scholarly journals Regulation of the mitochondrial matrix volume in vivo and in vitro. The role of calcium

1986 ◽  
Vol 236 (3) ◽  
pp. 779-787 ◽  
Author(s):  
A P Halestrap ◽  
P T Quinlan ◽  
D E Whipps ◽  
A E Armston
Keyword(s):  
Liver Mitochondria ◽  
Ruthenium Red ◽  
Mitochondrial Swelling ◽  
Transport Systems ◽  
Matrix Volume ◽  
Specific Permeability ◽  
Mitochondrial Volume ◽  
Energy Dependent

The ability of alpha-adrenergic agonists and vasopressin to increase the mitochondrial volume in hepatocytes is dependent on the presence of extracellular Ca2+. Addition of Ca2+ to hormone-treated cells incubated in the absence of Ca2+ initiates mitochondrial swelling. In the presence of extracellular Ca2+, A23187 (7.5 microM) induces mitochondrial swelling and stimulates gluconeogenesis from L-lactate. Isolated liver mitochondria incubated in KCl medium in the presence of 2.5 mM-phosphate undergo energy-dependent swelling, which is associated with electrogenic K+ uptake and reaches an equilibrium when the volume has increased to about 1.3-1.5 microliter/mg of protein. This K+-dependent swelling is stimulated by the presence of 0.3-1.0 microM-Ca2+, leading to an increase in matrix volume at equilibrium that is dependent on [Ca2+]. Ca2+-activated K+-dependent swelling requires phosphate and shows a strong preference for K+ over Na+, Li+ or choline. It is not associated with either uncoupling of mitochondria or any non-specific permeability changes and cannot be produced by Ba2+, Mn2+ or Sr2+. Ca2+-activated K+-dependent swelling is not prevented by any known inhibitors of plasma-membrane ion-transport systems, nor by inhibitors of mitochondrial phospholipase A2. Swelling is inhibited by 65% and 35% by 1 mM-ATP and 100 microM-quinine respectively. The effect of Ca2+ is blocked by Ruthenium Red (5 micrograms/ml) at low [Ca2+]. Spermine (0.25 mM) enhanced the swelling seen on addition of Ca2+, correlating with its ability to increase Ca2+ uptake into the mitochondria as measured by using Arsenazo-III. Mitochondria derived from rats treated with glucagon showed less swelling than did control mitochondria. In the presence of Ruthenium Red and higher [Ca2+], the mitochondria from hormone-treated animals showed greater swelling than did control mitochondria. These data imply that an increase in intramitochondrial [Ca2+] can increase the electrogenic flux of K+ into mitochondria by an unknown mechanism and thereby cause swelling. It is proposed that this is the mechanism by which alpha-agonists and vasopressin cause an increase in mitochondrial volume in situ.

scholarly journals Partial inhibition by cyclosporin A of the swelling of liver mitochondria in vivo and in vitro induced by sub-micromolar [Ca2+], but not by butyrate. Evidence for two distinct swelling mechanisms

1990 ◽  
Vol 268 (1) ◽  
pp. 147-152 ◽  
Author(s):  
A M Davidson ◽  
A P Halestrap
Keyword(s):  
Light Scattering ◽  
Cyclosporin A ◽  
Binding Sites ◽  
Mitochondrial Protein ◽  
Liver Mitochondria ◽  
Partial Inhibition ◽  
Mitochondrial Volume ◽  
Bongkrekic Acid

