Effect of paeoniflorin and menthol on membrane fluidity, Na⁺-K⁺-ATPase activity and Ca²⁺-ATPase activity during transport of puerarin in Calu-3 cell / 中国中药杂志

The aim of this research is to investigate the effects of paeoniflorin and menthol on the physiological function of Calu-3 cell membrane during the transport of puerarin. Calu-3 cell was used as the cell model to simulate nasal mucosa tissues, and the cell membrane fluidity, Na⁺-K⁺-ATPase activity and Ca²⁺-ATPase activity were detected by fluorescence recovery after photobleaching(FRAP) and ultramicro enzyme activity testing, in order to explore the mechanism of compatible drugs on promoting puerarin transport. The results showed that when puerarin associated with low, middle and high concentration of menthol or both paeoniflorin and menthol, the fluorescence recovery rate was increased significantly, while Na⁺-K⁺-ATPase activity had no significant change and Ca²⁺-ATPase activity was enhanced significantly as compared with puerarin alone. Therefore, it was concluded that menthol had the abilit of promoting the transport and the mechanism might be related to increasing membrane fluidity and activating Ca²⁺-ATPase.

Effect of phosphorus deficiency on erythrocytic morphology and function in cows

The aim of this study was to evaluate the influence of phosphorus (P) deficiency on the morphological and functional characteristics of erythrocytes in cows. Forty Holstein-Friesian dairy cows in mid-lactation were randomly divided into two groups of 20 each and were fed either a low-P diet (0.03% P/kg dry matter [DM]) or a control diet (0.36% P/kg DM). Red blood cell (RBC) indices results showed RBC and mean corpuscular hemoglobin decreased while mean corpuscular volume increased significantly (p < 0.05) in P-deficient cows. Erythrocyte morphology showed erythrocyte destruction in P-deficient cows. Erythrocytes' functional characteristics results showed total bilirubin and indirect bilirubin concentrations and aspartate transaminase and alanine transaminase activity levels in the serum of P-deficient cows were significantly higher than those in control diet-fed cows. Activities of superoxide dismutase and glutathione peroxidase in erythrocytes were lower, while the malondialdehyde content was greater, in P-deficient cows than in control diet-fed cows. Na⁺/K⁺-ATPase and Mg²⁺-ATPase activities were lower in P-deficient cows than in control diet-fed cows; however, Ca²⁺-ATPase activity was not significantly different. The phospholipid composition of the erythrocyte membrane changed and membrane fluidity rigidified in P-deficient cows. The results indicate that P deficiency might impair erythrocyte integrity and functional characteristics in cows.

Mitochondrial ATPase activity and membrane fluidity changes in rat liver in response to intoxication with Buckthorn (Karwinskia humboldtiana)

BACKGROUND: Karwinskia humboldtiana (Kh) is a poisonous plant of the rhamnacea family. To elucidate some of the subcellular effects of Kh toxicity, membrane fluidity and ATPase activities as hydrolytic and as proton-pumping activity were assessed in rat liver submitochondrial particles. Rats were randomly assigned into control non-treated group and groups that received 1,1.5 and 2 g/Kg body weight of dry powder of Kh fruit, respectively. Rats were euthanized at day 1 and 7 after treatment. RESULTS: Rats under Kh treatment at all dose levels tested, does not developed any neurologic symptoms. However, we detected alterations in membrane fluidity and ATPase activity. Lower dose of Kh on day 1 after treatment induced higher mitochondrial membrane fluidity than control group. This change was strongly correlated with increased ATPase activity and pH gradient driven by ATP hydrolysis. On the other hand, membrane fluidity was hardly affected on day 7 after treatment with Kh. Surprisingly, the pH gradient driven by ATPase activity was significantly higher than controls despite an diminution of the hydrolytic activity of ATPase. CONCLUSIONS: The changes in ATPase activity and pH gradient driven by ATPase activity suggest an adaptive condition whereby the fluidity of the membrane is altered.

