Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Neutral Red”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 379 records · Page 21Linked to original sources
PubMed2004

Investigation on DNA assembly to neutral red-cyclodextrin complex by molecular spectroscopy.

DNA assembling to neutral red (NR) and cyclodextrins (CDs)-NR inclusion complex has been investigated by means of absorption, fluorescence and resonance light scattering (RLS). Depending on the molar ratio R of NR:DNA, the binding of NR with DNA involved in two processes at pH 7.50 and ionic strength 0.0045. The first process occurs in R>2.5, where the neutral form of NR was predominant and enhanced RLS was observed, indicating the aggregation of NR neutral form molecules on the molecular surface of DNA. The second process occurs in R<2.5, where an absorption band at 540 nm and a fluorescent excitation and emission band at 550 and 607 nm respectively provided compelling evidence that the binding of NR to DNA leaded to extensive NR protonation even at pH 7.50, and that a protonated NR (the acidic form of NR) can form DNA adducts with a binding mode different from that of the unprotonated form (the neutral form of NR). The results were also illustrated by the CDs-NR supramolecular system. The experimental data showed that CDs including beta-CD, hydroxypropyl-beta-CD (HP-beta-CD) and sulfobutylether-beta-CD (SBE-beta-CD) superior to include the neutral form of NR, in addition, the inclusion complex decomposed when it bound to DNA. Thus, the decomposed NR was also protonated to form DNA adducts with intercalative mode. In fact, CDs played a role to carry guest molecule to intercalate DNA. A related mechanism is proposed.

Absorption↗
PubMed1989

Neutral red-labeled influenza virus loses photosensitivity during absorption to host cells but not to erythrocytes.

Neutral red (NR)-labeled influenza virus is extremely photosensitive. Unlike NR-labeled picornaviruses which lose their photosensitivity only after penetrating the host cell, NR-labeled influenza virus loses most of its photosensitivity during adsorption at 4 degrees C. We demonstrate that the underlying reaction occurs within seconds of adsorption and that it is irreversible, i.e., NR virus eluted from chick embryo cells after adsorption is hardly photosensitive anymore. In contrast to this, NR virus adsorbed to and eluted from erythrocytes retains its original photosensitivity. We suggest that the loss of photosensitivity during adsorption of NR virus to host cells reflects a conformational change in the virion which is not elicited by adsorption to red blood cells.

Adsorption↗
PubMed2006

Microwave enhanced-sorption of dyestuffs to dual-cation organobentonites from water.

The microwave enhanced-sorption of dyestuffs such as Neutral Red S-BR, Neutral Dark Yellow GL and Acid Blue B onto organobentonites from water was investigated. The decolorization rates of various dyestuffs by organobentonites were increased from 18.0% to 71.8%, the saturated sorption capacity of Neutral Red S-BR and Acid Blue B were increased 83.9% and 76.3% by microwave irradiation, respectively. The value of the microwave enhanced-sorption parameter R(m) increased in the following order: Neutral Red S-BR>Acid Blue B>Neutral Dark Yellow GL, which corresponded with their aqueous solubility. The zeta potentials of particles were decreased greatly by microwave, which is very significant for improving both sorption of dyestuffs to organobentonites from water and the separation of the adsorbents from treated water.

Adsorption↗
PubMed1991

Time course of neutral red-induced autophagy in murine pancreatic acinar cells. A morphometrical and cytochemical study.

The knowledge of the time course of the influences of chemicals on autophagy is of great importance in the study of their modes of action and hence provides information relating the mechanism and dynamics of this catabolic process. Neutral red (NR) treatment has long been used to produce an accumulation of autolysosomes in different cell types. In the present study early (AV1), advanced (AV2) and late (AV3), as well as complex (fused) AVs (AVc) were distinguished. In our morphometrical measurements, we found all these AV subcompartments significantly expanded as early as 30 min after the injection of NR (0.4 mg/g b.wt.), i.e. a large number of AVs accumulated in the cells. Since cytoplasmic volume fraction (CVF) of AV increased 3-fold during this early period we conclude that, unlike vinblastine, NR is not a fusion inhibitor. Accumulation of AV1 (3-fold) in the presence of fusions possibly indicates that NR stimulates formation of AVs in this early period, after the accumulation of AVs continued. The maximal CVF of AVs were measured at 4 h, when 7.6% of the cytoplasmic volume was sequestered into the AV compartment, two third of which came from AV3. This finding indicates that NR is probably an inhibitor of intravacuolar degradation. However, the high rate of accumulation of AV2, AV3, and total AVs including a slower but still pronounced accumulation of AV1 cannot be explained solely from inhibition of degradation, but indicates a stimulated segregation (AV formation). Our results therefore argue for a possible coupling of the regulation of autophagic segregation and degradation since vinblastine and possibly some other degradation inhibitors were also found to stimulate AV formation in other studies. Another goal of this study was to follow the time course of changes in distribution of certain lysosomal enzymes after NR treatment. According to our enzyme cytochemical studies, acid phosphatase (AP) of untreated cells is mainly located in large and small lysosomal elements of the Golgi zone, aryl sulfatase B (AS) in trans-Golgi elements including pre-secretory granules and trimetaphosphatase (TP) in basal lysosomes. After NR injection TP seemed to appear first in AV1 whereas AP activity was characteristic of more advanced AVs. AS activity only occasionally appeared in AV3 and exclusively at late times after NR injection.

