RESUMEN
BACKGROUND: Ecteinascidin 743 (Et 743), a natural product derived from a marine tunicate, is a potent antitumor agent presently in phase II clinical trials. Et 743 binds in the minor groove of DNA and alkylates N2 of guanine via a unique mechanism involving catalytic activation. The sequence selectivity of Et 743 is governed by different patterns of hydrogen-bonding to DNA, which results in differential reversibility of the covalent adducts. As determined by nuclear magnetic resonance spectroscopy, the preferred sequences 5'-PuGC and 5'-PyGG are stabilized by a hydrogen-bonding network, while the non-preferred sequences 5'-NG(A/T) are much less stabilized due to the lack of a key hydrogen bond to the GC base pair on the 3'-side of the alkylated guanine. RESULTS: Mammalian cell lines (XPB, XPD, XPF, XPG, and ERCC1) deficient in the nucleotide excision repair (NER) gene products show resistance to Et 743. The recognition and subsequent incision of Et 743-DNA adducts by the bacterial multisubunit endonuclease UvrABC were used to evaluate DNA repair-mediated toxicity as a rationale for the resistance of NER-defective cell lines and the antitumor activity of Et 743. The Et 743-DNA adducts are indeed recognized and incised by the UvrABC repair proteins; however, the pattern of incision indicated that the non-preferred, and less stable, sequences (i.e. 5'-NG(A/T)) modified with Et 743 are generally incised at a much higher efficiency than the preferred, more stable sequences (i.e. 5'-PuGC or 5'-PyGG). In addition, within the same Et 743 recognition sequence, the level of incision varies, indicating that flanking regions also contribute to the differential incision frequency. CONCLUSIONS: The inefficient repair incision by the UvrABC nuclease of Et 743-DNA adducts provides a basis for rationalizing the observed repair-dependent cytotoxicities of these DNA adducts, if other associated structural properties of Et 743-DNA adducts are taken into account. In particular, the wedge-shaped Et 743, which forces open the minor groove of DNA, introducing a major groove bend, and the extrahelical protrusion of the C-subunit of Et 743 provide unique characteristics alongside the hydrogen-bonding stabilization of a covalent DNA adduct, which we propose traps an intermediate in NER processing of Et 743-DNA adducts. This trapped intermediate protein-Et 743-DNA adduct complex can be considered analogous to a poisoned topoisomerase I- or topoisomerase II-DNA complex. In the absence of an intact NER nuclease complex, this toxic lesion is unable to form, and the Et 743-DNA adducts, although not repaired by the NER pathway, are less toxic to cells. Conversely, elevated levels of either of these nucleases should lead to enhanced Et 743 toxicity.
Asunto(s)
Antineoplásicos Alquilantes/química , Antineoplásicos Alquilantes/metabolismo , ADN/metabolismo , Dioxoles/química , Sistemas de Liberación de Medicamentos , Endodesoxirribonucleasas/metabolismo , Proteínas de Escherichia coli/metabolismo , Isoquinolinas/química , Animales , Antineoplásicos Alquilantes/farmacología , Secuencia de Bases , Sitios de Unión , Células CHO , Supervivencia Celular/efectos de los fármacos , Cricetinae , ADN/química , ADN/genética , Aductos de ADN/química , Aductos de ADN/metabolismo , Reparación del ADN , Dioxoles/metabolismo , Dioxoles/farmacología , Marcación de Gen/métodos , Humanos , Isoquinolinas/metabolismo , Isoquinolinas/farmacología , Modelos Moleculares , Datos de Secuencia Molecular , Mutagénesis Insercional/métodos , Tetrahidroisoquinolinas , TrabectedinaRESUMEN
Dimeric DNA cross-linking compounds have emerged as important new antitumor agents. We report the synthesis and biochemical evaluation of a select set of dimeric mitomycins in which the two mitomycin units are tethered at either the mitomycin C(7) amino or the aziridine N(1a) positions. Significantly, mitomycin C (1) itself is the prototypical bioreductive DNA cross-linking agent. DNA cross-linking experiments using a denaturing-gel-electrophoresis-based assay showed that the extent of DNA cross-linking for select dimeric mitomycins can exceed that of the parent compound, mitomycin C, and that the reaction proceeds, in part, at the two distal C(1) sites in the mitomycins. The efficiency of DNA cross-linking depended on the nature of the linker and the position of linker unit's attachment. When we compared the efficiency of DNA cross-linking for the dimeric mitomycins with their in vitro cytotoxicities in cultured human tumor cells, we observed a poor correlation. The mitomycins that gave the highest levels of DNA cross-linked adducts displayed the weakest cytotoxicities. These findings determined that the denaturing-gel-electrophoresis-based assay was a poor predictor of cytotoxic activity.