Effect of terpene penetration enhancer and its mechanisms on membrane fluidity and potential of HaCaT keratinocytes / 中国中药杂志

The aim of this paper was to investigate the effect of terpene penetration enhancers on membrane fluidity and membrane potential using HaCaT keratinocytes, and study the potential mechanisms of these terpene compounds using as natural transdermal penetration enhancer. Six terpene compounds, namely menthol, limonene, 1,8-cineole, menthone, terpinen-4-ol and pulegone, were chosen in this study on account of their good penetration-enhancement activities. The cytotoxicity of these terpene compounds was measured using an MTT assay. The fluorescence recovery after photobleaching (FRAP) technique was employed to measure the change of membrane fluidity of HaCaT cells. The flow cytometer was used to study the alteration of membrane fluidity of HaCaT cells, and investigate the effect of terpene compounds on intracellular Ca2+. It was found that 6 terpene compounds possessed low cytotoxicity in comparison to the well-established and standard penetration enhancer azone. Those terpene compounds could significantly enhance HaCaT cells membrane fluidity and decrease HaCaT cells membrane potentials. Meanwhile, after treated with various terpene compounds, the Ca2(+)-ATPase activity and intracellular Ca2+ of HaCaT cells was decreased significantly. Terpene penetration enhancers perhaps changed the membrane fluidity and potentials of HaCaT cells by altering the Ca2+ balance of the cell inside and outside, resulting in the low skin permeability to increase the drug transdermal absorption.

Study on membrane injury mechanism of total alkaloids and berberine from Coptidis Rhizoma on Aeromonas hydrophila / 中国中药杂志

To explore the antibacterial activity and mechanism of total alkaloids and berberine from Coptidis Rhizoma on Aeromonas hydrophila, and determine the effect of total alkaloids and berberine from Coptidis Rhizoma on minimum inhibitory concentrations, permeability and fluidity of cell membrane, conformation of membrane proteins and virulence factors of A. hydrophila. The results showed that both total alkaloids and berberine from Coptidis Rhizoma had antibacterial activities on A. hydrophila, with minimum inhibitory concentrations of 62.5 and 125 mg · L(-1), respectively. Total alkaloids and berberine from Coptidis Rhizoma could increase the fluidity of membrane, change the conformation of membrane porteins and increase the permeability of bacteria membrane by 24.52% and 19.66%, respectively. Besides, total alkaloids and berberine from Coptidis Rhizoma significantly decreased the hemolysis of exotoxin and the mRNA expressions of aerA and hlyA (P < 0.05, P < 0.01), the secretion of endotoxin and the mRNA expression of LpxC (P < 0.05, P < 0.01). The results suggested that the antibacterial activity of total alkaloids and berberine from Coptidis Rhizoma on A. hydrophila may be related to the bacteria membrane injury. They inhibited the bacterial growth by increasing membrane lipid fluidity and changing conformation of membrane proteins, and reduced the secretion of virulence factors of A. hydrophila to weaken the pathogenicity.

Influence of cationic cyclopeptide on microstructure and permeability of Caco-2 cell membrane / 药学学报

The microstructure of cationic cyclopeptide (TD-34) treated Caco-2 cell membrane was observed, and we discussed the relationship between membrane structure and insulin transmembrane permeability. Atomic force microscope (AFM) was used to observe living cell membrane in air condition and tapping mode. Results showed that the surface of Caco-2 cell membrane treated with TD-34 lost its smoothness and nearly doubled its roughness. Apparent permeability coefficients (P(app)) of insulin in Caco-2 cell monolayers increased 2.5 times. In conclusion, AFM can be used to observe microstructure of cationic cyclopeptide treated cell membrane and cationic cyclopeptide enhanced insulin delivery across Caco-2 cell membrane by increasing membrane fluidity.

Caracterização da superexpressão do fator sigma ECF σx em Pseudomonas aeruginosa PA14 / Characterization ofthe ECF sigma fator σx overexpression in Pseudomonas aeruginosa PA14