Acid Anhydride Hydrolases↗
PubMedDate not supplied

In vitro effects of cadmium on two different animal cell models.

The aim of this study was to assess comparatively the effects of cadmium on two different in vitro cell models, a cell line derived from proximal tubule renal cells (LLC-PK1) and haemocytes or blood cells of mussels (Mytilus galloprovincialis). Cells were seeded in 96-well microplates and exposed in vitro to different concentrations of cadmium (CdCl(2)) ranging from 10 to 2000 microM for haemocytes and from 1 to 100 microM for LLC-PK1 cells, added to the culture medium. After 24 h of exposure, different assays were performed on haemocytes: neutral red uptake, phagocytosis of neutral red-stained zymosan, XTT assay, activity of lysosomal acid phosphatase and demonstration of the actin cytoskeleton using TRITC-labeled phalloidin. Cell viability expressed as LC50 was 750 microM when using the neutral red assay and 400 microM with the XTT assay. The phagocytic ability and the activity of acid phosphatase increased significantly in cells treated with Cd in a non dose-dependent manner. Doses of Cd above 100 microM caused disruption of the actin cytoskeleton. In LLC-PK1 cells, cell viability expressed as LC50 was found to be around 40 microM when using the neutral red assay and 50-60 microM with MTT and LDH assays, respectively. These results show that mussel haemocytes are in general more resistant to Cd exposure than LLC-PK1 cells. Furthermore, Cd appears to stimulate phagocytic and lysosomal activities in haemocytes in vitro.

Acid Phosphatase↗
PubMed2000

The use of biological stains in the analysis of late Palaeozoic pteridosperm cuticles.

The use of biological stains in the cuticular analysis of late Palaeozoic pteridosperms based on specimens from the Stephanian Blanzy-Montceau Basin (Central France) is discussed. Bismarck Brown, Malachite Green G, Methylene Blue, Methyl Green, Neutral Red, Safranin T, and a double staining with Neutral Red and Malachite Green G, were tested. Bismarck Brown, Malachite Green G, Methylene Blue, and Neutral Red increase contrast and emphasize differences in cutinization. The double staining in Neutral Red and Malachite Green G enhances the three-dimensional morphology of complex epidermal structures. Safranin T increases contrast, emphasizes cutinization differences, and enhances the three-dimensional morphology of complex epidermal features. The colour photography of cuticles is normally not affected by the presence of stains, but some stains mask black-and-white half-tones.

Journal Article↗
PubMed1991

The cytotoxic effects of commonly used topical antimicrobial agents on human fibroblasts and keratinocytes.

This study evaluated the cytotoxicity of commonly used topical agents to human dermal fibroblasts and epidermal keratinocytes, which play a prominent role in wound healing. The effects of these topical agents were assessed using two separate assays for the fibroblasts--tritiated thymidine incorporation and the uptake of a vital dye (neutral red). Keratinocytes were evaluated with the neutral red assay. Serial dilutions of each of 10 commonly used topical agents produced decreases in both the uptake of neutral red and the incorporation of thymidine at clinically relevant doses. Only Neosporin G.U. irrigant showed no significant difference compared with controls in the assays for both the fibroblasts and the keratinocytes. Careful attention must be paid to which agent is used in the clinical setting, since many of these can have profound effects on cells that influence wound healing.

Acetates↗
PubMed1979

The buffering capacity of the internal phase of thylakoids and the magnitude of the pH changes inside under flashing light.

