The aim of this study was to provide a basis for studying the molecular mechanism of pharmacological action of chlorhexidine digluconate. Fluorescence polarization of n- (9-anthroyloxy) stearic acid was used to examine the effect of chlorhexidine digluconate on differential rotational mobility of different positions of the number of membrane bilayer phospholipid carbon atoms. The six membrane components differed with respect to 2, 3, 6, 9, 12, and 16- (9-anthroyloxy) stearic acid (2-AS, 3-AS, 6-AS, 9-AS, 12-AS and 16-AP) probes, indicating different membrane fluidity. Chlorhexidine digluconate increased the rate of rotational mobility of hydrocarbon interior of the cultured Porphyromonas gingivalis outer membranes (OPG) in a dose-dependent manner, but decreased the mobility of surface region (membrane interface) of the OPG. Disordering or ordering effects of chlorhexidine digluconate on membrane lipids may be responsible for some, but not all of its bacteriostatic and bactericidal actions.
Carbon ; Chlorhexidine* ; Fluorescence Polarization ; Membrane Fluidity ; Membrane Lipids ; Membranes* ; Porphyromonas gingivalis ; Porphyromonas* ; Thiram

Direct exposure of renal tubular brush-border membranes (BBM) to free cadmium (Cd) causes a reduction in phosphate (Pi) transport capacity. Biochemical mechanism of this reduction was investigated in the present study. Renal proximal tubular brush-border membrane vesicles (BBMV) were isolated from rabbit kidney outer cortex by Mg precipitation method. Vesicles were exposed to 50~200 muM CdCl2 for 30 min, then the phosphate transporter activity was determined. The range of Cd concentration employed in this study was comparable to that of the unbound Cd documented in renal cortical tissues of Cd-exposed animals at the time of onset of renal dysfunction. The rate of sodium-dependent phosphate transport (Na+-Pi cotransport) by BBMV was determined by 32P-labeled inorganic phosphate uptake, and the number of Na+/-Pi cotransporters in the BBM was assessed by Pi-protectable 14C-labeled phosphonoformic acid ((14C)PFA) binding. The exposure of BBMV to Cd decreased the Na+-Pi cotransport activity in proportion to the Cd concentration in the preincubation medium, but it showed no apparent effect on the Pi-protectable PFA binding. These results indicate that an interaction of renal BBM with free Cd induces a reduction in Na+-Pi cotransport activity without altering the carrier density in the membrane. This, in turn, suggest that the suppression of phosphate transport capacity (Vmax) observed in Cd-treated renal BBM is due to a reduction in Na+-Pi translocation by existing carriers, possibly by Cd-induced fall in membrane fluidity.
Animals ; Cadmium ; Cadmium Chloride ; Foscarnet* ; Kidney ; Membrane Fluidity ; Membranes* ; Phosphate Transport Proteins*

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.
Humans ; Infertility, Male ; Male ; Membrane Fluidity ; Semen Preservation ; Sperm Motility ; Sperm-Ovum Interactions ; Spermatozoa ; physiology

Real-time quantitative PCR was used to characterize HearNPV DNA replication in exponential and stationary phases of HzAM1 cells. Results showed that the doubling time of HzAM1 cells was 22 h in exponential phases. Most of the exponential cells were in S phase (48.6%), and most of the stationary cells in G2/M phase (72.6%). The replication of viral DNA was completed within 60 h post infection (h p. i.) in different phases of HzAM1 cells. During 14 to 20 h p. i., the doubling time of HearNPV replica-tion was 1.8 h in exponential cells and 1.9 h in stationary cells, and no significant difference was found between them. But the amounts of BV entering and releasing, the final progeny virions and viral protein products in the infected exponential phase cells were obviously higher than that in the stationary phase cells. 25% of the total synthesized viral DNAs were released from infected exponential phase cells, but on-ly 13% from the infected stationary phase cells. Viral DNA started to be replicated from 7-8 h p. i. both in infected exponential phase and in stationary phase cells. But in infected exponential phase cells, BVs were started to release from 18-20 h p. i., and BVs were started to release from 22-25 h p. i. from infected sta-tionary phase cells. During 30-60 h p. i., the BV releasing rate was about 483 copies/cell/h in the expo-nential phase cells, but was 100 copies/cell/h in the stationary-phase cells. The initial viral DNA entering into exponential phase cells was much more than that entered into the stationary phase cells. The data of cell membrane fluidity at exponential and stationary phases suggested that the fluidity of cell membrane played an important role during virus entry.
Animals ; Cell Cycle ; Cell Line ; DNA Replication ; Membrane Fluidity ; Moths ; Nucleopolyhedrovirus ; physiology ; Virus Internalization ; Virus Replication

