Effect of Mg-Gluconate on the Osmotic Fragility of Red Blood Cells, Lipid Peroxidation, and Ca2+-ATPase (PMCA) Activity of Placental Homogenates and Red Blood Cell Ghosts From Salt-Loaded Pregnant Rats.

Preeclampsia (PE) is a pregnancy-specific syndrome with multisystem involvement which leads to fetal, neonatal, and maternal morbidity and mortality. A model of salt-loaded pregnant rats has been previously studied, sharing several pathological characteristics of preeclamptic women. In this study, it was compared the effects of the treatment with an oral magnesium salt, magnesium gluconate (Mg-gluconate), on the osmotic fragility of red blood cells, lipid peroxidation, and PMCA activity of placental homogenates and red blood cell ghosts in salt-loaded pregnant rats. Mg-gluconate has a higher antioxidant capacity than MgSO4 due to the presence of several hydroxyl groups in the two anions of this salt. Salt-loaded pregnant rats received 1.8% NaCl solution ad libitum as a beverage during the last week of pregnancy. On day 22nd of pregnancy, the rats were euthanized and red blood cells and placenta were obtained. Salt-loaded pregnant rats showed an increased level of lipid peroxidation and a lowered PMCA activity in placental and red blood cell ghosts, as well as an increased osmotic fragility of their red blood cells. The treatment of the salt-loaded pregnant rats with Mg-gluconate avoids the rise in the level of lipid peroxidation and the concomitant lowering of the PMCA activity of their red blood cell membranes, reaching values similar to those from control pregnant rats. Also, this treatment prevents the increase of the osmotic fragility of their red blood cells, keeping values similar to those from control pregnant rats. Mg-gluconate seems to be an important candidate for the replacement of the MgSO4 treatment of preeclamptic women.

Effect of magnesium sulfate in oxidized lipid bilayers properties by using molecular dynamics.

Magnesium sulfate (MgSO4) has been used as a protector agent for many diseases related to oxidative stress. The effect of MgSO4 on the oxidized lipid bilayer has not yet been studied using molecular dynamics calculations. In this work, the effects of oxidation were evaluated by using a POPC membrane model at different concentrations of its aldehyde (-CHO) and hydroperoxide (-OOH) derivatives with and without MgSO4. Several quantitative and qualitative properties were evaluated, such as membrane thickness, area per lipid, area compressibility modulus, snapshots after simulation finish, density distributions, time evolutions of oxidized group positions, and radial distributions of oxidized group concerning Mg. Results indicate that in the absence of MgSO4 the mobility of oxidized groups, particularly -CHO, toward the surface interface is high. At a low oxidation level of the bilayer there is an increase in the compressibility modulus as compared to the unoxidized bilayer. MgSO4, at a low oxidation level, tends to lessen the oxidation effects by lowering the dispersion in the distribution of oxidized species toward the membrane surface and the water region. However, MgSO4 does not change the trends of decreasing membrane thickness and area compressibility modulus and increasing area per lipid upon oxidation. In this regard, MgSO4 diminishes the electrostatic long-distance attractive interactions between the oxidized groups and the charged headgroups of the interface, owing to the Mg+2 and SO4 -2 screening effects and an electrostatic stabilization of the headgroups, preventing the pore formation, which is well-known to occur in oxidized membranes.

Mechanisms of the effect of magnesium salts in preeclampsia.

Preeclampsia is a heterogeneous pregnancy-specific syndrome associated with abnormal trophoblast invasion and endothelial dysfunction. Magnesium (Mg2+) level may be normal or decreased in women with preeclampsia. However, the use of Mg2+ salts, such as Mg2+ sulphate, are useful in reducing the pathophysiological consequences of preeclampsia with severe features and eclampsia. Although the mechanism of action of this Mg2+ salt is not well understood, the available evidence suggests a beneficial effect of Mg2+ for the mother and foetus. The mechanisms include a lower level of soluble fms-like tyrosine kinase 1 and endoglin, blockage of brain N-methyl-D-aspartate receptors, decreased inflammation mediators, activation of nitric oxide synthases, blockage of arginases, and reduced free radicals level. The maintenance of Mg2+ homeostasis in pregnancy is crucial for an appropriate pregnancy progression. Oral Mg2+ salts can be used for this purpose which could result in mitigating the deleterious consequences of this syndrome to the mother, foetus, and newborn.

Osmotic fragility of red blood cells, lipid peroxidation and Ca²âº-ATPase activity of placental homogenates and red blood cell ghosts in salt-loaded pregnant rats.