The buffering capacity inside thylakoids is determined and the magnitude of flash-induced pH changes inside is calibrated in the pH range from 6.4 to 8.1. The work is based on flash-induced absorption changes of neutral red in a chloroplast suspension in which the outer phase is strongly buffered by bovine serum albumin. It is shown that neutral red is bound inside thylakoids. The binding can be described by a simple isotherm with an apparent Km = 4 microM and satruation at 1 neutral red per 17 chlorophylls. The apparent pK of neutral red is shifted from 6.6 in solution to 7.25 when bound inside. It is demonstrated that neutral red is a clean indicator of pH changes inside, i.e. when properly used it shows no response to other events. Although bound it reports pH changes which occur in the internal osmolar (aqueous) volume of thylakoids. This is obvious from the influence of chemically very different buffers on the magnitude of the absorption changes of neutral red. These act in a manner proportional to their calculated buffering capacity in aqueous solution. The intrinsic buffering capacity of the internal phase is determined with the aid of these buffers, at pH 7.2 it is between 0.8 and 1 mM (at 60 mosM). The absence of large variations in the buffering capacity in the range from pH 6.4 to 8.1 suggests that proteinaceous groups are involved in addition to the lipids which may dominate the buffering capacity at lower pH. The magnitude of the internal pH change is arrpox. 0.6 (at pH 7.3) under stimulation of both photosystems with a short xenon flash of light.

Chloroplasts↗
PubMed1975

Agar plate method for detection and enumeration of alkylbenzenesulfonate-degrading microorganisms.

A simple method for detection and enumeration of alkylbenzenesulfonate (ABS)-degrading microorganisms by using agar plates was developed and used in microbiological studies of coastal marine and polluted river waters. The method depends upon the color responses of neutral red in alkaline medium. Neutral red changes from pink, when it enters into ABS micelles, to yellow, when the ABS is degraded, and does not form micelles. When neutral red-tris(hydroxymethyl)-aminomethane buffer solution and then cationic surfactant solution were sprayed onto the agar surface of ABS-nutrient agar cultures, transparent haloes appeared around the colonies of ABS-degrading microorganisms against a pink background. Viable counts of ABS-degrading bacteria isolated from both seawater and freshwater environments were considerably higher in polluted waters than in less polluted areas. Viable counts of ABS-degrading bacteria averaged 1.5 x 105/ml in samples from the surface water of polluted Tokyo Bay and 3.0 x 104/ml in samples from the surface water of polluted Tamagawa River but were fewer in number in samples from less polluted waters.

Aerobiosis↗
PubMed1997

Relevance and applicability of a simple earthworm biomarker of copper exposure. II. Validation and applicability under field conditions in a mesocosm experiment with Lumbricus rubellus.

Earthworms Lumbricus rubellus were exposed to a range of increasing soil copper concentrations in a mesocosm experiment for 17, 40, 70, and 110 days, respectively. Neutral-red retention times were measured along with earthworm tissue copper residues and earthworm growth and survival. The neutral-red retention assay demonstrated a clear dose-response threshold preceding a copper exposure value where increased regulatory activity had resulted in the copper bioconcentration factor (BCF) decreasing from 1 to 0.5. Effects on earthworm growth and survival occurred only at soil copper concentrations where the earthworm BCFs were lowered to ca. 0.5. Thus, the position of the neutral-red threshold could potentially make it possible to differentiate between copper exposure and actual toxicity. In terms of field applicability it was demonstrated that natural and seasonal variations in climatic parameters had little or no effect on the neutral-red response. Neutral-red retention assay has a potential role in environmental risk assessment and routine monitoring, as it is likely to provide a sufficiently accurate warning of impending ecological damage at a level below that found to cause actual physiological damage to the earthworms.

Analysis of Variance↗
PubMed1984

Proton movements and electric potential generation in reconstituted ATPase proteoliposomes from the thermophilic cyanobacterium Synechococcus 6716.