Asunto(s)
Antibióticos Antineoplásicos/síntesis química , Reactivos de Enlaces Cruzados/síntesis química , ADN/química , Mitomicina/síntesis química , Antibióticos Antineoplásicos/química , Antibióticos Antineoplásicos/farmacología , Reactivos de Enlaces Cruzados/química , Reactivos de Enlaces Cruzados/farmacología , Dimerización , Ensayos de Selección de Medicamentos Antitumorales , Electroforesis en Gel de Agar , Humanos , Mitomicina/química , Mitomicina/farmacología , Relación Estructura-Actividad , Células Tumorales CultivadasRESUMEN
Recent studies have documented that cytosine C(5) methylation of CpG sequences enhances mitomycin C (1) adduction. The reports differ on the extent and uniformity of 1 modification at the nucleotide level. We have determined the bonding profiles for mitomycin monoalkylation in two DNA restriction fragments where the CpG sequences were methylated. Three mitomycin substrates were used and two different enzymatic assays employed to monitor the extent of drug modification at the individual base sites. Drug DNA modification was accomplished with I and 10-decarbamoylmitomycin C (2) under reductive (Na2S2O4) condilions and with N-methyl-7-methoxyaziridinomitosene (3) under nonreductive conditions. The UvrABC incision assay permitted us to quantitate the sites of drug adduction, and the lambda-exonuclease stop assay provided a qualitative estimation of drug-DNA modification consistent with the UvrABC data. We learned that C(5) cytosine methylation (m5C) enhanced the extent of overall DNA modification. Using the UvrABC endonuclease assay, we found that modification by 1 increased 2.0 and 7.4 times for the two DNA restriction fragments. Analysis of the modification sites at the nucleotide sequence level revealed that guanine (G) was the only base modified and that the overall increased level of DNA adduction was due to enhanced modification of select m5CpG* (G* = mitomycin (mitosene) adduction sites) loci compared with CpG* sites: the largest differences reached two orders of magnitude. Significantly, not all CpG* sites underwent increased drug adduction upon C(5) cytosine methylation. The effect of C(5) cytosine methylation on the drug adduction profiles was less pronounced for G* sites located within dinucleotide sequences other than CpG*. We observed that DNA methylation often led to slightly diminished adduction levels at these sites. The different m5CpG* adduction patterns provided distinctive sequence-selective bonding profiles for 1-3. We have attributed the large differences in guanine reactivity to DNA structural factors created, in part, by C(5) cytosine methylation. The significance of these findings in cancer chemotherapy is briefly discussed.
Asunto(s)
Citosina/química , ADN/química , Mitomicina/química , Autorradiografía , Secuencia de Bases , ADN/genética , ADN/metabolismo , Aductos de ADN/química , Densitometría , Desoxirribonucleasa EcoRI/química , Electroforesis en Gel de Poliacrilamida , Exonucleasas/química , Metilación , Mitomicina/metabolismo , Datos de Secuencia Molecular , Plásmidos/genética , Mapeo RestrictivoRESUMEN
We have established that UvrABC nuclease is equally efficient in cutting mitomycin C (MC)-DNA monoadducts formed at different sequences and that the degree of UvrABC cutting represents the extent of drug-DNA bonding. Using this method we determined the effect of C5 cytosine methylation on the DNA monoalkylation by MC and the related analogues N-methyl-7-methoxyaziridinomitosene (MS-NMA) and 10-decarbamoylmitomycin C (DC-MC). We have found that C5 cytosine methylation at CpG sites greatly enhances MC and MS-NMA DNA adduct formation at those sites while reducing adduct formation at non-CpG sequences. In contrast, although DC-MC DNA bonding at CpG sites is greatly enhanced by CpG methylation, its bonding at non-CpG sequences is not appreciably affected. These cumulative results suggest that C5 cytosine methylation at CpG sites enhances sequence selectivity of drug-DNA bonding. We propose that the methylation pattern and status (hypo- or hypermethylation) of genomic DNA may determine the cells' susceptibility to MC and its analogues, and these effects may, in turn, play a crucial role in the antitumor activities of the drugs.