OBJECTIVE: To evaluate the osmotic fragility of red blood cells and the level of lipid peroxidation, the Ca(2+)-ATPase activity of red cell ghosts and placental homogenates from salt-loaded pregnant rats. METHODS: Salt-loaded pregnant rats received 1.8% NaCl solution ad libitum as a beverage for seven days, starting on 15th day of pregnancy. Then, it was evaluated the level of lipid peroxidation and the Ca(2+)-ATPase activity of placental homogenates and red blood cell ghosts from control and experimental rats. Furthermore, the osmotic fragility of the red blood cells was evaluated by measuring the lysis of these cells when incubated with a NaCl solution with different osmolarities. RESULTS: It was found that placental homogenates and red blood cell ghosts from experimental pregnant rats showed an increased level of lipid peroxidation and a lowered Ca(2+)-ATPase activity, as compared to control pregnant rats. They also presented an increased osmotic fragility of their red blood cells. CONCLUSIONS: Salt-loaded pregnant rats showed, similar to preeclamptic women, an increased level of lipid peroxidation and a lowered Ca(2+)-ATPase activity in placental and red blood cells membranes, as well as an increased osmotic fragility of the red blood cells.

ATPases, ion exchangers and human sperm motility.

Human sperm has several mechanisms to control its ionic milieu, such as the Na,K-ATPase (NKA), the Ca-ATPase of the plasma membrane (PMCA), the Na(+)/Ca(2) (+)-exchanger (NCX) and the Na(+)/H(+)-exchanger (NHE). On the other hand, the dynein-ATPase is the intracellular motor for sperm motility. In this work, we evaluated NKA, PMCA, NHE, NCX and dynein-ATPase activities in human sperm and investigated their correlation with sperm motility. Sperm motility was measured by Computer Assisted Semen Analysis. It was found that the NKA activity is inhibited by ouabain with two Ki (7.9 × 10(-9) and 9.8 × 10(-5) M), which is consistent with the presence of two isoforms of α subunit of the NKA in the sperm plasma membranes (α1 and α4), being α4 more sensitive to ouabain. The decrease in NKA activity is associated with a reduction in sperm motility. In addition, sperm motility was evaluated in the presence of known inhibitors of NHE, PMCA and NCX, such as amiloride, eosin, and KB-R7943, respectively, as well as in the presence of nigericin after incubation with ouabain. Amiloride, eosin and KB-R7943 significantly reduced sperm motility. Nigericin reversed the effect of ouabain and amiloride on sperm motility. Dynein-ATPase activity was inhibited by acidic pH and micromolar concentrations of Ca(2) (+). We explain our results in terms of inhibition of the dynein-ATPase in the presence of higher cytosolic H(+) and Ca(2) (+), and therefore inhibition of sperm motility.

Na⁺, K⁺-ATPase and Ca²âº-ATPase activities in basal and microvillous syncytiotrophoblast membranes from preeclamptic human term placenta.

OBJECTIVE: The aim of this study is to evaluate the effect of preeclampsia on the level of lipid peroxidation, activity and expression of both plasma membrane Ca(2+)- and Na(+), K(+)-ATPases in syncytiotrophoblast. METHODS: The level of lipid peroxidation was estimated by measuring TBARS. ATPase activities were quantified by a colorimetric method measuring the amount of inorganic phosphate during the assay. Expression of Ca(2+)- and Na(+), K(+)-ATPases in syncytiotrophoblast plasma membranes and term placenta tissue sections was investigated using Western blot and immunohistochemistry, respectively. RESULTS: Our results show a higher level of lipid peroxidation of syncytiotrophoblast plasma membranes from preeclamptic, as compared to uncomplicated pregnant women. Preeclampsia also significantly reduced the activity of Ca(2+)- and Na(+), K(+)-ATPases; however, expression of both ATPases was unaffected. CONCLUSION: Our findings suggest that the reduction of Ca(2+)- and Na(+), K(+)-ATPase activities during preeclampsia could be at least partially due to an increased level of lipid peroxidation of the syncytiotrophoblast plasma membranes.

Effect of hypoxia on the calcium and magnesium content, lipid peroxidation level, and Ca²âº-ATPase activity of syncytiotrophoblast plasma membranes from placental explants.