1. The effects of cyclosporin A on the increase in matrix PPi and consequent swelling of energized liver mitochondria incubated with 1 mM-butyrate, 30 microM-bongkrekic acid or 0.1-35 microM-Ca2+ [Halestrap (1989) Biochim. Biophys. Acta 973, 355-382] were studied. 2. Cyclosporin (1 microM) had no significant effect on the swelling induced by butyrate, bongkrekic acid or Ca2+ at concentrations of less than 0.3 microM. 3. At higher [Ca2+] (greater than 0.3 microM), swelling became progressively inhibited by cyclosporin, although the increase in matrix PPi was slightly greater in the presence than in the absence of cyclosporin. 4. Titration with cyclosporin indicated that there are 128 pmol of relevant cyclosporin-binding sites per mg of mitochondrial protein, with a Ki of about 5 nM. 5. The decrease in light-scattering by hepatocytes induced by butyrate [Davidson & Halestrap (1988) Biochem. J. 254, 379-384] was unaffected by cyclosporin, whereas that induced by vasopressin was inhibited by 20-30% without a significant change in cellular PPi content. 6. It is suggested that there are two mechanisms for the increase in mitochondrial volume induced by Ca2+: a PPi-mediated mechanism that is insensitive to cyclosporin and an additional Ca2(+)-mediated effect that is inhibited by cyclosporin. The nature of these pathways and their inter-relationship is discussed in the following paper [Halestrap & Davidson (1990) Biochem. J. 268, 153-160].

scholarly journals Maturation in liver mitochondria of Ruthenium Red-sensitive calcium-ion-transport activity and the influence of glucagon administration in vivo and in utero

1981 ◽  
Vol 196 (1) ◽  
pp. 207-216
Author(s):  
Veronica Prpić ◽  
Fyfe L. Bygrave
Keyword(s):  
Rat Liver ◽  
Post Partum ◽  
Liver Mitochondria ◽  
In Utero ◽  
Ruthenium Red ◽  
Protonmotive Force ◽  
Period 2 ◽  
Calcium Ion Transport ◽  
Energy Dependent

The maturation of Ca2+ transport in mitochondria isolated from rat liver was examined, from 5 days before birth. The mitochondria used were isolated from liver homogenates by centrifugation at 22000g-min. Ca2+ transport by mitochondria isolated from foetal liver is energy-dependent and Ruthenium Red-sensitive. The transmembrane pH gradient in these mitochondria is higher by about 7mV and the membrane potential lower by about 20mV than in adult mitochondria. The inclusion of 2mm-Pi in the incubation medium enhances the protonmotive force by approx. 30mV. The rate of Ca2+ influx in foetal mitochondria measured in buffered KCl plus succinate is low until about 2–3h after birth, when it increases to about 60% of adult values; approx. 24h later it has reached near-adult values. Higher rates of Ca2+ influx are observed in the presence of 2mm-Pi; 3–5 days before birth the rates are about one-third of adult values and decline slightly as birth approaches. By 2–3h post partum they have reached adult values. The inclusion of 12.5μm-MgATP with the Pi stimulates further the initial rate of Ca2+ influx in foetal mitochondria. The rates observed are constant over the prenatal period examined and are 50–60% of those observed in adult mitochondria. Mitochondria isolated from foetal livers 4–5 days before birth retain the accumulated Ca2+ for about 50min in the presence of 2mm-Pi. In the period 2 days before birth to birth, this ability is largely lost, but by 2–3h after birth Ca2+ retention is similar to that of adult mitochondria. The presence of 12.5μm-MgATP progressively enhances the Ca2+ retention time as development proceeds until 2–3h after birth, when it becomes less sensitive to added MgATP. Glucagon administration to older foetuses in utero enhances both the rate of mitochondrial Ca2+ influx assayed in the presence of 2mm-Pi and the time for which mitochondria retain accumulated Ca2+ in the presence of 12.5μm-MgATP and 2mm-Pi. Its administration to neonatal animals leads to an increase in mitochondrial Ca2+ retention similar to that seen in adult mitochondria. The data provide evidence that the Ruthenium Red-sensitive Ca2+ transporter is potentially as active in foetal mitochondria 5 days before birth as it is in adult mitochondria. They also show that foetal mitochondria have an ability to retain accumulated Ca2+ reminiscent of mitochondria from tumour cells and from hormone-challenged rat liver.