ATP hydrolysis-induced proton translocation and electric potential generation have been studied in ATPase proteoliposomes by means of various optical probes. The proteoliposomes consisted of reconstituted ATPase complex and native lipid mixture isolated from the thermophilic cyanobacterium Synechococcus 6716 [Van Walraven et al. (1983) Eur. J. Biochem. 137, 101-106]. The native cartenoids and added oxonol VI served as probes for the electric membrane potential generated by the net charge separation (negative outside, positive inside). Their responses, with similar half-times as 9-tetradecylamino-6-chloro-2-methoxyacridine, are sensitive to valinomycin and stimulated by nigericin, as expected. The proton concentrations of extraliposomal and intraliposomal aqueous spaces were monitored by neutral red and cresol red; for internal measurements these pH indicators were trapped inside the vesicles during detergent dialysis. Internal acidification and external alkalinization induced by ATP hydrolysis are inhibited by nigericin and enhanced by valinomycin; at the commonly used higher valinomycin concentrations the neutral red response becomes transient, while the much slower cresol red response is diminished right from its onset. At smaller preset pH gradients both ATP hydrolysis activity and neutral red response are diminished. At increasing MgCl2 concentrations the neutral red responses are slowed down and the cresol red responses are slightly enhanced; this is observed for both internal and external dye responses. Neutral red permeation through the membrane is insignificant under our experimental conditions but is enhanced at temperatures below the lipid-phase transition. In the case of externally added neutral red the non-permeant buffer Hepes is only effective at high MgCl2 concentration, whereas some external cresol red response is visible only at high MgCl2 concentration in the presence of Hepes. The kinetics of the pH indicator and electric potential probe responses clearly distinguish fast interfacial and intra-membrane proton displacements from slow bulk proton equilibration. The data are summarized in a model that supports the importance of localized proton displacements for the primary energy-transducing events.

Adenosine Triphosphatases↗
PubMed1990

Cation selectivity of and cation binding to the cGMP-dependent channel in bovine rod outer segment membranes.

The properties of the cGMP-dependent channel present in membrane vesicles prepared from intact isolated bovine rod outer segments (ROS) were investigated with the optical probe neutral red. The binding of neutral red is sensitive to transport of cations across vesicular membranes by the effect of the translocated cations on the surface potential at the intravesicular membrane/water interface (Schnetkamp, P. P. M. J. Membr. Biol. 88: 249-262). Only 20-25% of ROS membrane vesicles exhibited cGMP-dependent cation fluxes. The cGMP-dependent channel in bovine ROS carried currents of alkali and earth alkali cations, but not of organic cations such as choline and tetramethylammonium; little discrimination among alkali cations (K greater than Na = Li greater than Cs) or among earth alkali cations (Ca greater than Mn greater than Sr greater than Ba = Mg) was observed. The cation dependence of cGMP-induced cation fluxes could be reasonably well described by a Michaelis-Menten equation with a dissociation constant for alkali cations of about 100 mM, and a dissociation constant for Ca2+ of 2 mM. cGMP-induced Na+ fluxes were blocked by Mg2+, but not by Ca2+, when the cations were applied to the cytoplasmic side of the channel. cGMP-dependent cation fluxes showed a sigmoidal dependence on the cGMP concentration with a Hill coefficient of 2.1 and a dissociation constant for cGMP of 92 microM. cGMP-induced cation fluxes showed two pharmacologically distinct components; one component was blocked by both tetracaine and L-cis diltiazem, whereas the other component was only blocked by tetracaine.

Animals↗
PubMed1991

Optical measurements of Na-Ca-K exchange currents in intact outer segments isolated from bovine retinal rods.

The properties of Na-Ca-K exchange current through the plasma membrane of intact rod outer segments (ROS) isolated from bovine retinas were studied with the optical probe neutral red. Small cellular organelles such as bovine ROS do not offer an adequate collecting area to measure Na-Ca-K exchange currents with electrophysiological techniques. This study demonstrates that Na-Ca-K exchange current in bovine ROS can be measured with the dye neutral red and dual-wavelength spectrophotometry. The binding of neutral red is sensitive to transport of cations across the plasma membrane of ROS by the effect of the translocated cations on the surface potential of the intracellular disk membranes (1985. J. Membr. Biol. 88: 249-262). Electrogenic Na+ fluxes through the ROS plasma membrane were measured with a resolution of 10(5) Na+ ions/ROS per s, equivalent to a current of approximately 0.01 pA; maximal electrogenic Na-Ca-K exchange flux in bovine ROS was equivalent to a maximal exchange current of 1-2 pA. Electrogenic Na+ fluxes were identified as Na-Ca-K exchange current based on a comparison between electrogenic Na+ flux and Na(+)-stimulated Ca2+ release with respect to flux rate, Na+ dependence, and ion selectivity. Neutral red monitored the net entry of a single positive charge carried by Na+ for each Ca2+ ion released (i.e., monitored the Na-Ca-K exchange current). Na-Ca-K exchange in the plasma membrane of bovine ROS had the following properties: (a) Inward Na-Ca-K exchange current required internal Ca2+ (half-maximal stimulation at a free Ca2+ concentration of 0.9 microM), whereas outward Na-Ca-K exchange current required both external Ca2+ (half-maximal stimulation at a free Ca2+ concentration of 1.1 microM) and external K+. (b) Inward Na-Ca-K exchange current depended in a sigmoidal manner on the external Na+ concentration, identical to Na(+)-stimulated Ca2+ release measured with Ca(2+)-indicating dyes. (c) The neutral red method was modified to measure Ca(2+)-activated K+ fluxes (half-maximal stimulation at 2.7 microM free Ca2+) via the Na-Ca-K exchanger in support of the notion that the rod Na-Ca exchanger is in effect a Na-Ca-K exchanger. (d) Competitive interactions between Ca2+ and Na+ ions on the exchanger protein are described.

