Involvement of a cytoplasmic protein in calcium-dependent potassium efflux in red blood cells

1986 ◽  
Vol 251 (4) ◽  
pp. C535-C540 ◽  
Author(s):  
G. A. Plishker ◽  
P. H. White ◽  
E. D. Cadman
Keyword(s):  
Calcium Concentration ◽  
Protein Band ◽  
Iodoacetic Acid ◽  
Inhibitory Effect ◽  
Cytoplasmic Protein ◽  
Potassium Efflux ◽  
Potassium Permeability ◽  
Calcium Dependent ◽  
Free Intracellular Calcium ◽  
Lines Of Evidence

The potassium permeability of the human red blood cell increases with the free intracellular calcium concentration. The efflux of potassium can be inhibited by iodoacetic acid. This inhibitory effect correlates directly with the carboxymethylation of a protein band found in both the hemolysate and membrane fractions. The present study provides two additional lines of evidence that this protein is involved directly with the calcium-dependent changes in potassium permeability: its association with the membrane is calcium dependent; and calcium-dependent potassium efflux from resealed ghost is inhibited by the incorporation of antibodies raised against this cytoplasmic protein.

Iodoacetic acid inhibition of calcium-dependent potassium efflux in red blood cells

1985 ◽  
Vol 248 (5) ◽  
pp. C419-C424 ◽  
Author(s):  
G. A. Plishker
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Protein Band ◽  
Iodoacetic Acid ◽  
Specific Protein ◽  
Metabolic Inhibitor ◽  
Potassium Efflux ◽  
Calcium Dependent ◽  
Irreversible Inhibition ◽  
Cellular Ca

The metabolic inhibitor, iodoacetic acid (IAA), has commonly been used to increase Ca-dependent K efflux in red blood cells. It is thought that this effect of IAA involves the irreversible inhibition of glyceraldehyde-phosphate dehydrogenase (EC 1.2.1.12), resulting in the energy depletion of the cell. Without energy, active transport stops, and the K loss is enhanced both by increasing cellular Ca and by preventing K reuptake. The present study shows that in addition to this metabolic effect, which increases Ca-dependent K efflux, IAA also inhibits this efflux. This inhibition is irreversible and is not related to the ATP or Ca concentrations of the cells. The carboxymethylation of a specific protein band correlates with IAA inhibition of K efflux.

scholarly journals Anti-Allergy Potential of Averrhoa bilimbi Linn. Fruit Water Extract Shown by Its Suppressive Effect on the Degranulation of RBL-2H3 Cells

2021 ◽  
pp. 81-88
Author(s):  
William Halim Santoso ◽  
Momoko Ishida ◽  
Kosuke Nishi ◽  
Takuya Sugahara ◽  
Agus Budiawan Naro Putra
Keyword(s):  
Calcium Concentration ◽  
Water Extract ◽  
Allergic Diseases ◽  
Suppressive Effect ◽  
Inhibitory Effect ◽  
Current Evidence ◽  
Polyphenol Content ◽  
Calcium Dependent ◽  
Active Substances

Allergy rhinitis (AR), as reported by the World Allergy Organization (WAO), is one of the highest prevalence allergies affecting 10-30% of all adults and up to 40% of children. In Indonesia, current evidence showed that the prevalence of AR is increasing. Averrhoa bilimbi Linn. fruit (AF), or locally known as belimbing wuluh, has been scientifically proven to treat many diseases due to the abundant of polyphenol content which was shown to have the potential to treat allergies. Therefore, this study was aimed to investigate the anti-allergy potential of AF in vitro. The anti-allergy effect of Averrhoa bilimbi Linn. fruit water extract (AFWE) was examined using RBL-2H3 cells. At first, the cytotoxicity effect of AFWE was determined by WST-8 assay. The release of β-hexosaminidase by RBL-2H3 cells was also measured to evaluate degranulation suppression activity of AFWE. Lastly, calcium assay was employed to investigate the intracellular calcium concentration ([Ca­2+]i). Results demonstrated that AFWE does not show any cytotoxicity at any given concentration. In addition, AFWE at 1.25 mg/mL showed sufficient inhibitory effect towards degranulation by RBL-2H3 cells. Moreover, the degranulation-suppressing activity of AFWE was resulted from the inhibition of calcium-dependent signaling pathways. Unfortunately, the properties of active substances from AFWE have not been investigated. To conclude, this study indicated that AFWE has potential as an alternative treatment for allergic diseases.