In the current study the possible relationship between the Ca(2+)/Mg(2+) ratio of human syncytiotrophoblast plasma membranes and their lipid peroxidation and Ca(2+)-ATPase activity was determined. Syncytiotrophoblast plasma membranes of placental explants cultured under hypoxia increased their lipid peroxidation and Ca(2+) content, diminished their Ca(2+)-ATPase activity, and kept their Mg(2+) content unchanged. Membranes preincubated with different concentrations of Ca(2+) increased their Ca(2+) content without changes in their Mg(2+) content. There is a direct relationship between Ca(2+) content and lipid peroxidation of the membranes, as well as an inverse relationship between their Ca(2+) content and Ca(2+)-ATPase activity. On the contrary, preincubation of membranes with different concentrations of Mg(2+) showed a higher Mg(2+) content without changing their lipid peroxidation and Ca(2+)-ATPase activity. Explants cultured under hypoxia in the presence of 4 mM MgSO4 showed similar values of lipid peroxidation and Ca(2+)-ATPase activity of their membranes compared to those of explants cultured under normoxia. Increased Ca(2+) content of the membranes by interacting with negatively charged phospholipids could result in destabilizing effects of the membrane structure, exposing hydrocarbon chains of fatty acids to the action of free radicals. Mg(2+) might exert a stabilizing effect of the membranes, avoiding their exposure to free radicals.

Preeclampsia, placenta, oxidative stress, and PMCA.

OBJECTIVE: The aim of this study is to summarize the reported evidence on the possible relationship between preeclampsia, placenta, oxidative stress and plasma membrane Ca-ATPase (PMCA) activity, responsible for fine control of intracellular calcium concentration. METHODS: Literature search was conducted in MEDLINE/PubMed and several unpublished results from our laboratory were included. RESULTS: Lipid peroxidation in placental and red blood cell plasma membranes during preeclampsia and a concomitant diminution of their PMCA activity are described. CONCLUSIONS: Uteroplacental hypoperfusion raises lipid peroxidation by-products in the blood plasma that could alter structure and functionality of the cell membranes of the endothelium and several tissues.

Effect of ultraviolet C irradiation on human sperm motility and lipid peroxidation.

PURPOSE: Ultraviolet C (UVC) irradiation of aqueous solutions is known to be a good source of reactive oxygen species (ROS). The aim of this study is to examine the effect of increasing doses of UVC irradiation, in the presence and absence of the antioxidant butylated hydroxytoluene (BHT), on human sperm motility and lipid peroxidation of its membranes. MATERIALS AND METHODS: Human sperm samples were irradiated with UVC light (254 nm) for different periods of time. A computer-assisted semen analysis of sperm motility was carried out after UV irradiation. The percentage of motile sperm (%MOT), progressive motility, straight line velocity (VSL), curvilinear velocity (VCL) and the percentage of linearity (%LIN) were evaluated. The level of lipid peroxidation of sperm membranes was estimated by measurement of the thiobarbituric acid reactive substances (TBARS). RESULTS: UVC irradiation of human spermatozoa produced a diminution of the sperm motility (%MOT, progressive motility, VSL, VCL, %LIN), viability and, concomitantly, an increase of the level of lipid peroxidation of the sperm membranes. The observed effects of the UVC irradiation were prevented by addition of the antioxidant BHT, indicating that the effects of UVC on the tested sperm parameters are mediated by an important rise in lipid peroxidation of the sperm membrane. CONCLUSION: Lipid peroxidation of the human sperm plasma membrane leads to a decrease in the sperm motility (%MOT, progressive motility, VSL, VCL, %LIN) and viability. The protective effect of BHT on the UVC-irradiated sperm cells indicates the effects of ROS on sperm function.

Trypanosoma evansi: Effect of experimental infection on the osmotic fragility, lipid peroxidation and calcium-ATPase activity of rat red blood cells.

Trypanosoma evansi is the causative agent of equine trypanosomoses. The disease is characterized by fever, anemia, and cachexia. Peroxidative damage of the red blood cells caused by the parasite, may contribute to the pathogenesis of the anemia seen in trypanosomoses. Consequently, we evaluated the hematocrit, the osmotic fragility of the red blood cells, the level of lipid peroxidation and the activity of the Ca-ATPase of red blood cell ghosts from rats experimentally infected with T. evansi. After 72 h inoculation, the hematocrit decreased from 49.5% to 33%; the osmotic fragility of the red blood cells was approximately 40% higher as compared to the healthy animals; and the red blood cell ghosts showed a higher level of lipid peroxidation and a lower Ca-ATPase activity than the red cell ghosts from the healthy animals. In vitro incubations of red blood cells from healthy animals with T. evansi, produced also a significant increase of the osmotic fragility of the red blood cells.

Effect of magnesium sulfate on the osmotic fragility and lipid peroxidation of intact red blood cells from pregnant women with severe preeclampsia.