Pseudomonas aeruginosa é uma proteobactéria do grupo gama muito versátil, capaz de colonizar ambientes variados e infectar hospedeiros filogeneticamente distintos, incluindo humanos imunocomprometidos. Os fatores sigma de função extracitoplasmática (ECF) são membros de sistemas de sinalização de superfície celular (CSS), abundantes em P. aeruginosa. Vinte genes codificando fatores sigma ECF estão presentes nos genomas sequenciados de P. aeruginosa, a maioria fazendo parte de sistemas TonB relacionados à captação de ferro. Neste trabalho, seis fatores sigma pobremente caracterizados foram superexpressos na linhagem PA14 a partir de um promotor induzível por arabinose para investigar seu papel na expressão dos sistemas de dois componentes PvrSR e RcsCB, que atuam na regulação da fímbria CupD, além de sua influência no crescimento de culturas de P. aeruginosa. Não foi observado efeito positivo de nenhum dos fatores sigma testados na expressão dos sistemas de dois componentes e a superexpressão de cinco deles tampouco levou a qualquer alteração no crescimento, porém a produção de piocianina foi alterada na superexpressão de PA14_55550 e a superexpressão de PA14_26600 e PA14_46810 levou a um discreto aumento no início da formação de biofilme em PA14. Por outro lado, culturas superexpressando σx (ALB04) apresentaram um perfil alterado de lipopolissacarídeo e uma curva de crescimento bifásica, alcançando precocemente uma fase estacionária seguida de uma recuperação do crescimento até uma segunda fase estacionária. Durante a primeira fase estacionária, a maior parte das células aumenta de tamanho e morre, mas as células remanescentes retornam à morfologia selvagem e seguem para a segunda fase de crescimento exponencial. Isso não acontece devido a mutações compensatórias, uma vez que células coletadas de pontos tardios da curva e diluídas em meio novo repetem este comportamento. Apesar de trabalhos com a linhagem PAO1 associarem σx à transcrição de oprF, que codifica a principal porina não específica de Pseudomonas, nas condições dos nossos ensaios em PA14 a expressão dessa porina não foi induzida pela superexpressão de σx. Assim, os efeitos observados nessa superexpressão também não podem ser atribuídos a OprF. A transcrição de oprF em PA14 mostrou-se majoritariamente dependente da região promotora a que se atribui a ligação de σ70, ao contrário dos relatos na literatura da dependência da região de ligação a σx. Análises proteômicas foram realizadas para investigar os elementos envolvidos nesses efeitos de superexpressão de σx, o que revelou a indução de diversas enzimas envolvidas na via de biossíntese de ácidos graxos. As células superexpressando σx apresentam uma maior proporção de ácidos hexadecanoico (C16) e hexadecenoico (C16:1) e dados de anisotropia mostram uma maior fluidez da(s) membrana(s). Este trabalho é o primeiro relato de um fator sigma ECF envolvido em biossíntese de lipídeos em P. aeruginosa

Pseudomonas aeruginosa is a very versatile gammaproteobacteria, able to colonize different environments and to infect phylogenetically distinct hosts, including immunocompromised humans. The extracytoplasmic function sigma factors (ECFs) are members of cell signaling systems (CSS), abundant in P. aeruginosa. Twenty genes coding for ECF sigma factors are present in the sequenced genomes of P. aeruginosa, most of them being part of TonB systems related to iron uptake. In this work, six poorly characterized sigma factors were overexpressed in strain PA14 from an arabinose inducible promoter to investigate their role in the expression of the two-component systems PvrSR and RcsCB, which regulates CupD fimbria, and their influence in P. aeruginosa cultures growth. None of the tested sigma factors led to two-component systems upregulation and overexpression of five of them caused no change in the growth profile, but pyocyanin production was altered in PA14_55550 overexpression and PA14_26600 and PA14_46810 overexpression led to a slight increase in biofilm initiation in PA14. By the other side, cultures overexpressing σx (ALB04) presented an altered lipopolysaccharide profile and a biphasic growth curve, reaching an early stationary phase followed by a growth resuming untill a second stationary phase. During the early stationary phase, most cells swells and dies, but the remaining cells return to wild type morphology and proceed to the second exponential phase of growth. This is not due to compensatory mutations, since cells collected from late points of the curve and diluted in fresh medium repeat this behavior. Although studies with strain PAO1 associate σx with transcription of oprF, encoding the major nonspecific porin of Pseudomonas, under our experiments conditions with PA14, this porin expression is not induced by σx overexpression. Thus, the effects observed in this overexpression cannot be attributed to OprF. Transcription of oprF in PA14 proved to be mainly controlled by the σ70-dependent promoter region instead of the σx-dependent promoter region reported in the literature. Proteomic analyses were performed to investigate the elements involved in these effects of σx overexpression, which revealed the induction of several enzymes involved in fatty acids biosynthesis. Cells overexpressing σx exhibit a greater proportion of hexadecanoic (C16) and hexadecenoic (C16: 1) acids and anisotropy data show higher fluidity of the membrane (s). This work is the first report of an ECF sigma factor involved in lipid biosynthesis in P. aeruginosa

