Cell Membrane Polarization Research Articles

Cell membrane polarity in rat ascites hepatoma cells. Distribution of a cell surface-associated adhesive factor on the cell surfaces.

As previously described, a cell surface-associated adhesive factor (AF) was separated from differentiated rat ascites hepatoma AH136B cells (forming cell islands in vivo) and highly purified by chromatography. AF induces not only aggregation of dissociated AH136B cells or undifferentiated rat ascites hepatoma AH109A cells (present as free cells in vivo), but also adhesiveness characterized by the development of junctional complexes. The localization of AF on the surfaces of AH136B cell islands was investigated using anti-AF IgG (Fab fragment) coupled to peroxidase. AF was detected in the contact region of the lateral surfaces of the AH136B cells and in the intercellular spaces. In contacted free cell surfaces of AH136B cells. Fluorescence studies revealed that biotin-labeled AF did not bind to the apical surface of AH136B cell islands. These results indicate a distinct difference between apical and lateral surfaces of AH136B cells; neither AF nor binding site for AF were localized on the apical surface of AH136B cells, whereas both were localized on the lateral surface. On the other hand, AH136B cells detached from the cell islands, or during the process of partial dissociation from them, showed the loss of the AF localization and binding site of AF on the surfaces. The results suggest that AH136B cell surfaces may be polarized in terms of the AF localization, and this polarization may be lost after cell dissociation.

Effect of ethanol and aging on histamine release and membranes of mast cells

The effects of ethanol on histamine release from mast cells were compared to ethanol's effects on membrane order of mast cell membranes and synaptosomes in young (6 month) and old (24 month) Fischer 344 rats. Concanavalin A (con A) stimulated histamine release in a concentration dependent manner. Ethanol (10–500 mM) inhibited con A stimulated release while having no effect on nonstimulated release in both young and old rats. Ethanol's effect on membrane order of synaptosomes and mast cell plasma membranes was estimated by measuring the fluorescence polarization of diphenylhexatriene. Ethanol (10–500 mM) decreased the polarization of synaptosomes to the same degree in young and old rats. The polarization of mast cell membranes was also decreased by ethanol but to a greater degree than synaptosomes. The ethanol induced changes in polarization correlated (r 2=0.99) with ethanol's inhibition of con A stimulated histamine release from mast cells. These findings suggest that mast cells may be more sensitive to membrane disordering by ethanol than synaptosomes. In addition, we have demonstrated that mast cells may be a useful model system for studying ethanol effects on stimulus-secretion coupling. No differences were found between rats 6 and 24 months for histamine release (with or without ethanol) or membrane order of mast cells or synaptosomes.

Cell membrane polarity in primary human fibroblasts

The topologies of bindings of cationized CF and native ferritin (NF) on plasma membranes of primary human fibroblasts were examined by transmission electronmicroscopy. Both ligands bound mainly to apical surfaces and less abundantly to lateral regions. At basal localization they were observed only at cell-to-cell connections. The polarity of negatively charged binding sites was not altered by glutaraldehyde fixation. The definite polarity of plasma membranes of cultured cells express alternating surface areas charged negatively or positively.

Dielectric characteristics of packed human erythrocytes with haemoglobins F, AA, AS and SS

The radiofrequency dielectric behaviour of packed human erythrocytes has been investigated in normal haemoglobins F and AA and also abnormal haemoglobins homozygous SS and heterozygous AS. Dielectric measurements were made in tightly packed blood cells at an average room temperature of 26.5 +or-0.5 degrees C in the frequency range from 0.1 to 100 MHz. In agreement with previous findings in many biological molecules, all the packed erythrocytes of the different haemoglobins exhibited a decrease in dielectric constant and an increase in conductivity with frequency. However, each type has been found to show distinct dielectric dispersion with respect to the others and this has been associated with their molecular structure in addition to the polarization of cell membrane. The possible application of this technique in identifying different haemoglobins of the blood has been suggested.