The origin of passive force enhancement in skeletal muscle

2008 ◽  
Vol 294 (1) ◽  
pp. C74-C78 ◽  
Author(s):  
V. Joumaa ◽  
D. E. Rassier ◽  
T. R. Leonard ◽  
W. Herzog
Keyword(s):  
Calcium Concentration ◽  
Force Production ◽  
Primary Source ◽  
Passive Force ◽  
Active Force ◽  
Force Enhancement ◽  
Bridge Formation ◽  
Calcium Dependent ◽  
Cross Bridge ◽  
High Calcium

The aim of the present study was to test whether titin is a calcium-dependent spring and whether it is the source of the passive force enhancement observed in muscle and single fiber preparations. We measured passive force enhancement in troponin C (TnC)-depleted myofibrils in which active force production was completely eliminated. The TnC-depleted construct allowed for the investigation of the effect of calcium concentration on passive force, without the confounding effects of actin-myosin cross-bridge formation and active force production. Passive forces in TnC-depleted myofibrils ( n = 6) were 35.0 ± 2.9 nN/ μm2 when stretched to an average sarcomere length of 3.4 μm in a solution with low calcium concentration (pCa 8.0). Passive forces in the same myofibrils increased by 25% to 30% when stretches were performed in a solution with high calcium concentration (pCa 3.5). Since it is well accepted that titin is the primary source for passive force in rabbit psoas myofibrils and since the increase in passive force in TnC-depleted myofibrils was abolished after trypsin treatment, our results suggest that increasing calcium concentration is associated with increased titin stiffness. However, this calcium-induced titin stiffness accounted for only ∼25% of the passive force enhancement observed in intact myofibrils. Therefore, ∼75% of the normally occurring passive force enhancement remains unexplained. The findings of the present study suggest that passive force enhancement is partly caused by a calcium-induced increase in titin stiffness but also requires cross-bridge formation and/or active force production for full manifestation.

Magnesium requirement for somatostatin inhibition of insulin secretion

1984 ◽  
Vol 105 (1) ◽  
pp. 83-86 ◽  
Author(s):  
Donald L. Curry ◽  
Leslie L. Bennett
Keyword(s):  
Insulin Secretion ◽  
Calcium Concentration ◽  
Inhibitory Effect ◽  
Secretory Process ◽  
Magnesium Ion ◽  
Second Phase ◽  
Intracellular Membrane ◽  
Calcium Magnesium ◽  
First Phase Insulin Secretion ◽  
Insulin Secretory Response

Abstract. Rat pancreas perfusions were performed using a perfusate with a fixed calcium concentration of 5 mEq/l and magnesium varying from 0 to 0.6 mEq/dl. Insulin secretion was stimulated by a constant glucose infusion of 300 mg/dl. This glucose concentration produces the typical biphasic insulin secretory response. We observed that in the absence of magnesium, somatostatin concentrations of 0.5 and 2.0 ng/ml were without effect on first phase insulin secretion. However, these same somatostatin levels produced 50% or more inhibition of insulin secretion in the presence of magnesium at 0.3 or 0.6 mEq/l. Similarly, in the absence of magnesium, somatostatin at 50 ng/ml failed to inhibit second phase insulin secretion, whereas this same somatostatin level produced about 50% inhibition of insulin secretion in the presence of magnesium at 0.3 mEq/l. Thus, altering perfusate magnesium concentrations without changing calcium is an important determinant of the degree of inhibition of secretion produced by somatostatin. In particular, in the absence of magnesium ion, somatostatin concentrations which would 'normally' produce 50% inhibition of secretion (ID50) are without effect. Therefore, magnesium ion is necessary for the full inhibitory effect of somatostatin to occur. These results suggest that inhibitors, as well as potentiators, of the insulin secretory process may act by altering intracellular/membrane calcium-magnesium ratios, but in opposite directions.