Electron paramagnetic resonance study of lipid and protein membrane components of erythrocytes oxidized with hydrogen peroxide

Electron paramagnetic resonance (EPR) spectroscopy of spin labels was used to monitor membrane dynamic changes in erythrocytes subjected to oxidative stress with hydrogen peroxide (H2O2). The lipid spin label, 5-doxyl stearic acid, responded to dramatic reductions in membrane fluidity, which was correlated with increases in the protein content of the membrane. Membrane rigidity, associated with the binding of hemoglobin (Hb) to the erythrocyte membrane, was also indicated by a spin-labeled maleimide, 5-MSL, covalently bound to the sulfhydryl groups of membrane proteins. At 2% hematocrit, these alterations in membrane occurred at very low concentrations of H2O2 (50 µM) after only 5 min of incubation at 37°C in azide phosphate buffer, pH 7.4. Lipid peroxidation, suggested by oxidative hemolysis and malondialdehyde formation, started at 300 µM H2O2 (for incubation of 3 h), which is a concentration about six times higher than those detected with the probes. Ascorbic acid and α-tocopherol protected the membrane against lipoperoxidation, but did not prevent the binding of proteins to the erythrocyte membrane. Moreover, the antioxidant (+)-catechin, which also failed to prevent the cross-linking of cytoskeletal proteins with Hb, was very effective in protecting erythrocyte ghosts from lipid peroxidation induced by the Fenton reaction. This study also showed that EPR spectroscopy can be useful to assess the molecular dynamics of red blood cell membranes in both the lipid and protein domains and examine oxidation processes in a system that is so vulnerable to oxidation.

Growth, fatty acid profile in major lipid classes and lipid fluidity of Aurantiochytrium mangrovei Sk-02 as a function of growth temperature

Aurantiochytrium mangrovei Sk-02 was grown in a medium containing glucose (40 g/l), yeast extract (10 g/L) and sea salts (15 g/L) at temperatures ranging from 12 to 35°C. The fastest growth (µmax= 0.15 h-1) and highest fatty acid content of 415 mg/g-dry cell weight were found in the cells grown at 30°C. However, the cells grown at 12°C showed the highest percentage of polyunsaturated fatty acid (PUFA) (48.6% of total fatty acid). The percentage of docosahexaenoic acid (DHA) and pentadecanoic acid (C15:0) decreased with an increase in the growth temperature, whereas, palmitic acid (C16:0), stearic acid (C18:0) and DPA (C22:5n6) increased with an increase in the growth temperature. The composition of the major lipid class (%w/w) was slightly affected by the growth temperature. The fluidity of the organelle membrane or intracellular lipid (by DPH measurement) decreased with an increase in the growth temperatures, while the plasma membrane fluidity (by TMA-DPH measurement) could still maintain its fluidity in a wide range of temperatures (15 - 37°C). Furthermore, the distribution of DHA was found to be higher (36 - 54%) in phospholipid (PL) as compared to neutral lipid (NL) (20 - 41%).

Changes of erythrocyte deformability in rats acclimatized to hypoxia and its molemechanism / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To observe the changes of erythrocyte deformability in rats acclimatized to hypoxia and its molemechanism.</p><p><b>METHODS</b>Male rats were randomly divided into three groups (n = 10): normal control group, acute hypoxia group and hypoxia acclimatization group. Animals were exposed to hypoxia for 0, 1, 28 d, blooded from their hearts after anaesthetized, respectively. Erythrocyte deformability, membrane fluidity, cholesterin and total lipid, lipid components of erythrocyte membrane, erythrocyte membrane ATPase and the concentrations of Na+ and Ca2+ were measured respectively. The two-dimensional electrophoresis maps of the rats erythrocyte membrane protein were achieved. The different protein spots were founded by image master 2D elite and identified by mass spectrum.</p><p><b>RESULTS</b>(1) In acute hypoxia group, the deformability, membrane fluidity, the content of membrane cholesterin and total lipid were declined. The content of phosphatidylserines (PS), sphingomyelin (SM) in erythrocyte membrane lipids were increased, phosphatidylcholine (PC) reduced. The activity of ATP enzymes reduced and the concentration of Na+ and Ca2+ in erythrocyte increased. The two-dimensional electrophoresis maps of the rats erythrocyte membrane protein were achieved. Four of the seven protein spots selected increased and three of them showed no change. (2) In hypoxia acclimatization group, the deformability, membrane fluidity, the content of membrane cholesterin and total lipid were increased than those in acute hypoxia group, similar to normal group. The content of PS, SM in erythrocyte membrane lipids were reduced, PC increased. The activity of ATP enzymes induced and the concentration of Na+ and Ca2+ in erythrocyte increased after hypoxia acclimatization. Four of those protein spots mentioned increase and three declined after hypoxia acclimatization. They were respectively proved by mass spectrum to be alexin binding protein, aquaporin chip, membrane inhibitor reactive lysis, phospholipids scramblase, glucose transferase, aminophospholipid translocases, ATP-dependent floppase, the latter three proteins were associate with the overturning of erythrocyte membrane lipids.</p><p><b>CONCLUSION</b>Acute hypoxia caused the corresponding damage of erythrocyte deformability, erythrocyte membrane fluidity, erythrocyte membrane proteins erythrocyte expression, the activity of membrane ATPase and the concentration of Na+ and Ca2+ in erythrocyte. The parameters above were improved after hypoxia acclimatization, so hypoxia acclimatization effected positively in the damage to erythrocyte due to acute hypoxia. The three membrane proteins might play important roles in the deformability improved by hypoxia acclimatization, which included phospholipids scramblase, aminophospholipid translocases and ATP-dependent floppase.</p>