Ammonia↗
PubMed1984

The role of the lysosome in natural killing: inhibition by lysosomotropic vital dyes.

Recent evidence has indicated the importance of lysosomes in natural killing (NK). The lysosomotropic dye neutral red, at concentrations greater than 2 X 10(-5) M, inhibits NK activity of large granular lymphocytes (LGL). Inhibition is at the level of effector cell activity rather than target cell susceptibility. Neutral red inhibits NK activity without affecting the viability of the effector cell population or the response of lymphocytes to the mitogen, phytohaemagglutinin (PHA). While the mechanism of this inhibition is unknown, neutral red-treated peripheral blood lymphocytes (PBL) do not suppress untreated effector cell populations. Furthermore, neutral red does not influence the binding of effector cells to target cells. Since natural killing by neutral red-treated PBL recovers slowly upon incubation of the cells at 37 degrees, inhibition is not due to selective toxocity. Trypan blue, another frequently used lysosomotropic vital stain, has no effect when effector cells are pretreated with 10(-3) M dye for 30 min or less. However, effector cells first treated with neutral red lose red granular staining following treatment with trypan blue for as little as 10 min at room temperature. Natural killing by neutral red pretreated PBL also recovers more quickly following brief incubation with trypan blue. Treatment of effector cells with trypan blue and neutral red simultaneously prevents accumulation of neutral red in cytoplasmic granules and subsequent inhibition of NK.

Cytoplasmic Granules↗
PubMed1995

Structure and immunogenicity of experimental foot-and-mouth disease and poliomyelitis vaccines.

The physico-chemical properties and immunogenicity of experimental vaccines against foot-and-mouth disease (FMD) and poliomyelitis, prepared by treatment of the viruses with N-acetylethyleneimine (AEI), formaldehyde or neutral red, have been studied. None of these reagents affects the rate of sedimentation of the particles or their reaction with antibody against the major immunogenic sites. FMD vaccines prepared by inactivation with AEI or neutral red, behaved like the untreated virus, in that they were disrupted on lowering the pH below 7. The RNA of the AEI-inactivated virus was degraded into slowly sedimenting molecules. Unlike AEI-inactivated virus, from which all the RNA could be extracted with phenol-SDS, the recovery from the neutral red inactivated virus was variable and was sometimes as low as 40%; this RNA gave a heterogenous profile in sucrose gradients. The capsid proteins in the AEI preparation migrated in SDS-PAGE to the same positions as those of untreated virus, but in the neutral red preparation there was evidence of cross-linking. In contrast, the formaldehyde-inactivated vaccine was stable below pH 7 and the RNA could not be released by extraction with phenol-SDS at pH 5, because the capsid proteins had become cross-linked and/or linked to the RNA. As with foot-and-mouth disease virus (FMDV), poliovirus which had been inactivated with formaldehyde did not release its RNA on extraction with phenol-SDS and the capsid proteins were also cross-linked. Surprisingly, although AEI cleaved the viral RNA slowly in situ, the virus was no longer infectious after 6 h. Neutral red did not reduce the infectivity of the virus. All of the preparations gave similar levels of neutralizing antibody after a single inoculation. The high levels obtained with the formaldehyde-inactivated vaccines have implications for the processing of fixed particles by the antigen-presenting cells.

Animals↗
PubMed2003

Optical enzyme sensor for urea determination via immobilized pH indicator and urease onto transparent membranes.