Inactivation of Calcium-Dependent Lactic Acid Bacteria Phages by Phosphates

2007 ◽  
Vol 70 (6) ◽  
pp. 1518-1522 ◽  
Author(s):  
V. B. SUÁREZ ◽  
M. L. CAPRA ◽  
M. RIVERA ◽  
J. A. REINHEIMER
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Sodium Tripolyphosphate ◽  
Culture Media ◽  
Divalent Cations ◽  
Skim Milk ◽  
Inhibitory Effect ◽  
Lytic Cycle ◽  
High Solubility ◽  
Calcium Dependent

The capacity of three phosphates to interrupt the lytic cycle of four specific autochthonal bacteriophages of lactic acid bacteria used as starters was assayed. The phosphates used (polyphosphates A and B and sodium tripolyphosphate–high solubility [TAS]) were selected on the basis of their capacity to sequester divalent cations, which are involved in the lytic cycle of certain bacteriophages. The assays were performed in culture media (deMan Rogosa Sharpe and Elliker broths) and reconstituted (10%, wt/vol) commercial skim milk to which phosphates had been added at concentrations of 0.1, 0.3, and 0.5% (wt/vol). Phosphate TAS was the most inhibitory one, since it was able to inhibit the lytic cycle of all bacteriophages studied, in both broths and milk. In broth, polyphosphates A and B inhibited the lytic cycle of only two bacteriophages at the maximal concentration used (0.5%), whereas in milk, they were not capable of maintaining the same inhibitory effect.

scholarly journals Specificity and Prevalence of Natural Bovine Antimannan Antibodies

1999 ◽  
Vol 6 (6) ◽  
pp. 946-952 ◽  
Author(s):  
Abhay Srinivasan ◽  
Yawei Ni ◽  
Ian Tizard
Keyword(s):  
Age Groups ◽  
Inhibitory Effect ◽  
Enzyme Linked Immunosorbent Assay ◽  
Dependent Manner ◽  
Serum Samples ◽  
Adult Cattle ◽  
Calcium Dependent ◽  
High Concentrations ◽  
Carbohydrate Components ◽  
A Minor

ABSTRACT Immune responses to the carbohydrate components of microorganisms, mediated both by antibodies and by lectins, are an important part of host defense. In the present experiments, the specificity and presence of natural bovine antibodies against mannan, a common fungal antigen, were examined by enzyme-linked immunosorbent assay (ELISA), usingSaccharomyces cerevisiae mannan as an antigen. The results showed that all serum samples from animals of three age groups (newborn, calf, and adult) tested contained antimannan antibodies, and the titer of these antibodies increased significantly in adults. However, titers among individual adult cattle differed widely. Inhibition assays showed that yeast mannan was the strongest inhibitor.d-Mannose exhibited only a minor inhibitory effect at high concentrations. This suggests that most of these antibodies recognize an oligosaccharide-based epitope(s) different from those recognized by lectins. Cattle possess three serum C-type lectins (collectins) capable of recognizing mannan in a calcium-dependent manner. Addition of EDTA to the reaction did not reduce antibody binding, suggesting that the binding of these antibodies to mannan was not affected by the presence of collectin. The antibodies purified from either calf or adult serum by mannan-Sepharose affinity chromatography consisted of mainly immunoglobulin G (IgG) and a smaller amount of IgM. IgG1 was shown to be the dominant antimannan IgG isotype by isotype-specific ELISA. Together, these results demonstrate the production of natural antimannan antibodies in cattle in an age-dependent manner. These antibodies might be involved in defending the host against mannan-containing pathogens as a specific line of defense in conjunction with the innate response by lectins.

Diffusion, Buffering, and Binding

1998 ◽  
Author(s):  
Christof Koch
Keyword(s):  
Synaptic Plasticity ◽  
Intracellular Calcium ◽  
Temporal Dynamics ◽  
Critical Concentration ◽  
Two Photon Microscopy ◽  
Calcium Dependent ◽  
Calcium Sensors ◽  
Free Intracellular Calcium ◽  
Messenger Molecules ◽  
Spatio Temporal

In Chap. 9 we introduced calcium ions and alluded to their crucial role in regulating the day-to-day life of neurons. The dynamics of the free intracellular calcium is controlled by a number of physical and chemical processes, foremost among them diffusion and binding to a host of different proteins, which serve as calcium buffers and as calcium sensors or triggers. Whereas buffers simply bind Ca2+ above some critical concentration, releasing it back into the cytoplasm when [Ca2+]i has been reduced below this level, certain proteins— such as calmodulin—change their conformation when they bind with Ca2+ ions, thereby activating or modulating enzymes, ionic channels, or other proteins. The calcium concentration inside the cell not only determines the degree of activation of calcium-dependent potassium currents but—much more importantly—is relevant for determining the changes in structure expressed in synaptic plasticity. As discussed in Chap. 13, it is these changes that are thought to underlie learning. Given the relevance of second messenger molecules, such as Ca2+, IP3, cyclic AMP and others, for the processes underlying growth, sensory adaptation, and the establishment and maintenance of synaptic plasticity, it is crucial that we have some understanding of the role that diffusion and chemical kinetics play in governing the behavior of these substances. Today, we have unprecedented access to the spatio-temporal dynamics of intracellular calcium in individual neurons using fluorescent calcium dyes, such as fura-2 or fluo-3, in combination with confocal or two-photon microscopy in the visible or in the infrared spectrum (Tsien, 1988; Tank et al., 1988; Hernández-Cruz, Sala, and Adams, 1990; Ghosh and Greenberg, 1995).