Asunto(s)
Alquilantes/química , Islas de CpG , Citosina/química , Metilación de ADN , ADN/química , Proteínas de Escherichia coli , Mitomicina/química , Animales , Aziridinas/química , Aziridinas/metabolismo , Células CHO , Cricetinae , Citosina/metabolismo , ADN/metabolismo , Aductos de ADN/química , Aductos de ADN/metabolismo , Daño del ADN , Endodesoxirribonucleasas/química , Endodesoxirribonucleasas/metabolismo , Guanina/química , Guanina/metabolismo , Cinética , Mitomicinas/química , Mitomicinas/metabolismoRESUMEN
The effects of hepatotropic growth factors (HGFs) and phospholipid drugs on the recovery of functions and the regeneration of the rat liver were studied in CC14-induced toxic damage and after partial hepatectomy (PHE). HGFs isolated from the cytoplasmic cells of the regenerating liver, as well as from the liver of the animals given prodigiozan and from the media taken after culturing the explants of the regenerating liver were found to stimulate DNA synthesis and hepatocytic proliferation following PHE and in the cirrhotic liver. Prodigiozan was shown to induce the formation of HGFs not only in the rat liver following PHE, but in the liver of intact animals. It was established that the covalently binding complex of albumin and bilirubin stimulated the synthesis of proteins and DNA in the regenerating liver, but non-covalently binding complex inhibited these processes. When CC14 was administered to the animals, the two complexes enhanced the reparative synthesis of DNA, without changing the level of replicating synthesis, the non-covalently binding complex completely eliminating the single-strand breaks in DNA. Phospholipid agents containing soybean and sunflower phosphatidylcholines increased the synthesis of RNA and albumin, which were decreased due to exposure to CC14 and had the property of stimulating the synthesis of total DNA and considerably enhancing that of mitochondrial DNA.
Asunto(s)
Antibacterianos/farmacología , Enfermedad Hepática Inducida por Sustancias y Drogas/tratamiento farmacológico , Hepatectomía , Factor de Crecimiento de Hepatocito/farmacología , Regeneración Hepática/efectos de los fármacos , Hígado/efectos de los fármacos , Fosfatidilcolinas/farmacología , Prodigiozán/farmacología , Animales , Antibacterianos/uso terapéutico , Tetracloruro de Carbono/toxicidad , Enfermedad Hepática Inducida por Sustancias y Drogas/etiología , ADN/biosíntesis , Helianthus , Factor de Crecimiento de Hepatocito/uso terapéutico , Hígado/metabolismo , Hígado/fisiología , Cirrosis Hepática Experimental/cirugía , Fosfatidilcolinas/uso terapéutico , Prodigiozán/uso terapéutico , ARN/biosíntesis , Ratas , Glycine maxRESUMEN
Information of the specific structure of the activated mitomycin species leading to selective DNA bonding has been secured by determining the bonding sequence selectivities of modified mitomycins in which the identity, spatial orientation, and state of unsaturation of the C-9 and C-9a substituents in the mitomycin were varied. Both mitomycin-9a-sulfonate (8) and mitomycin D (9) gave DNA bonding profiles comparable to those obtained for mitomycin C (1) under reductive conditions, indicating that neither the stereochemistry of the C-9 and C-9a substituents nor the identity of the leaving group at C-9a influenced the site(s) of DNA bonding. These results indicated that aromatization of the dihydropyrrole ring in mitomycin C precedes DNA binding and mitomycin C-1 bonding.
Asunto(s)
ADN/metabolismo , Mitomicina/metabolismo , Secuencia de Bases , Sitios de Unión , ADN/química , Mitomicina/química , Datos de Secuencia Molecular , Estructura Molecular , Oxidación-Reducción , EstereoisomerismoRESUMEN
Noncovalently bound complexes of albumin and bilirubin were found to stimulate DNA and protein synthesis in partially hepatectomized regenerating rat liver tissue, while the covalently bound complex inhibited both these synthesis types in liver tissue after partial hepatectomy. Splenectomy of intact rats caused an induction of DNA and protein synthesis in liver tissue but partial hepatectomy decreased drastically the synthesis rate in spleen, thus suggesting that humoral factors stimulating the proliferation response in liver and spleen tissues were developed after spleen- and hepatectomies. The covalently bound albumin and bilirubin complex did not affect the rate of DNA and protein synthesis in liver tissue of splenectomized rats, while the complex with noncovalent bonds restored the rate of DNA and protein synthesis in the spleen of rats with partial hepatectomy. Only the noncovalently bound complex of albumin and bilirubin exhibited the properties inherent in hepatotropic growing factor whereas albumin administration was not effective. Possible structure and action of the noncovalently bound albumin and bilirubin complex are discussed.