Transparent triacetylcellulose membranes with immobilized pH indicator (neutral red) as well as with simultaneously immobilized urease and neutral red were used as optical sensors for determination of urea concentrations in model solutions. Decomposition of urea with the enzyme urease is accompanied by evolution of ammonia. This leads to the changes of the neutral red absorption, which is proportional to the substrate (urea) within certain concentration limits in model solution. As a result of the investigation, standard curves were plotted for determination of urea over the range of 1 to 500 mM using immobilized indicator and free urease. Simultaneous immobilization of indicator and urease permitted determination of urea in the interval 50 to 500 mM. The membrane used contained 0.169 U urease activity on an area of 1.7 cm2. The standard curves were plotted using the linear region of the kinetic curves for the corresponding substrate concentrations. A possible scheme of the interaction between the activated triacetylcellulose membrane and the indicator and enzyme is proposed. The membranes obtained are suitable for repeated ecological applications where urea is to be determined.

Biosensing Techniques↗
PubMed2004

Simultaneous assay of glucose, lactate, L-glutamate and hypoxanthine levels in a rat striatum using enzyme electrodes based on neutral red-doped silica nanoparticles.

An electrochemical method suitable for the simultaneous measurement of cerebral glucose, lactate, L-glutamate and hypoxanthine concentrations from in vivo microdialysis sampling has been successfully performed for the first time using a neutral red-doped silica (NRDS) nanoparticle-derived enzyme sensor system. These uniform NRDS nanoparticles (about 50 +/- 3 nm) were prepared by a water-in-oil (W/O) microemulsion method, and characterized by a TEM technique. The neutral red-doped interior maintained its high electron-activity, while the exterior nano-silica surface prevented the mediator from leaching out into the aqueous solution, and showed high biocompability. These nanoparticles were then mixing with the glucose oxidase (GOD), lactate oxidase (LOD), L-glutamate oxidase (L-GLOD) or xanthine oxidase (XOD), and immobilized on four glassy carbon electrodes, respectively. A thin Nafion film was coated on the enzyme layer to prevent interference from molecules such as ascorbic acid and uric acid in the dialysate. The high sensitivity of the NRDS modified enzyme electrode system enables the simultaneous monitoring of trace levels of glucose, L-glutamate, lactate and hypoxanthine in diluted dialysate samples from a rat striatum.

Animals↗
PubMed1993

Extracellular calcium does not contribute to cryopreservation-induced cytotoxicity.

The possible role of extracellular calcium ([Ca+2]e) in cryopreservation-induced cytotoxicity was tested using Madin-Darby canine kidney (MDCK) cells and a fluorescent multiple endpoint assay. MDCK cells maintained in 2 mM [Ca+2]e and treated with the calcium ionophore, ionomycin, increased their intracellular calcium ([Ca+2]i) as revealed by the calcium indicator dye, Fluo3 and the bottom-reading spectrofluorometer, CytoFluor 2300. The addition of 10 mM [ethylene bis (oxyethylenenitrilo)]-tetraacetic acid (EGTA) to the extracellular medium before treatment with ionomycin blocked this ionomycin-dependent increase in [Ca+2]i. A number of site and activity-specific fluorescent probes were surveyed to determine which indicator dye might best reveal the ionomycin-induced cytotoxic events during this increase in [Ca+2]i. Although most dyes changed their emission profiles in response to calcium, neutral red was found to best reflect the loss of [Ca+2]i homeostasis. The NR50 for a 15-min exposure to ionomycin in the presence of 2 mM [Ca+2]e was approximately 2 microM ionomycin, but ionomycin had little apparent effect on neutral red retention when 10 mM EGTA was added to the extracellular medium. Thus it was clear that an increase in [Ca+2]i could be cytotoxic to MDCK cells and that neutral red could monitor this cytotoxic episode. To test if [Ca+2]e was similarly cytotoxic during cryopreservation, MDCK cells were subjected to cryopreservation in the presence of dimethylsulfoxide (DMSO). In contrast to previous studies, plasma membrane integrity, not lysosomal function, seemed to best correlate with cell survival subsequent to cryopreservation. In addition, decreasing [Ca+2]e had no discernable effect on the retention of plasma membrane indicator dyes, neutral red, or cell survival. It is concluded that a) plasma membrane indicator dyes, not neutral red, might be better indicators of cytotoxicity occurring during cryopreservation; b) DMSO might be toxic to lysosomes during cryopreservation of cultured cells; and c) although [Ca+2]e can contribute to cytotoxicity, the presence of [Ca+2]e might not influence cryopreservation-induced cytotoxicity.

Aniline Compounds↗