scholarly journals Vascular Dysfunction Induced by Mercury Exposure

2019 ◽  
Vol 20 (10) ◽  
pp. 2435 ◽  
Author(s):  
Tetsuya Takahashi ◽  
Takayoshi Shimohata
Keyword(s):  
Oxidative Stress ◽  
Vascular Dysfunction ◽  
Brain Parenchyma ◽  
Transport Systems ◽  
Mehg Exposure ◽  
In Vivo Models ◽  
The Central Nervous System ◽  
The Brain

Methylmercury (MeHg) causes severe damage to the central nervous system, and there is increasing evidence of the association between MeHg exposure and vascular dysfunction, hemorrhage, and edema in the brain, but not in other organs of patients with acute MeHg intoxication. These observations suggest that MeHg possibly causes blood–brain barrier (BBB) damage. MeHg penetrates the BBB into the brain parenchyma via active transport systems, mainly the l-type amino acid transporter 1, on endothelial cell membranes. Recently, exposure to mercury has significantly increased. Numerous reports suggest that long-term low-level MeHg exposure can impair endothelial function and increase the risks of cardiovascular disease. The most widely reported mechanism of MeHg toxicity is oxidative stress and related pathways, such as neuroinflammation. BBB dysfunction has been suggested by both in vitro and in vivo models of MeHg intoxication. Therapy targeted at both maintaining the BBB and suppressing oxidative stress may represent a promising therapeutic strategy for MeHg intoxication. This paper reviews studies on the relationship between MeHg exposure and vascular dysfunction, with a special emphasis on the BBB.

scholarly journals Evaluation of 3-l- and 3-d-[18F]Fluorophenylalanines as PET Tracers for Tumor Imaging

Cancers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 6030
Author(s):  
Felicia Krämer ◽  
Benedikt Gröner ◽  
Chris Hoffmann ◽  
Austin Craig ◽  
Melanie Brugger ◽  
...  
Keyword(s):  
Amino Acid ◽  
Tumor Imaging ◽  
Human Tumor ◽  
Transport Systems ◽  
Acid Decarboxylase ◽  
Tumor Xenografts ◽  
Tumor Delineation ◽  
Mcf 7

Purpose: The preclinical evaluation of 3-l- and 3-d-[18F]FPhe in comparison to [18F]FET, an established tracer for tumor imaging. Methods: In vitro studies were conducted with MCF-7, PC-3, and U87 MG human tumor cell lines. In vivo µPET studies were conducted in healthy rats with/without the inhibition of peripheral aromatic l-amino acid decarboxylase by benserazide pretreatment (n = 3 each), in mice bearing subcutaneous MCF-7 or PC-3 tumor xenografts (n = 10), and in rats bearing orthotopic U87 MG tumor xenografts (n = 14). Tracer accumulation was quantified by SUVmax, SUVmean and tumor-to-brain ratios (TBrR). Results: The uptake of 3-l-[18F]FPhe in MCF-7 and PC-3 cells was significantly higher relative to [18F]FET. The uptake of all three tracers was significantly reduced by the suppression of amino acid transport systems L or ASC. 3-l-[18F]FPhe but not 3-d-[18F]FPhe exhibited protein incorporation. In benserazide-treated healthy rats, brain uptake after 42–120 min was significantly higher for 3-d-[18F]FPhe vs. 3-l-[18F]FPhe. [18F]FET showed significantly higher uptake into subcutaneous MCF-7 tumors (52–60 min p.i.), while early uptake into orthotopic U87 MG tumors was significantly higher for 3-l-[18F]FPhe (SUVmax: 3-l-[18F]FPhe, 107.6 ± 11.3; 3-d-[18F]FPhe, 86.0 ± 4.3; [18F]FET, 90.2 ± 7.7). Increased tumoral expression of LAT1 and ASCT2 was confirmed immunohistologically. Conclusion: Both novel tracers enable accurate tumor delineation with an imaging quality comparable to [18F]FET.