Asunto(s)
Bilirrubina/farmacología , Replicación del ADN/efectos de los fármacos , Sustancias de Crecimiento/farmacología , Hígado/efectos de los fármacos , Biosíntesis de Proteínas , Albúmina Sérica/farmacología , Bazo/efectos de los fármacos , Animales , División Celular/efectos de los fármacos , Hepatectomía , Hígado/citología , Hígado/metabolismo , Masculino , Ratas , Albúmina Sérica Humana , Bazo/citología , Bazo/metabolismo , EsplenectomíaRESUMEN
The effects of non-covalently bound complexes of allogeneic or syngeneic albumin with bilirubin and of albumin alone on DNA and protein synthesis in rat liver and spleen cells after partial hepatectomy were studied. The assay procedure was based on different intravenous doses of these compounds in rats after partial hepatectomy. The allogeneic albumin-bilirubin complex (at protein doses of 0.9 and 90 micrograms/100 g body weight) stimulated DNA and protein synthesis in liver cells irrespective of the dose. At a dose of 0.9 micrograms the syngeneic albumin-bilirubin complex enhanced DNA synthesis insignificantly and produced no effect on protein synthesis, while at a dose of 90 micrograms, both DNA and protein synthesis were considerably increased. Allogeneic or syngeneic albumin at the above doses stimulated only protein, not DNA, synthesis in the liver, while the highest stimulation was at 90 micrograms allogeneic albumin. It was found also that partial hepatectomy decreased DNA and protein synthesis in spleen cells. Albumin-bilirubin complex with allogeneic or syngeneic albumin and albumin alone either significantly enhanced DNA and protein synthesis in the spleen, compared to controls, or only restored synthesis to control levels. Thus DNA and protein synthesis in the regenerating liver and spleen was significantly enhanced after the injection of small doses of the albumin-bilirubin complex, indicating the existence of small amounts of a similar endogenous complex in the blood stream.
Asunto(s)
Bilirrubina/farmacología , ADN/biosíntesis , Hepatectomía , Hígado/metabolismo , Biosíntesis de Proteínas , Albúmina Sérica/farmacología , Bazo/metabolismo , Animales , Bovinos/sangre , Sustancias de Crecimiento/farmacología , Hepatectomía/métodos , Hígado/efectos de los fármacos , Masculino , Ratas/sangre , Albúmina Sérica Humana , Bazo/efectos de los fármacosRESUMEN
Antioxidative activity of potassium- and sodium glycyrrhizins was detected by means of chemoluminescence procedure. As shown by the spectral studies the glycyrrhizin salts formed complex of the I type with cytochrome P-450 from rat liver microsomes, inhibited inactivation of isolated cytochrome P-450LM2 and induced hemoprotein formation after administration into rats. The preparations of glycyrrhizic acid appear to be useful for treatment of toxic impairment of liver tissue.
Asunto(s)
Antioxidantes , Inhibidores Enzimáticos del Citocromo P-450 , Ácido Glicirretínico/análogos & derivados , Microsomas Hepáticos/enzimología , Animales , Sistema Enzimático del Citocromo P-450/biosíntesis , Sistema Enzimático del Citocromo P-450/metabolismo , Inducción Enzimática , Ácido Glicirretínico/administración & dosificación , Ácido Glicirretínico/metabolismo , Ácido Glicirretínico/farmacología , Ácido Glicirrínico , Técnicas In Vitro , Inyecciones Intraperitoneales , Mediciones Luminiscentes , Masculino , Microsomas Hepáticos/efectos de los fármacos , Microsomas Hepáticos/metabolismo , RatasRESUMEN
2,2'-Phthaloyl-, 2,2'-isophthaloyl, and 2,2'-terephthaloyl-boff++[1,1,1-trimethylhydrazinium] dihydroxide, bis(inner salts) 7, 8, and 9 and their hydrazide and hydrazinium diiodide precursors were synthesized and tested for toxicity and their ability to block sympathetic ganglionic transmission. Only the 2,2'-phthaloyl and isophthaloylhydrazinium diiodides 4 and 5 produced weak inhibition of nerve transmission (35% at 2.15 X 10(-3) M). The inner salts were appreciably less toxic than the hydrazinium diiodides in brine shrimp testing. The log P (log10, chloroform pH 7 buffer system) values of all compounds were determined and those of the inner salts and hydrazinium diiodides were in the range of -3.03 to -3.60.