Effects of glucose concentration fluctuation on function of cultured bovine arterial endothelial cells / 中华心血管病杂志

<p><b>OBJECTIVE</b>To explore the effects of glucose concentration fluctuation on function of cultured bovine arterial endothelial cells and underlying mechanism.</p><p><b>METHODS</b>The thoracic aorta of newborn calf was used for primary endothelial cells culture. Cells were divided into 3 groups and cultured for 48 h: control group (C, 5.5 mmol/L), constant high glucose group (HG, 30 mmol/L) and glucose fluctuation (GF, three circles of 2 h 30 mmol/L followed by 3 h 5.5 mmol/L, 30 mmol/L overnight, repeat the whole procedure on the following day) groups. The membranes fluidity of endothelial cells was detected by fluorescence polarization method. The contents of sorbierite, aldose reductase (AR), sorbitol dehydrogenase (SDH) and advanced glycation end products (AGEs) were measured. RAGE, eNOS and ET-1 mRNA expressions were detected by semi-quantitative RT-PCR.</p><p><b>RESULTS</b>The membranes fluidity of endothelial cells in HG or GF group were significantly decreased compared with the control group (all P < 0.01) and significantly lower in GF group than those in HG group (all P < 0.01). Sorbierite, AR and AGEs concentrations were significantly higher in HG and GF groups than those in control group (all P < 0.01) and AR and AGEs concentrations were significantly higher in GF group than that in HG group (all P < 0.01). SDH of endothelial cells in HG or GF group were decreased compared with the control group and lower in GF group than in HG group (all P < 0.05). In addition, the mRNA levels of RAGE, eNOS and ET-1 were significantly upregulated compared with the control group (all P < 0.01).</p><p><b>CONCLUSIONS</b>Glucose concentration fluctuation can result in more severe bovine arterial endothelial cells dysfunction than high glucose via activating polyols metabolic pathways, upregulating the expression of AGEs, eNOS and ET-1. Therefore, glucose concentration fluctuation might play a crucial role on macrovascular complications of diabetes.</p>

Influencing factors of sperm membrane fluidity / 中华男科学杂志

Sperm membrane fluidity is one of the causes of male infertility, and it is thought to be related with temperature, reactive oxygen species, oxygen free radicals, anti-sperm antibodies, stilbestrol, and fenvalerate. A deeper insight into the influencing factors of sperm membrane fluidity is of vital importance for in vitro sperm preservation, revival of frozen-thawed sperm, in vitro fertilization and management of male infertility.