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.
Alanine Transaminase ; Aspartate Aminotransferases ; Bilirubin ; Diet ; Erythrocyte Indices ; Erythrocyte Membrane ; Erythrocytes ; Glutathione Peroxidase ; Malondialdehyde ; Membrane Fluidity ; Phosphorus* ; Superoxide Dismutase

To elucidate the molecular mechanism of pharmacological action of local anesthetics, we studied membrane actions of tetracaine, bupivacaine, lidocaine, prilocaine and procaine. Fluorescence polarization of n- (9-anthroyloxy) stearic acid (n-AS) was used to examine the effects of these local anesthetics on differential rotational mobility of different positions of the number of synaptosomal plasma membrane vesicle (SPMV) phospholipid carbon atoms. The four membrane components differed with respect to 3, 6, 9 and 16- (9-anthroyloxy) stearic acid (3-AS, 6-AS, 9-AS and 16-AP) probes, indicating that differences in the membrane fluidity might be present. Degrees of the rotational mobility of 3-AS, 6-AS, 9-AS and 16-AP were different depending on depth of hydrocarbon interior. In a dose-dependent manner, tetracaine, bupivacaine, lidocaine, prilocaine and procaine decreased anisotropy of 3-AS, 6-AS, 9-AS and 16-AP in the hydrocarbon interior of the SPMV. These results indicate that local anesthetics have significant disordering effects on hydrocarbon interior of the SPMV, thus affecting the transport of Na+ and K+ in nerve membranes and leading to anesthetic action.
Anesthetics, Local* ; Anisotropy ; Bupivacaine ; Carbon ; Cell Membrane ; Fluorescence Polarization ; Lidocaine ; Membrane Fluidity ; Membranes* ; Neurons* ; Prilocaine ; Procaine ; Tetracaine

OBJECTIVETo 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.

METHODSRat 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.

RESULTSEGFP 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.

CONCLUSIONTherapeutic 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.

Animals ; Cells, Cultured ; Cytoskeleton ; Endothelial Cells ; Lung ; cytology ; Membrane Fluidity ; Microbubbles ; Plasmids ; Rats ; Rats, Sprague-Dawley ; Sonication ; Transfection

OBJECTIVETo study the effects of domoic acid (DA) on membrane function of primary cultured rat glial cell.

METHODSAfter the glial cells were treated with 6.4 x 10(-2), 6.4 x 10(-3) and 6.4 x 10(-4) micromol/L DA for 24 h, the activities of Na(+)-K(+)-ATPase and Ca(2+)-Mg(2+)-ATPase, the membrane fluidity and the permeability were measured to reflect the membrane function.

RESULTSAfter treatment of DA for 24 h, the activities of Na(+)-K(+)-ATPase and Ca(2+)-Mg(2+)-ATPase were inhibited significantly, the membrane fluidity decreased and the membrane permeability increased. The fluorescence polarization and microviscosity in the low, middle and high dosage treatment groups were 0.0626 +/- 0.0051, 0.0685 +/- 0.0097, 0.0648 +/- 0.0086 and 0.3154 +/- 0.0298, 0.3510 +/- 0.0571, 0.3286 +/- 0.0504 respectively, compared with the control group (0.0481 +/- 0.0069 and 0.2338 +/- 0.0372) (P < 0.01).

CONCLUSIONDA has obvious effects on membrane function of rat glial cells and may cause further injury on the cells.

Animals ; Cell Membrane ; drug effects ; Cell Membrane Permeability ; drug effects ; Cells, Cultured ; Kainic Acid ; analogs & derivatives ; pharmacology ; Membrane Fluidity ; drug effects ; Neuroglia ; drug effects ; Rats ; Rats, Sprague-Dawley

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.
Cell Membrane ; drug effects ; metabolism ; Cell Membrane Permeability ; drug effects ; Hydrogen Peroxide ; pharmacology ; Membrane Fluidity ; drug effects ; Saccharomyces cerevisiae ; cytology ; drug effects ; Signal Transduction ; drug effects

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.
Caco-2 Cells ; Cations ; Cell Membrane ; drug effects ; Cell Membrane Permeability ; drug effects ; Humans ; Insulin ; metabolism ; Membrane Fluidity ; drug effects ; Microscopy, Atomic Force ; Peptides, Cyclic ; pharmacology