Asunto(s)
Bloqueadores Ganglionares/síntesis química , Hidrazinas/síntesis química , Ácidos Ftálicos/síntesis química , Transmisión Sináptica/efectos de los fármacos , Animales , Fenómenos Químicos , Química , Decápodos , Bloqueadores Ganglionares/farmacología , Bloqueadores Ganglionares/toxicidad , Hidrazinas/farmacología , Hidrazinas/toxicidad , Técnicas In Vitro , Ácidos Ftálicos/farmacología , Ácidos Ftálicos/toxicidad , Ratas , SolubilidadRESUMEN
The N-2 atoms of phosphorus 2,2-dimethylhydrazides, contrary to a previous report, can be methylated by iodomethane. Treatment of the resulting dihydrazinium iodides with aqueous sodium hydroxide results in mono- instead of didehydroiodination, apparently due to resonance stabilization of the inner salt form. The phosphaminimide products and their hydrazinium iodide precursors blocked sympathetic ganglionic transmission while one dihydrazide intermediate produced potentiation. Brine shrimp testing indicated that conversion of a hydrazinium iodide to an aminimide moiety results in decreased toxicity.
Asunto(s)
Ganglios Simpáticos/efectos de los fármacos , Bloqueadores Ganglionares/síntesis química , Hidrazinas/síntesis química , Compuestos Organofosforados/síntesis química , Animales , Artemia , Hidrazinas/farmacología , Hidrazinas/toxicidad , Técnicas In Vitro , Dosificación Letal Mediana , Compuestos Organofosforados/farmacología , Compuestos Organofosforados/toxicidad , Ratas , Ratas Endogámicas , Relación Estructura-ActividadRESUMEN
Anthryl-labeled fluorescent probes closely mimicking phosphatidylcholine and sphingomyelin were applied to study the state of these phospholipids in the rabbit erythrocyte membrane. At normal cholesterol levels both probes exhibited higher fluorescence polarization values in the membranes than in phospholipid vesicles of similar lipid composition, indicating a decreased fluidity of the probe environment in erythrocyte ghosts. In ghosts prepared from normal erythrocytes no evidence of lateral separation of phosphatidylcholine and sphingomyelin was found. At higher cholesterol levels, however, these lipids appear to segregate. Probably the effect of cholesterol on the erythrocyte membrane lipids involves lipid-protein interactions. At physiological concentrations, prostaglandin E1 only weakly affects the state of phosphatidylcholine and sphingomyelin in erythrocyte membranes. Cholesterol enrichment amplifies the effect of prostaglandin E1. Although the prostaglandin E1-induced changes depended much upon whether the ghosts were enriched with cholesterol in vitro or in vivo, with both types of ghosts effects of prostaglandin E1 were seen at extremely low effector concentrations that may have presented a few molecules of prostaglandin per ghost. The structural and functional significance of these findings is discussed.
Asunto(s)
Colesterol/farmacología , Membrana Eritrocítica/ultraestructura , Lípidos de la Membrana/sangre , Fosfolípidos/sangre , Prostaglandinas E/farmacología , Alprostadil , Animales , Colesterol/sangre , Membrana Eritrocítica/efectos de los fármacos , Colorantes Fluorescentes , Masculino , Lípidos de la Membrana/aislamiento & purificación , Fosfolípidos/aislamiento & purificación , Conejos , Espectrometría de FluorescenciaRESUMEN
DL-l-Amino-l-methyl-3-carboxypropanephosphinic acid, a bioisostere of α-methylglutamic acid, was synthesized. This compound, the corresponding α-methylaspartic acid analogue and their precursors were tested for antibacterial activity. The methylaspartic acid analogue gave a MIC of 400 and 800 µg/ml against B. subtilis and P. aeroginosa, respectively.