Multiglycosides of Tripterygium wilfordii increase sperm apoptosis in male rats / 中华男科学杂志

<p><b>OBJECTIVE</b>To study the effect of multiglycosides of Tripterygium wilfordii (GTW) on sperm apoptosis in male rats and its possible mechanisms.</p><p><b>METHODS</b>Sixteen male SD rats were equally assigned to two groups to receive GTW and carboxymethylcellulose (CMC) intragastrically, both at 20 mg/(kg x d) for 6 weeks. Then the epididymal sperm was collected for the measurement of the apoptosis rate, sperm membrane lipid fluidity and the contents of NO, MDA and SOD by flow cytometry and spectrophotometric determination.</p><p><b>RESULTS</b>After 6 weeks of medication, the GTW group showed a significant increase in sperm apoptosis and contents of NO and MDA (P < 0.01) and a remarkable decrease in sperm membrane lipid fluidity (P < 0.05) and SOD content (P < 0.01) as compared with the CMC control group.</p><p><b>CONCLUSION</b>GTW can damage sperm membrane lipid peroxidation and sperm membrane structure, increase sperm apoptosis, and reduce sperm membrane lipid fluidity.</p>

Ultrasound-mediated microbubble cavitation enhances gene transduction in rat pulmonary endothelial cells partially by affecting membrane fluidity and cytoskeleton structure / 南方医科大学学报

<p><b>OBJECTIVE</b>To evaluate the effect of therapeutic ultrasound-induced microbubble's cavitation on plasmid gene transduction in rat pulmonary endothelial cells in relation to the changes of membrane fluidity and cytoskeleton structure.</p><p><b>METHODS</b>Rat endothelial cells cultured in vitro were transfected with EGFP plasmid in the presence of protein microbubbles. During the transfection process, the cells were exposed to continuous 2 MHz ultrasonic irradiation for 30, 60, 90, 120 and 180 s (groups A, B, C, D and E, respectively) with the constant mechanical index (MI) of 1.0, or for 60 s with different mechanical index (MI) of 0.5, 0.75, 1.0, 1.5, and 1.8 (groups B1, B2, B3, B4 and B5, respectively). The changes of endothelial cytoskeletal structure and membrane fluidity were evaluated by immunofluorescence staining after the exposure.</p><p><b>RESULTS</b>EGFP gene transduction increase obviously with prolonged echo irradiation and increased MI. The intensity of immunofluorescence staining, which represented endothelial membrane fluidity, was 0.173±0.013, 0.250±0.037, 0.364±0.022, 0.381±0.019, and 0.395±0.009 in groups A-E, as compared with 0.171±0.017, 0.255±0.026, 0.378±0.007, 0.382±0.009 and 0.397±0.008 in groups B1-B5, respectively. The recovery intensity of the immunofluorescence staining representing the changes in microtubulin of the cytoskeleton structure was 159.15±4.79, 188.23±6.20, 205.80±4.48, 208.99±8.34, and 213.70±5.09 in groups A-E, and was 176.84±3.10, 187.57±14.52, 206.41±11.66, 220.12±13.39 and 221.16±12.78 in groups B1-B5, respectively. The endothelial membrane fluidity and microtubule fluorescence recovery intensity increased remarkably compared with the baseline (P<0.01) within the MI range of 0.50-1.0 and the exposure time of 30-90 s, but underwent no further changes in response to prolonged exposure time (180 s) at the MI of 1.5 (P>0.05). No changes in microfilament fluorescence intensity were observed after exposure to different MI or irradiation time.</p><p><b>CONCLUSION</b>Therapeutic ultrasound-mediated albumin microbubble cavitation allows enhances plasmid gene transduction without causing cytoskeleton damages. Increased endothelial membrane fluidity and changes in cytoskeleton structure, especially microtubulin, partially contribute to this enhancement.</p>

Recent advance in the mechanism study of polymeric inhibitors of P-glycoprotein / 药学学报

P-glycoprotein (P-gp) is an ATP-dependent multidrug efflux pump that acts as a major obstacle for oral drug delivery and cancer therapy. Recent reports have provided evidence that excipients often used in pharmaceutical formulations, such as Pluronic and TPGS, also have inhibitory effects on P-glycoprotein. Because inhibition of efflux transporters by polymeric inhibitors may dramatically increase the bioavailability of P-gp substrates with negligible side effects, identification of the mechanism and their structure activity relationship is therefore of significant importance for pharmaceutical development. Other than competitive inhibition for traditional inhibitors, polymeric inhibitors may modify P-gp function through alterations on membrane fluidity, inhibition of P-gp ATPase, depletion of intracellular ATP and down-regulating of P-gp expression. In the present review, the inhibition mechanism of potential polymeric inhibitors and their structure activity relationship will be discussed along with a brief introduction to the established methodologies.