The ultrastructure of Candida albicans infections

1981 ◽  
Vol 27 (11) ◽  
pp. 1156-1164 ◽  
Author(s):  
Thomas J. Marrie ◽  
J. William Costerton
Keyword(s):  
Candida Albicans ◽  
Oral Candidiasis ◽  
Ruthenium Red ◽  
Host Cells ◽  
Yeast Cells ◽  
Positive Matrix ◽  
Urine Sediment ◽  
Bacteria Adhesion

Scrapings of Candida albicans plaques from the tongue and buccal mucosa of patients with oral candidiasis were examined electron microscopy. In addition, urine sediment from patients with infection of their catheterized urinary tracts was similar examined. Three types of C. albicans – oral epithelial cell interactions were noted: a loose adherence apparently mediated by ruthenium red positive matrix, a "tight" adherence where no space could be seen between the host and yeast cell, and invasions host cells by yeast hyphal elements. Adhesion of Candida blastospores to hyphal elements and adhesion of bacteria to Candida cells was also frequently observed.Urine sediments from patients with mixed bacteria–yeast infections demonstrated adhesion of the bacteria to the yeast cells. This phenomenon was also demonstrated in in vitro experiments and fibrous ruthenium red material invariably occupied the zo*** of adhesion.Phagocytosis of yeast by polymorphonuclear leukocytes was found in urinary, but not in oral, candidiasis. Our in vivo and vitro observations indicate that a ruthenium red positive matrix covers the surfaces involved in the yeast to yeast, yeast to ho and yeast to bacteria adhesion.

Recent findings on oogenesis of Drosophila melanogaster

Development ◽  
1977 ◽  
Vol 38 (1) ◽  
pp. 125-138
Author(s):  
F. Giorgi ◽  
J. Jacob
Keyword(s):  
Drosophila Melanogaster ◽  
Fat Body ◽  
Radioactive Tracer ◽  
Superficial Layer ◽  
Ruthenium Red ◽  
Time Interval ◽  
Intracellular Location ◽  
Short Time

Vitellogenic ovaries from Drosophila melanogaster flies have been exposed, either in in vivo or in vitro conditions, to various extracellular tracers in an attempt to determine the possible route of entry of the yolk precursors. Ruthenium red and lanthanum nitrate have been shown to gain access to the oocyte surface by initially passing through the intercellular spaces of the follicle layer. Both these tracers, however, never attain an intracellular location within any of the cells forming the ovarian chamber. Colloidal Thorotrast when injected into adult females has never been detected within any of the ovarian chambers examined, irrespective of their stage. Vitellogenic oocytes exposed to peroxidase in in vivo conditions exhibit the oolemma and all the structural elements present in the cortical ooplasm well labelled within a very short time after the injection. Moreover, with gradually increasing exposure times to peroxidase, the labelled yolk platelets increase progressively in number. At each time interval after the injection, the label over the yolk platelets remains restricted to the superficial layer and never gets into the associated body. The pattern of tritiated lysine incorporation into vitellogenic oocytes has been studied over a period of 20 h. A few hours after injection of the radioactive tracer, the silver grains located over the ooplasm appear distributed at random. A predominant labelling of the yolk platelets as compared to the rest of the ooplasm, becomes evident only with a 6 h delay since the time of injection. When analysed by electrophoresis and isolectrofocusing, the vitellogenic ovary is seen to exhibit a number of protein bands which are common to those of other tissues as, for instance, haemolymph and fat body. The evidence obtained in the present study is discussed in relation to the hypothesis of an extraovarian origin of the yolk precursors and their sequestration into forming yolk platelets.

scholarly journals Effects of 2-mercaptoacetate in isolated liver mitochondria in vitro. Competitive inhibition of 3-hydroxybutyrate dehydrogenase and depression of the β-oxidation pathway

1982 ◽  
Vol 206 (1) ◽  
pp. 53-59 ◽  
Author(s):  
F Bauché ◽  
D Sabourault ◽  
Y Giudicelli ◽  
J Nordmann ◽  
R Nordmann
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Oxidation ◽  
Competitive Inhibition ◽  
Liver Mitochondria ◽  
Inhibitory Effect ◽  
Acid Oxidation ◽  
Membrane Bound ◽  
Energy Dependent ◽  
Isolated Liver

