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Effects of biogenic and abiogenic disulphides on viability of human umbilical vein endothelial cells in culture has been investigated using three methods: the neutral red uptake assay, quantification of intracellular ATP, and modifications of Mosmann method, the essence of which is the reduction of tetrazolium salts, MTT and MTS, by cells. 2,2'-dithio-bis(N,N-diethyl)ethanamine (DS) was used as an abiogenic disulphide. As for biogenic disulphides, we used GSSG and garlic oil (GO), the principal component of which is diallyl disulphide (DADS). It has been found that DS and GO have a similar cytotoxic effect upon the endothelial cells (EC50 - 0.6 mM). GSSG in concentrations up to 1 mM did not effect the viability of endothelial cells. It has been demonstrated for the first time that DS and GO can serve as mediators of plasma membrane oxidoreductase activity, tetrazolium salts being as the substrate; this may cause false-negative effect. Thus, the Mosmann method has serious limitations when testing the cytotoxicity of disulphides, though can be used in studying the mechanism of action of disulphides.

After removal of parotid glands in 104 white rats, the gastric acidity increased and excretion of neutral red occurred. Simultaneously the kallikrein activity and kallikreinogen concentration as well as concentration of kininogen became enhanced whereas the bradykinin of plasma decreased. The data suggest that the mechanism of activation of the stomach secretory and excretory functions after removal of parotid glands involves inactivation of the blood kallikrein system.

Effects of energy metabolism inhibitors on the granule formation of neutral red in Ehrlich ascite carcinoma cells have no relation with the action of these agents on the ATP formation. Accumulation of neutral red by cells has no relation with granule formation and does not depend on the energy metabolism of cells. The action of 2,4-dinditrophenol, oligomycin, Tween-20, Tween-80 and sodium deoxycholate on the granule formation may be linked with direct action of these agents on the cell membranes, for example, on the Golgi membranes.

Growing chloronema and rhizoid cells of the intact protonema of Funaria hygrometrica absorb luminescent stains selectively. The cation stains--acridine orange and neutral red, at pH 5.0 are absorbed by growing tips of the apical cells. The anion stain (uranine) is absorbed by the basal end of the apical cells and by intercalary cells of the protonema filaments. Red light inactivates the cell permeability to the cation and anion stains. Far-red light partly reversed the action of the red light solely on the initial stages of the irradiation. During the red light induced branching of apical cells the cation stains enter the cells through a new originated growing point.

Evidence on the influence of Ca2+ on the binding of neutral red by plasma membranes of skeletal muscle is dealt with. It is suggested that the binding of Ca2+ occurs according to the principle of bimolecular binding. It is suggested that the Ca2+-binding sites with high affinity may control the process of calcium transport by plasma membranes.

The frog cornea epitelial cells, nervous cells of spinal ganglia and of urinary bladder have been found to survive in vitro, in the presence of subtoxical concentrations of chloral hydrate, urea, ethanol or methanol added to the Ringer solution, longer than control preparations. The above drugs added both in lower and higher concentrations lead to cell damages, thus reducing the cell survival time, which was tested by the capacity to deposit granules of a vital dye - neutral red.

Effects of metabolites of the tiny fungi of Aspergillus flavus and A. niger on the ability of mucuos membrane cells of the large intestine to absorb and exterminate certain dyes has been studied experimentally on guinea-pigs. It has been shown that under these influences, a violation of the cell and tissue metabolism in the large intestine occurs, namely, the absorbtion of the neutral red increased by 1.7 and 1.4 times, respectively, and the processes of extermination of the cells were inhibited by 1.5--1.6 times.

Experiments on dogs were made to perform bilateral adrenalectomy and substitution therapy with hydrocortisone. Juice and acid secretion and neutral red excretion were found to be lowered after stimulation of secretion by meat and histamine. Excretion of ammonia after meat stimulation decreased, while after histamine administration it remained unchanged.