RESUMEN
An alpha-phosphino analogue of alpha-methylaspartate has been synthesized. The compound may not interact with excitatory amino acid receptors directly, as assessed by direct in vitro radioreceptor binding methods; however, it possesses weak anticonvulsant activity and exhibits an excitant action in vitro that is apparently not mediated by a N-methyl-D-aspartate receptor.
Asunto(s)
Alanina/análogos & derivados , Compuestos Organofosforados/síntesis química , Receptores de Superficie Celular/metabolismo , Acetilcolina/metabolismo , Alanina/síntesis química , Alanina/farmacología , Animales , Anticonvulsivantes/síntesis química , Ácido Aspártico/metabolismo , Cerebelo/metabolismo , Cuerpo Estriado/metabolismo , Electrochoque , Glutamatos/metabolismo , Ácido Glutámico , Técnicas In Vitro , Compuestos Organofosforados/farmacología , Pentilenotetrazol/farmacología , Ratas , Receptores de Aminoácidos , Sinaptosomas/metabolismoRESUMEN
A series of phosphorus compounds, designed as analogues of gamma-aminobutyric acid (GABA) in that they possess a P = O moiety separated by three atoms from an amino or acetamido group, was synthesized and tested by using in vitro GABAA and GABAB receptor binding, GABA uptake assays, and was examined for anticonvulsant activity. Weak GABAB receptor affinity was noted for one agent, whereas six compounds displayed moderate to high potencies as inhibitors of electroshock- and pentylenetetrazol-induced seizures. The best anticonvulsant effect was found with the (m-aminophenyl) phosphinic acid compounds, with members of this class selected for further study.
Asunto(s)
Anticonvulsivantes/síntesis química , Compuestos Organofosforados/síntesis química , Ácido gamma-Aminobutírico/análogos & derivados , Animales , Bioensayo , Encéfalo/metabolismo , Indicadores y Reactivos , Espectroscopía de Resonancia Magnética , Ratones , Compuestos Organofosforados/farmacología , Compuestos Organofosforados/uso terapéutico , Ratas , Receptores de Superficie Celular/efectos de los fármacos , Receptores de Superficie Celular/metabolismo , Receptores de GABA-A , Convulsiones/tratamiento farmacológico , Espectrofotometría Infrarroja , Relación Estructura-Actividad , Sinaptosomas/efectos de los fármacos , Sinaptosomas/metabolismo , Ácido gamma-Aminobutírico/síntesis química , Ácido gamma-Aminobutírico/metabolismo , Ácido gamma-Aminobutírico/farmacología , Ácido gamma-Aminobutírico/uso terapéuticoRESUMEN
Diethylstilbestrol, psoralen, and propranolol were used as potential carrier molecules for selective concentrations of a nitrogen mustard moiety in breast, skin, and lung tissues, respectively. The propranolol derivative gave two racemic mixtures, which were tested to ascertain any differences in anticancer activity. The insertion of a P = O group between the carrier and oncolytic portions offsets the excess lipophilic contribution of the latter and possibly provides for latentiation of alkylating activity. Murine tumor testing of the phosphoramide mustard derivatives and two intermediates indicated that two compounds possessed marginal activity against mammary carcinoma and lymphocytic leukemia.
Asunto(s)
Compuestos de Mostaza Nitrogenada/administración & dosificación , Animales , Dietilestilbestrol/metabolismo , Formas de Dosificación , Ficusina/metabolismo , Leucemia Experimental/tratamiento farmacológico , Neoplasias Pulmonares/tratamiento farmacológico , Neoplasias Mamarias Experimentales/tratamiento farmacológico , Ratones , Modelos Moleculares , Propranolol/metabolismo , Difracción de Rayos XRESUMEN
Age-dependent alterations of plasmatic membranes were studied in rabbit erythrocytes after separation of erythrocytes of various age by means of centrifugation. The membrane structure characteristics were studied using a fluorescent probe pyrene and spin-labelled probes--nitroxyl derivatives of stearic acid and carboline derivatives. Microviscosity of the membrane lipid phase was shown to increase depending on the cell age. Alterations in the membrane structure were accompanied by a decrease in activity of Na-, K+-ATPase. The content and ratio of membrane lipids were altered with an increase in the cell age, which could be one of reasons of the membrane microviscosity elevation. The age-dependent alterations in erythrocyte membranes may be related, firstly, to the mechanism of old erythrocyte elimination from circulation and, secondly, to be the common characteristic for cell ageing, according to the "membrane hypothesis" of ageing.