The cytology mechanism of anti-parainfluenza virus infection of total flavone of Scutellaria barbata / 药学学报

In order to research into the cytology mechanism of anti-virus action of total flavone of Scutellaria barbata (TFSB), the effects of TFSB on host cells membrane potential, Na(+)-K(+)-ATPase activity and membrane fluidity after parainfluenza virus type1 (PIV-1) infection were studied. The changes of membrane potential which was fluorescent labeled with DiBAC4(3) and its changes were measured by flow cytometer. Phosphorus determination method and spectrophotometry were used to measure the Na(+)-K(+)-ATPase activity of Hep-2 cells membrane after PIV-1 infection. Hep-2 cells membrane phospholipids were fluorescent labeled with NBD-C6-HPC and membrane fluidity was measured by confocal scanning laser microscope. The result demonstrated that post PIV-1 infection membrane potential decreased significantly and the membrane was in a state of hyperpolarization, Na(+)-K(+)-ATPase activity increased significantly and membrane fluidity decreased significantly. There was no apparent interfere effect of TFSB on the changes of membrane potential and Na(+)-K(+)-ATPase activity after PIV-1 infection, while membrane fluidity improved significantly. It was indicated that the cytology mechanism of PIV-1 infection might be related to membrane hyperpolarization, Na(+)-K(+)-ATPase activity increase and membrane fluidity decrease. TFSB can improve membrane fluidity and prevent the infection by protecting the cell membrane. But it is possible that the anti-PIV-1 mechanisms of TFSB had nothing to do with membrane potential and Na(+)-K(+)-ATPase activity.

Protective effect of Pogostemon cablin on membrane fluidity of intestinal epithelia cell in ischemia/ reperfusion rats after ischemia/reperfusion / 中国中西医结合杂志

<p><b>OBJECTIVE</b>To observe the effects of Pogostemon cablin (Blanco) Benth. (PCB), a Chinese aromatic herbal medicine, on serum levels of nitric oxide (NO), tumor necrosis factor-alpha (TNF-alpha), and membrane fluidity of intestinal epithelial cells (IMC) in rats undergoing lower limbs ischemic reperfusion (I/R), for exploring its action in protecting intestinal barrier and the possible mechanisms, and to seek a new way, viewing from Chinese medicine, for providing the experimental bases of gastrointestinal protection against trauma or surgical operation.</p><p><b>METHODS</b>Eighty adult Wistar rats were induced into lower limb I/R model and randomized equally into the model group, the three PCB water extract groups treated respectively with high- (4 g x kg(-1) x d(-10), middle- (3 g x kg(-1) x d(-1)), and low-dose (2 g x kg(-1) x d(-1)) of PCB water extract, and three PCB volatile oil groups treated respectively with high- (4 g x kg(-1) x d(-1)), middle- (3 g x kg(-1) x d(-1)), low-dose (2 g x kg(-1) d(-1) of PCB volatile oil. Besides, 10 healthy rats was allocated in a normal control group. PCB preparation was given via gastric infusion for 5 successive days just before modeling. The serum levels of NO and TNF-alpha were monitored, and the membranous fluidity of IMC at I/R region was determined by fluorescence polarization technique.</p><p><b>RESULTS</b>Compared with the control group, both serum NO and TNF-alpha levels in model rats were significantly higher (P < 0.01), and the fluorescence polarization value (P) of IMC obviously increased at the same time (P < 0.05). As compared with the model group, the serum level of NO and TNF-alpha significantly reduced in all the PCB treated groups (P < 0.01 or P < 0.05). As for the membrane fluidity, significant difference was shown between the model group with low-dose of PCB water extract and middle-dose of PCB volatile oil (P < 0.05).</p><p><b>CONCLUSION</b>PCB could effectively protect the intestinal barrier function by way of maintaining the membrane fluidity of IMC through regulating the level of NO and TNF-alpha in serum.</p>

H2O2 induces changes in the plasma membrane of Saccharomyces cerevisiae / 生物工程学报

This article reviews the recent studies on H2O2 adaptation of Saccharomyces cerevisiae. When the cell exposed in the H2O2 sub-lethal doses, the plasma membrane permeability decreased, meanwhile the plasma membrane fluidity is minished. These changes resulted in a gradient across the plasma membrane, which conferring a higher resistance to oxidative stress. Recent work has also shown that the yeast cells adapted to H2O2 would lead to several changes in the expression of genes coding the key enzymes involved in the biosynthesis of lipid profile and in the organization of lipid microdomains of the plasma membrane, which finally decreased its' permeability and fluidity. The reorganization of the plasma membrane might be the major mechanism of the H2O2 adaptation. Once the yeast cells adapted to the external H2O2, changes in plasma occurred. The H2O2 dependent signaling pathways in the plasma membrane might be activated by high levels of H2O2. But the details of the signaling events should still be further studies.