OBJECTIVE: To evaluate the osmotic fragility and level of lipid peroxidation of red blood cells from pregnant women with severe preeclampsia, treated or not with MgSO(4). METHODS: Osmotic fragility and lipid peroxidation of red blood cells was evaluated in 11 normotensive pregnant women and eleven pregnant women with severe preeclampsia. RESULTS: MgSO(4) therapy, either in vivo or in vitro, leads to a reduction of the osmotic fragility and the level of lipid peroxidation of red blood cells from pregnant women with severe preeclampsia. CONCLUSIONS: Interaction of MgSO(4) with free radicals, by avoiding an excessive lipid peroxidation of the red blood cell membrane, would protect the membrane structure, avoiding in this way the increase in osmotic fragility.

Biochemical identification of dynein-ATPase activity in human sperm.

Dynein-ATPase is the intracellular motor for sperm motility. In the present work we assayed the dynein-ATPase activity in an axoneme-containing fraction of human sperm, free of plasma membranes, in normozoospermic and asthenozoospermic donors. Axoneme-containing fractions were isolated from semen samples obtained from healthy donors with either normozoospermia or asthenozoospermia, as indicated by a sperm motility lower than 50% (WHO grade a + b). The dynein-ATPase activity was assayed and partially characterized. The dynein-ATPase activity in the axoneme-containing fractions was identified as Mg2+-dependent ATPase activity inhibited by 10 microM vanadate. This inhibition was not seen when the assay was done in the presence of 1 mM norepinephrine. The dynein-ATPase activity is Mg2+-dependent, Li+-sensitive, and insensitive to 2 mM ouabain, 1 microM oligomycin, and 1 microM thapsigargin. The dynein-ATPase activity was significantly lower (p < 0.001) for asthenozoospermic donors as compared to normozoospermic donors. This is a straightforward dynein-ATPase assay that can be used to obtain data of functional interest in clinical or experimental settings.

Ca-ATPase activity of human red cell ghosts: preeclampsia, lipid peroxidation and MgSO4.

The increased level of lipid peroxidation of red blood cells during preeclampsia is considered to be responsible for the diminished Ca-ATPase activity in these cells. The level of lipid peroxidation and the Ca-ATPase activity of red blood cells from preeclamptic women, return to their normal values after in vivo and in vitro treatment with MgSO4 for 24 h. In order to evaluate whether or not cell intactness is essential for these changes, we used either intact red blood cells or red cell ghosts from normotensive pregnant women. The intact red blood cells were treated with Fenton's reagent and then incubated with 4 mM MgSO4. The red cells ghosts were irradiated with UV light and afterwards incubated with MgSO4 at 4 degrees C. Lipid peroxidation and Ca-ATPase activity were determined for all the preparations. Both, Fenton's reagent and UV irradiation increased the level of lipid peroxidation and diminished the Ca-ATPase activity of the red cell membranes. Incubation of the cells treated with Fenton's reagent, or the ghosts irradiated with UV, with 4 mM MgSO4, returned Ca-ATPase activity and lipid peroxidation levels to normal values. The presence of MgSO4 blocked the effects in the ghosts of UV irradiation. MgSO4 seems to better protect the red cell membrane against lipid peroxidation than other SO4= and Cl- salts. These results indicate that the changes in the lipid peroxidation of the red cell ghosts and their Ca-ATPase activity are a result of changes to the cell membranes.

On the functional use of the membrane compartmentalized pool of ATP by the Na+ and Ca++ pumps in human red blood cell ghosts.

Previous evidence established that a sequestered form of adenosine triphosphate (ATP pools) resides in the membrane/cytoskeletal complex of red cell porous ghosts. Here, we further characterize the roles these ATP pools can perform in the operation of the membrane's Na(+) and Ca(2+) pumps. The formation of the Na(+)- and Ca(2+)-dependent phosphointermediates of both types of pumps (E(Na)-P and E(Ca)-P) that conventionally can be labeled with trace amounts of [gamma-(3)P]ATP cannot occur when the pools contain unlabeled ATP, presumably because of dilution of the [gamma-(3)P]ATP in the pool. Running the pumps forward with either Na(+) or Ca(2+) removes pool ATP and allows the normal formation of labeled E(Na)-P or E(Ca)-P, indicating that both types of pumps can share the same pools of ATP. We also show that the halftime for loading the pools with bulk ATP is 10-15 minutes. We observed that when unlabeled "caged ATP" is entrapped in the membrane pools, it is inactive until nascent ATP is photoreleased, thereby blocking the labeled formation of E(Na)-P. We also demonstrate that ATP generated by the membrane-bound pyruvate kinase fills the membrane pools. Other results show that pool ATP alone, like bulk ATP, can promote the binding of ouabain to the membrane. In addition, we found that pool ATP alone functions together with bulk Na(+) (without Mg(2+)) to release prebound ouabain. Curiously, ouabain was found to block bulk ATP from entering the pools. Finally, we show, with red cell inside-outside vesicles, that pool ATP alone supports the uptake of (45)Ca by the Ca(2+) pump, analogous to the Na(+) pump uptake of (22)Na in this circumstance. Although the membrane locus of the ATP pools within the membrane/cytoskeletal complex is unknown, it appears that pool ATP functions as the proximate energy source for the Na(+) and Ca(2+) pumps.