Cell Membrane Polarity in Dissociated Frog Urinary Bladder Epithelial Cells 12.

Localization of cell membrane markers in dissociated frog urinary bladder epithelial cells was studied. The bladder cells began to alter in shape immediately after dissociation and became spherical within 15 min at room temperature. The apical marker, dialyzed iron (DI), was found on the entire surface of dissociated and transformed cells, whereas the basolateral marker, horseradish peroxidase-glutaral-dehyde (HRP-GLA) staining, first gathered at one pole and then became distributed over a larger area. Thus the apparent loss of polarity was not parallel with the true surface uniformity. When bladder cells were dissociated in the presence of cytochalasin B (CB) or 2,4-dinitrophenol (DNP), the transformation was suppressed and the cells maintained structural polarity. DI and HRP-GLA were mostly confined to the original region in CB-treated cells, but both moved to the other membrane region in DNP-treated cells. The results indicated that an aerobic adenosine triphosphate supply, as well as the tight junction, is involved in maintaining regional differentiation of the cell membrane.

19F-NMR and fluorescence polarization of yeast plasma membrane and isolated lipids

Summary 16-Fluoropalmitic acid was incorporated biosynthetically into the plasma membrane of yeast and the F-NMR spectra of the intact membrane and of aqueous dispersions of membrane lipids were compared. The greater degree of resonance broadening in the intact membrane reveals a lesser degree of mobility of the acyl chains. Fluorescence polarization studies with a probe that monitors the polar environment and one that detects viscosity changes in the inner core of the bilayer indicate hindered motions of the polar head groups and acyl chains in the intact membrane as compared to liposomes prepared from membrane lipids. The observations indicate that the bulk of lipids in the yeast membrane experiences immobilization by proteins and that membrane proteins influence lipid-lipid interactions and inhibit lipid phase transition.

Pars intermedia electrical potentials: changes in spike frequency induced by regulatory factors of melanocyte stimulating hormone (MSH) secretion.

Spontaneous action potentials recorded from pars intermedia (PI) cells of frog pituitaries are correlated with spontaneous melanophore stimulating hormone (MSH) secretion from that gland. Those agents known to induce hormone release (e.g., serotonin, isoproterenol) increase the rate of electrical activity, whereas those which inhibit secretion (e.g., norepinephrine, dopamine, GABA) reduce the frequency of spikes. MSH secretion appears to involve cellular depolarization while inhibition of release is associated with cell membrane polarization.

The bimodal basis of the contractile response of the rabbit ear artery to norepinephrine and other agonists

Strips of rabbit ear artery exhibit biphasic contractile responses to l-norepinephrine (1-NE), histamine, and serotonin. Evidence is presented on the basis of an analysis of the response to 1-NE that the two phases of contraction are associated with different modes of excitation and can be influenced independently. The initial part of the response is phasic. The response after 4 sec agonist exposure is the same as that after 32 sec. It is probably associated with local radial propagation of excitation in that the initial excitatory period is short, the contraction is preceded by electrical change and is abolished upon tissue exposure to a solution in which all NaCl and KCl is replaced by potassium methylsulfate. In contrast the second contractile phase is related to the time of tissue exposure to the drug, is an equilibrium-like response and is not dependent upon cell membrane polarization. Since this phase is more affected by calcium depletion than the first, the sources of activator calcium for the two phases may be different: that for the first phase many originate predominantly from intracellular and that for the second from extracellular sources. These findings support the hypothesis that the biphasic contractile response of the vessel reflects two different modes of excitation of the muscle wall by the agonists: the first, a triggered, propagated event; the second, a slow, equilibrium-type, non-propagated response.