Substituted phenols as pollutants that affect membrane fluidity.

In a toxicological context, the cellular effects of a variety of molecular compounds interacting with membranes may be understood in terms of their ability to affect and modulate lipid-membrane physical properties and even slight changes in membrane fluidity may cause aberrant function and pathological processes. Different model systems (mice splenocytes and liposomes) have been used in modelling studies of the physical effects on lipid bilayers underlying the action of membrane active phenolic compounds, considered by EPA (Environmental Protection Agency) as priority pollutants (phenol; 2-chlorophenol; 2,4-dichlorophenol; 2,4,6-trichlorophenol; pentachlorophenol; 2-nitrophenol; 2,4-dinitrophenol; 2-methyl-4,6-dinitrophenol). Membrane fluidity was assessed by fluorescence steady-state anisotropy of a fluorescent probe 1,6-diphenil-1,3,5-hexatriene (DPH). The substituted phenols increased the fluidity of cells and liposome membranes in a concentration dependent manner and the nitro substituted phenols were the most efficient perturbing the biophysical properties of the membrane. A good parallelism has been established between the results obtained with cell models and artificial liposome model systems, implying that liposomes are useful alternative systems in membrane modification studies and can be conveniently used in order to evaluate the potential toxic effect of phenol derivatives that are common environmental pollutants.

Membrane fluidity and lipid composition of fluconazole resistant and susceptible strains of Candida albicans isolated from diabetic patients / Fluidez e composição lipídica da membrana de cepas de Candida albicans resistentes e sensíveis ao fluconazol, isoladas de pacientes diabéticos

Ten clinical isolates of Candida albicans, five strains belonging to each of fluconazole resistant and susceptible groups isolated from diabetic patients, were studied for the membrane fluidity and lipid composition. Compared to fluconazole susceptible strains, fluconazole resistant ones exhibited enhanced membrane fluidity as measured by fluorescence polarization technique. The increased membrane fluidity was reflected in the decreased p-values exhibited by the resistant strains. On the other hand, susceptible isolates contained higher amount of ergosterol, almost twice as compared to resistant isolates which might have contributed to their lower membrane fluidity. However, no significant alteration was observed in the phospholipid and fatty acid composition of these isolates. Labeling experiments with fluorescamine dye revealed that the percentage of the exposed aminophospholipid, phosphatidylethanolamine was highest in the resistant strains as compared to the susceptible strains, indicating a possible overexpression of CDR1 and CDR2 genes in resistant strains. The results presented here suggest that the changes in the ergosterol content and overexpression of ABC transporter genes CDR1 and CDR2 could contributeto fluconazole resistance in C. albicans isolated from diabetic patients.

Dez isolados clínicos, sendo cinco resistentes e cinco sensíveis ao fluconazol, obtidos de pacientes diabéticos, foram estudados quanto à fluidez e composição química da membrana. Quando comparados aos isolados sensíveis ao fluconazol, os isolados resistentes apresentaram fluidez de membrana aumentada, conforme mensurado pela técnica de polarização fluorescente. A fluidez de membrana aumentada refletiu-se pelos valores mais baixos de p. Por outro lado, os isolados sensíveis continham quantidades mais elevadas de ergosterol, quase o dobro dos isolados resistentes, o que pode ter contribuído para a fluidez de membrana mais baixa. Entretanto, não se observou alteração significativa na composição fosfolipídica e de ácidos graxos nesses isolados. Experimentos de marcação com corante fluorescamina indicaram que a porcentagem de aminofosfolípides e fosfatidiletanolamina expostos foi mais elevada nos isolados resistentes do que nos sensíveis, indicando uma possível superexpressão dos genes CDR1 e CDR2 nos isolados resistentes. Os resultados aqui apresentados sugerem que alterações no teor de ergosterol e superexpressão dos genes ABC transportadores CDR1 e CDR2 podem contribuir na resistência ao fluconazol em isolados de C. albicans de pacientes diabéticos.