.

Calcium dependence of baclofen- and GABA-induced depression of responses to transmural stimulation in the guinea-pig isolated ileum

Both baclofen and gamma-aminobutyric acid (GABA) induced a dose-dependent depression of cholinergic twitch contractions in the transmurally stimulated guinea-pig isolated ileum. Over a range of 0.6-2.4 mM Ca2+, the degree of depression was inversely related to the Ca2+ concentration, with an increased sensitivity and sinistral shift of the dose-response curve at lower Ca2+ concentrations. Partial occupation of Ca2+ channels by Ruthenium Red (0.1 microM) also potentiated the depressive responses to baclofen and GABA. It is concluded that these agonists, acting through GABAB receptors, limit the availability of Ca2+ required for neurotransmitter release in myenteric motor nerves.

Viability and recovery from degranulation of isolated rat peritoneal mast cells

Using a culture system that allows prolonged maintenance of purified populations of peritoneal mast cells, we have examined them following stimulation by non-immunologic or immunologic agents. Employing phase-contrast microscopy of living cells and various pharmacological manipulations, we have noted that the recovery process includes a reduction in cell size, the probable sealing of exocytotic cavities, a pronounced displacement of the cell nucleus and a resynthesis of histamine. During recovery, mast cells can entrap molecules from the extracellular fluid and later release these substances by a Ca-dependent mechanism. Our results suggest that microfilaments, calmodulin, Ca, and metabolic energy are necessary for recovery.

An ultrastructural study of HeLa cell invasion with Salmonella typhi GIFU 10007

Scanning electron micrograph of HeLa S3 monolayered cells, inoculated with viable bacteria of a Salmonella typhi strain GIFU 10007, revealed that the extended microvilli tangled the bacteria within 10 min after inoculation. The micrographs of HeLa cells, at 1 hr after inoculation, indicate the following: shortening of bacterium-attached microvilli, subsiding of tangled bacteria into microvilli bush, and then attachment of bacterial soma to cell surface making the cell membrane depressed. The transmission electron micrographs, at 1 hr after inoculation, demonstrated the findings of interaction between HeLa cell and S. typhi 10007, similar to those observed on scanning electron micrographs. Hair-like fine structures from the soma of challenge organisms were also observed. They were in contact with HeLa cell microvilli and cell membrane. The bacteria were first partially and then totally surrounded by the HeLa cell plasma membrane. One, two, or several bacteria with intact outer membrane were enclosed in intracytoplasmic membrane-bound vacuoles. Fragmented vacuolar membrane was still visible around the intracellularly accumulated bacteria at 24 hr after inoculation. The viable cells of S. typhi 10007 are regarded as internalizing into HeLa cells by a process of endocytosis and to multiply within the membrane-bound vacuoles.

Ruthenium-red-stained polyanionic fixed charges in peritoneal microvessels

This study shows that the luminal surface of peritoneal microvascular endothelium, coated pits and coated vesicles are all negatively charged, unlike the limiting membrane of pinocytotic vesicles and transcellular channels. Our findings suggest that these cellular organelles have different functions as well as a different chemical composition. Anionic sites were observed along the subendothelial and subperithelial basal laminae of peritoneal capillaries and post capillary venules, respectively. Electric charge is a new parameter to be considered when analyzing transperitoneal transfer of charged macromolecules.

Correlation between virulence and colony morphology in Vibrio vulnificus

Of 38 isolates of Vibrio vulnificus examined, all avirulent strains produced only translucent colonies. All virulent strains, with the exception of biogroup 2 (eel pathogens), exhibited both opaque and translucent colonies. Isogenic morphotypes were examined for a variety of phenotypic and virulence traits. Only the ability to utilize transferrin-bound iron and the presence of a surface polysaccharide were found to correlate with colony opacity and virulence.