Nuclear Membranes and Plasma Membranes from Hen Erythrocytes: I. ISOLATION, CHARACTERIZATION, AND COMPARISON

The bird erythrocyte provides a cell system which comprises only two sorts of membranes, namely the plasma membrane and the nuclear envelope. As calculated morphometrically, both of these membranes are present in an almost 1:1 membrane surface ratio. Contamination with other types of membranes is a priori excluded in this cell. Purified fractions of plasma membranes and nuclear envelope membranes were isolated by using nondetergent methods, in which high speed rotating knife homogenization is combined with differential and gradient centrifugation steps. Nuclear membranes were separated from other nuclear constituents after high salt extraction of nucleoproteins and sonic oscillation, with or without an additional digestion with DNase. Purity and structural integrity of the fractions are shown in electron micrographs. The buoyant densities of nuclear membranes (p422 = 1.20) and plasma membranes (p422 = 1.14) are different. The gross compositions of intact cells and the nuclei, nuclear membrane, and plasma membrane fractions, with respect to lipids, phospholipids, cholesterol, protein, RNA, and DNA, are given, as well as corresponding recoveries. The nuclear membrane is distinct from the plasma membrane as shown in a much lower cholesterol-phospholipid ratio, in a higher content in protein, and a certain amount of DNA remaining firmly attached to it. In general, the properties of the bird erythrocyte plasma membrane agree with those known from the non-nucleated erythrocytes. Among the enzymes examined, the plasma membrane showed ATPase activity, including a ouabain-sensitive one. On the other hand, the nuclear membrane fraction was almost devoid of ATPase activity, but did show the activity of a typical endoplasmic reticulum type enzyme, the NADH-cytochrome c reductase. While the nuclear fraction demonstrated a strong enrichment for NAD+ pyrophosphorylase, this activity was not found in the plasma membranes or in the nuclear membranes, which indicates the low degree of nucleoplasmic protein contamination present in the nuclear membrane fraction. The differences between the only two membrane systems of this dead end differentiated cell type are discussed in context with the present concepts on the cytomembrane → plasma membrane polarization and diversity.

A note on transmembrane potential in dermal melanophores of the frog and movement of melanin granules.

1. Transmembrane potentials were measured and distribution of melanin granules observed in dermal melanophores of the isolated frog's web.2. In normal Ringer solution, melanin granules were aggregated in the cell bodies and the transmembrane potentials were usually in the range 70-90 mV.3. Addition of alpha-melanocyte stimulating hormone (alpha-MSH) to the bathing solution resulted in dispersion of the melanin granules into the processes of the cells, without any accompanying change in membrane potentials. Altering the membrane potentials by changing the external K(+) concentration had no effect on melanin migration.4. It is concluded that migration of melanin granules in these cells is unrelated to cell membrane polarization.

The transitional phenomenon in contraction of uterine muscle.

1. A series of contraction in Krebs solution by repeated electrical stimulation to the progesterone-dominated rabbit uterus in vitro, was named as the transitional phenomenon and its mechanism was investigated. 2. The phenomenon was classified into 4 types and type A is taken as to be the. most typical. 3. The phenomenon can be devided into three stages and contractions of the 1st and 2nd stage were different in shape from the 3rd stage. 4. The phenomenon was affected by preservation of the muscle and finally disappeared. 5. Uterine horn showed the most typical phenomenon to the rest of the uterus and could hold it for a longer period of time. 6. The phenomenon was observed only once in a same strip of uterus. 7. The temperature of Krebs solution in experiment was the most suitable at 28°C to obtain it. Rising the temperature to 37°C obscured its appearance. 8. The optimal voltage for the phenomenon was 2 V/cm and 8 V/cm or more disappeared it. 9. The phenomenon was seen in both of longitudinal and transverse applications of electrical stimulation. 10. The phenomenon could not be observed when the muscle was depolarized below the certain level by excess K ion. 11. The phenomenon was least sensitive to the alteration of Ca ion in Krebs solution. 12. Hypertonic and hypotonic Krebs solutions disappeared it. 13. The phenomenon was closely dependent on interval and duration of the electrical stimulation. 14. From these data, the main cause of the transitional phenomenon is speculated as the shift of polarization of cell membrane. But decrement of both metabolism and conduction property in muscle cell by progesterone also ought to be considered.