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Biol. Res ; 48: 1-6, 2015. graf
Article in English | LILACS | ID: biblio-950781


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.

Animals , Male , Rats , Mitochondria, Liver/drug effects , Adenosine Triphosphatases/metabolism , Karwinskia/toxicity , Membrane Fluidity/drug effects , Subcellular Fractions/drug effects , Submitochondrial Particles/drug effects , Mitochondria, Liver/enzymology , Random Allocation , Rats, Sprague-Dawley , Proton-Motive Force/drug effects , Fruit/toxicity
Braz. j. med. biol. res ; 45(6): 473-481, June 2012. ilus, tab
Article in English | LILACS | ID: lil-622783


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.

Humans , Antioxidants/pharmacology , Erythrocyte Membrane/drug effects , Hydrogen Peroxide/pharmacology , Lipid Peroxidation/drug effects , Membrane Proteins/metabolism , Thiobarbituric Acid Reactive Substances/metabolism , Ascorbic Acid/pharmacology , Catechin/pharmacology , Cyclic N-Oxides/metabolism , Electron Spin Resonance Spectroscopy , Erythrocyte Membrane/chemistry , Erythrocyte Membrane/physiology , Hemolysis , Hydrogen-Ion Concentration , Hemoglobins/metabolism , Hydrogen Peroxide/metabolism , Membrane Fluidity/drug effects , Oxidative Stress/physiology , alpha-Tocopherol/pharmacology
J Environ Biol ; 2008 Sep; 29(5): 733-8
Article in English | IMSEAR | ID: sea-113601


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.

Animals , Cells, Cultured , Environmental Pollutants/toxicity , Fluorescence Polarization , Liposomes , Membrane Fluidity/drug effects , Mice , Phenols/toxicity
Indian J Biochem Biophys ; 2001 Dec; 38(6): 412-6
Article in English | IMSEAR | ID: sea-28496


The liquid membrane phenomenon in angiotensin converting enzyme (ACE) inhibitors namely, captopril and lisinopril has been studied. Hydraulic permeability data have been obtained to demonstrate the existence of the liquid membrane in series with a supporting membrane generated by the ACE inhibitors. Data on the transport of the relevant permeants in presence of the liquid membrane formed by ACE inhibitors indicate that liquid membrane phenomenon is likely to play a significant role in the action of ACE inhibitors.

Angiotensin-Converting Enzyme Inhibitors/pharmacology , Captopril/pharmacology , Cellulose/analogs & derivatives , Lisinopril/pharmacology , Membrane Fluidity/drug effects , Membranes, Artificial , Permeability , Surface Properties
Indian J Physiol Pharmacol ; 2001 Oct; 45(4): 421-7
Article in English | IMSEAR | ID: sea-108398


Effects of exposure of an alcoholic beverage (arrack and its equivalent quantity of alcohol throughout pregnancy and lactation on brain lipids were investigated. Female rats were exposed to arrack (12.00 ml/kg body weigh/day) and ethanol (4.00 g/kg body weight day) before conception and throughout gestation and lactation. For 21 days pups were nursed by their own mothers, afterwards they were fed normal laboratory feed. We found that the level of cholesterol, phospholipids, triacylglycerols, free fatty acids, cerebrosides, ceramide dihexosides, ceramide polyhexosides, sulfatids,, mono and diglycosyl diglycerides and gangliosides were increased in the brain of 21st and 45th day pups. The alterations in the glycolipid profile of the brain persisted even when pups were not directly exposed to alcohol. These alterations in the glycolipid and ganglioside metabolism may be associated with the developmental abnormalities of the brain seen in FAS. The elevation produced in the glycolipid profile of arrack administered pups were more than that caused by its equivalent quantity of ethanol. This suggested an interaction of congeners in the arrack with the alcohol.

Animals , Brain Chemistry/drug effects , Ethanol/toxicity , Female , Fetus/drug effects , Gangliosides/analysis , Glycolipids/analysis , Lactation , Lipids/analysis , Membrane Fluidity/drug effects , Pregnancy , Rats , Rats, Sprague-Dawley
Indian J Physiol Pharmacol ; 1992 Oct; 36(4): 276-8
Article in English | IMSEAR | ID: sea-106641


The effect of Amiodarone (AD), a cationic amphiphilic drug, on erythrocytes and leucocytes was studied. Treatment of rats with AD showed a significant decrease in the red cell count and the level of Hemoglobin. Amiodarone altered the fluidity of the erythrocyte membrane followed by a decrease in the activities of membrane bound enzymes like (Na+, K+)-ATPase, Acetylcholine esterase and NADH dehydrogenase. A slight increase in the leucocyte count was also observed in the treated animals.

Amiodarone/pharmacology , Animals , Cholesterol/metabolism , Erythrocyte Count/drug effects , Erythrocyte Membrane/drug effects , Hemoglobins/metabolism , Leukocyte Count/drug effects , Male , Membrane Fluidity/drug effects , Phospholipids/metabolism , Rats , Rats, Wistar , Sodium-Potassium-Exchanging ATPase/blood