Axotomy induces a transient and localized elevation of the free intracellular calcium concentration to the millimolar range

1995 ◽  
Vol 74 (6) ◽  
pp. 2625-2637 ◽  
Author(s):  
N. E. Ziv ◽  
M. E. Spira
Keyword(s):  
Intracellular Calcium ◽  
Calcium Concentration ◽  
Intracellular Calcium Concentration ◽  
Concentration Gradients ◽  
Fura 2 ◽  
Direct Demonstration ◽  
Free Intracellular Calcium ◽  
Axonal Transection ◽  
Transient Elevation

1. Axonal transection triggers a cascade of pathological processes that frequently lead to the degeneration of the injured neuron. It is generally believed that the degenerative process is triggered by an overwhelming influx of calcium through the cut end of the axon. 2. Theoretical considerations and indirect observations suggest that axotomy is followed by an increase in the free intracellular calcium concentration ([Ca2+]i) to the millimolar level. In contrast, only relatively modest and transient elevation in [Ca2+]i to the micromolar level was revealed by recent fura-2 studies. 3. In the current study we used the low-affinity Ca2+ indicator mag-fura-2 to reexamine the spatiotemporal distribution pattern of Ca2+ after axotomy and to map the free intracellular Mg2+ concentration gradients. 4. We report that axotomy elevates [Ca2+]i well beyond the "physiological" range of calcium concentrations, to levels > 1 mM near the tip of the cut axon and to hundreds of micromolars along the axon further away from the cut end. Nevertheless, [Ca2+]i recovers to the control levels within 2-3 min after the resealing of the cut end. 5. A comparison of the behavior of fura-2 and mag-fura-2 in the cytosol of the axotomized neurons reveals that the determination of [Ca2+]i by fura-2 largely underestimates the actual intracellular Ca2+ concentrations. 6. Experiments in which one branch of a bifurcated axon was transected revealed that the elevation in [Ca2+]i is confined to the transected axonal branch and does not spread beyond the bifurcation point. 7. After axotomy, the intracellular Mg2+ concentration equilibrates rapidly with the external concentration and then recovers at a rate somewhat slower than that of [Ca2+]i. 8. To the best of our knowledge, this study is the first direct demonstration that axotomy elevates [Ca2+]i to the millimolar range and that neurons are able to recover from these extreme calcium concentrations.

scholarly journals Increased membrane binding of erythrocyte catalase in hereditary spherocytosis and in metabolically stressed normal cells

Blood ◽  
1977 ◽  
Vol 49 (1) ◽  
pp. 113-123 ◽  
Author(s):  
DW Allen ◽  
S Cadman ◽  
SR McCann ◽  
B Finkel
Keyword(s):  
Molecular Weight ◽  
Hereditary Spherocytosis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Membrane Binding ◽  
Sodium Dodecyl ◽  
Protein Band ◽  
Normal Cells ◽  
Calcium Dependent ◽  
Subunit Molecular Weight ◽  
Erythrocyte Catalase

Abstract Normal red blood cell (RBC) membranes were compared with (1) RBC membranes from six patients with hereditary spherocytosis (HS), (2) normal membranes after hemolysis of the RBC in the presence of calcium, or (3) normal membranes after incubation of RBC for 24 hr in phosphate- buffered saline containing calcium without added glucose. When compared with normal controls, polyacrylamide gel electrophoresis with sodium dodecyl sulfate (PAGE SDS) of all three preparations showed an increase in membrane binding of globin and protein band 4.5 (60,000 molecular weight). In an attempt to identify band 4.5, 14 enzymes were assayed in the RBC membranes. Of these, catalase and lactate dehydrogenase were increased in membranes from HS RBC and from normal cells exposed to calcium. Only catalase, however, was present in sufficient quantity and had the correct subunit molecular weight on PAGE SDS and calcium- dependent membrane binding to account for an appreciable portion of 4.5. Caralase was further identified with a component of band 4.5 by double immunodiffusion using a specific anti-catalase antibody.

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