Kinetics of Neutral red (NR) and Acridine orange (AO) uptake by cultured L cells (subline LSM) has been studied. It was found that the uptake of both NR and AO, with their constant concentrations in the medium was characterized as a two-phase process. During 2 hours, these cells concentrated as much as 90% of the total amount of NR and AO taken up during the whole incubation period. The segregation and accumulation of NR, AO as well as NH4Cl took place in lysosomes. NR and AO concentrations within the cells exceed by 600 and 400 times, respectively, those in the medium. NR, AO and NH4+ accumulation in cells resulted in inhibition of the activity of the following lysosomal hydrolases: cathepsins B and D, acid lipase, N-acetyl-beta,D-glucosaminidase, beta-galactosidase, acid phosphatase and galactosyltransferase, the latter being a marker of Golgi apparatus. The effect of lysosomal enzyme activity inhibition on the cell economy, and a possible role of lysosomotropic agents as regulators of the lysosomal apparatus functional activity are discussed.

Studies of the equilibrium distribution of the cation dye-neutral red by actomyosin threads allowed to establish the fact that different concentrations of dye reveal the existence of different bonds with contractile proteins. Firm bonds (7.3 ccal/M) are discovered at low dye concentrations, and weaker bonds (4.5 ccal/M) are seen at higher concentrations. The contraction of actomyosin threads evoked by ATP or heating is accompanied with similar changes, i. e. by the diminishing of the maximum dye sorption within the range of low dye concentrations and by the increase in the maximum dye sorption within the range of high concentrations.

A method of pH determination in the cytoplasm and individual lysosomes of intact living cultured cells is proposed using an indicator dye--neutral red (NR). The pH value of an investigated structure stained with NR is from the ratio between its optical densities at two wave lengths, the one corresponding to the isobestic point (lambda = 470 nm), and the other--to the absorption maximum of the neutral form of the dye (lambda = 450 nm). This method enabled us to make pH determination in the range from 4.5 to 7.2; the accuracy of the method reaches +/- 0.36 at pH 4.7 and diminishes to +/- 0.16 at pH much greater than 5.5. Using this method for the culture of pig kidney embryonal cells and Chinese hamster fibroblasts a heterogeneity of lysosomes was found with respect to the average pH value, oscillating ultradian changes in intralysosomal pH values, and the relationship between the changes and the size and average pH values of lysosomes. It is shown that the accumulation of NR in lysosomes depends on the pH gradient between lysosomes and the cytoplasm, which diminishes with the development of non specific cell response under the influence of some agents) high NR concentrations, inhibitor of glycolysis, or uncouplers of oxidative phosphorus lotion).

The data on the ultra-violet (UV) rays effect on the sorptional properties of rats liver, kidneys and heart tissues showing the different functions of internals tissues in the animal's reactions to the UV-radiation are given.

A study of the effect of uncouplers of the oxidative phosphorylation on the interaction on neutral red with the normal mouse fibroblast and tumour L-cells showed the former to retain the capacity for the dye granule formation in the presence of 1x10 4 M 2,4-dinitrophenol (DNP). Another uncoupler of the oxidative phosphorylation - n-trifluoromethoxycarbonycyanidephenylhydrazone (FCCP) depressed the granule formation both in the tumour L-cells and in the mouse normal fibroblasts. The dye uptake in the normal fibroblasts and in the tumour L-cells was inhibited by both the DNP and the FCCR in the concentration which uncoupled the oxidative phosphorylation.

The conditions of the passage of neutral red into the cavity of gastro--intestinal tract were investigated during the atropine blockade of the stomach secretory activity in the dogs with fundal, antral and duodenal fistulas. The neutral red begins to cross the gastric mucosa only after the PH of the perfusing solution has achieved 2.5 and for intestine--5.0. The intensity of the neutral red passage increases with further decrease of the perfusing solution pH. During perfusion of acid solutions through the stomach and particularly through the duodenum, retrodiffusion of H+ occurs into the mucosa. The excretion of neutral red into the cavity of gastro--intestinal tract seems to be a process of passive diffusion. The role of the H+ retrodiffusion in this process is discussed.

Granules arising in the cytoplasm of Rana temporaria erythrocytes incubated in solutions containing either a stain (neutral red) or an alcaloid (novocaini) were studied cytophotometrically. The stuff concentrations in the granules were estimated under various conditions of incubations. The stuff concentrations in the granules appeared to be dozens- or hundreds--fold higher than in the incubation solutions. The average concentration in the granules did not depend either on the initial concentration of the stuff solution, or on the incubation time or on the volume of the incubation solution. The stuff concentration in the granule decreases with the increase in the granule size.