The effects of 2-mercaptoacetate on the respiration rates induced by different substrates were studied in vitro in isolated liver mitochondria. With palmitoyl-L-carnitine or 2-oxoglutarate as the substrate, the ADP-stimulated respiration (State 3) was dose-dependently inhibited by 2-mercaptoacetate. with glutamate or succinate as the substrate. State-3 respiration was only slightly inhibited by 2-mercaptoacetate. In contrast, the oxidation rate of 3-hydroxybutyrate was competitively inhibited by 2-mercaptoacetate in both isolated mitochondria and submitochondrial particles. In uncoupled mitochondria and in mitochondria in which ATP- and GTP-dependent acyl-CoA biosynthesis was inhibited, the inhibitory effect of 2-mercaptoacetate on palmitoyl-L-carnitine oxidation was abolished; under the same conditions, however, inhibition of 3-hydroxybutyrate oxidation by 2-mercaptoacetate still persisted. These results led to the following conclusions: 2-mercaptoacetate itself enters the mitochondrial matrix, inhibits fatty acid oxidation through a mechanism requiring an energy-dependent activation of 2-mercaptoacetate and itself inhibits 3-hydroxybutyrate oxidation through a competitive inhibition of the membrane-bound 3-hydroxybutyrate dehydrogenase. This study also strongly suggests that the compound responsible for the inhibition of fatty acid oxidation is 2-mercaptoacetyl-CoA.

Paradoxical effect of methimazole on liver mitochondria: In vitro and in vivo

2016 ◽  
Vol 259 ◽  
pp. 108-115 ◽  
Author(s):  
Hossein Niknahad ◽  
Akram Jamshidzadeh ◽  
Reza Heidari ◽  
Zeynab Hosseini ◽  
Keivan Mobini ◽  
...  
Keyword(s):  
Liver Mitochondria ◽  
Paradoxical Effect

Phosphatidylethanolamine in Liver Mitochondria and Endoplasmic Reticulum; Molecular Species Distribution and Turnover

1975 ◽  
Vol 53 (6) ◽  
pp. 698-705 ◽  
Author(s):  
J. G. Parkes ◽  
W. Thompson
Keyword(s):  
Endoplasmic Reticulum ◽  
Fatty Acid ◽  
Specific Activity ◽  
Liver Mitochondria ◽  
Relative Activity ◽  
Layer Chromatography ◽  
Kinetics Of ◽  
Fatty Acid Compositions

Phosphatidylethanolamine from mitochondria and microsomes of guinea pig liver was separated by thin-layer chromatography into eight different classes differing in degree of unsaturation. The fatty acid compositions and molar proportions of each class isolated from microsomes were very similar to the corresponding class in mitochondria. In both organelles about half of the total was dienoic species while tetraenes comprised approximately 20%. Stearic acid was the major saturated fatty acid and in each membrane a greater selectivity for stearate over palmitate was found in each sub-class of phosphatidylethanolamine, when compared with the corresponding class of phosphatidylcholine.Following the intraperitoneal injection of [2-3H]glycerol, the labelling of each molecular class of phosphatidylethanolamine showed very similar progressions in microsomes and mitochondria over a 3 h interval. In both organelles the highest relative specific activity was attained by penta-plus hexaenoic classes, while the large dienoic class had the lowest relative activity, which, however, increased with time. Analysis of the dienoic class of phosphatidylethanolamine from whole liver showed it to be constituted by a rapidly turning over palmitoyl–linoleoyl fraction and a slowly labelled stearoyl–linoleoyl fraction, a pattern also exhibited by dienoic phosphatidylcholines.The similarities in profile of molecular classes of phosphatidylethanolamine and in the kinetics of labelling in vivo point to a close metabolic relation between the lipids of both organelles, suggestive of a transfer of different molecular classes at comparable rates from the endoplasmic reticulum, the site of synthesis, to the mitochondria. This is consistent with numerous other studies in vitro that have demonstrated inter-organelle exchange of lipids.

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