Sperm lipid peroxidation and pro-inflammatory cytokines.

AIM: To investigate if interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-10 (IL-10), interferon-gamma (IFN-gamma) or tumor necrosis factor-alpha (TNF-alpha) are able to stimulate the level of lipid peroxidation of sperm membranes, either alone or in the presence of leukocytes. METHODS: Semen samples from normozoospermic donors were prepared by density gradient. The sperms were exposed to the indicated cytokines, at physiological and infection-inflammation concentrations, in the absence or presence of leukocytes. Lipid peroxidation of the sperm membranes was determined by measuring malondialdehyde (MDA) and 4-hydroxialkenals (HAE) formation. RESULTS: TNF-alpha, IL-8 and IFN-gamma increased the level of sperm membrane lipid peroxidation when tested at physiological concentrations. At infection-inflammation concentrations, only IL-8 was able to produce a higher effect. When assayed in the presence of leucocytes, IL-8 and TNF-alpha showed a higher effect at infection-inflammation concentrations than at physiological concentrations. Finally, IL-8 showed a higher effect in the presence of leukocytes than in their absence at both physiological and infection-inflammation concentrations. TNF-alpha also showed a higher effect when assayed in the presence of leukocytes than in their absence, but only at infection-inflammation concentrations. There was no effect of IL-6 or IL-10 in any of the tested conditions. CONCLUSION: Several pro-inflammatory cytokines at physiological concentrations increase the level of lipid peroxidation of sperm membranes, which could be important for the sperm fecundation process. However, infection-inflammation concentrations of some cytokines, such as IL-8 and TNF-alpha, either alone or in the presence of leukocytes, could drive the lipid peroxidation of the spermatozoa plasma membrane to levels that can affect the sperm fertility capacity.

The plasma membrane Ca2+-ATPase protein from red blood cells is not modified in preeclampsia.

Plasma membrane Ca2+-ATPase activity diminishes by about 50% in red blood cells during preeclampsia. We investigated whether the number of Ca2+-ATPase molecules is modified in red cell membranes from preeclamptic pregnant women by measuring the specific phosphorylated intermediate of this enzyme. Also, we isolated the Ca2+-ATPase protein from both normotensive and preeclamptic pregnant women and estimated its molecular weight, and its cross-reactions with specific polyclonal and monoclonal (5F10) antibodies against it. We measured the Ca2+-ATPase activity in a purified state and the effect of known modulators of this ATPase. It was found that the phosphorylated intermediate associated with PMCA is similar for red cell ghosts from normotensive and preeclamptic women, suggesting a similar number of ATPase molecules in these membranes. The molecular weight of the Ca2+-ATPase is around 140 kDa for both normotensive and preeclamptic membranes, and its cross-reactions with specific antibodies is similar, suggesting that the protein structure remains intact in preeclampsia. Calmodulin, ethanol, or both calmodulin plus ethanol, stimulated the Ca2+-ATPase activity to the same extent for both normotensive and preeclamptic preparations. Our results showed that the reduced Ca2+-ATPase activity of the red cell membranes from preeclamptic women is not associated with a defective enzyme, but rather with a high level of lipid peroxidation.

Lipid peroxidation and Ca-ATPase activity of basal plasma membranes of syncytiotrophoblast from normotensive pregnant women.

BACKGROUND: The Ca-ATPase activity of the plasma membranes of several tissues of preeclamptic pregnant women is significantly reduced when compared with the values of normotensive pregnant women. This has been explained considering the raise in the level of lipid peroxidation of the plasma membranes with preeclampsia. In this work we studied the effect of lipid peroxidation of syncytiotrophoblast basal (fetal facing) plasma membranes from normotensive pregnant women, on their level of Ca-ATPase activity. METHODS: The syncytiotrophoblast basal (fetal facing) plasma membranes from normotensive pregnant women were isolated and irradiated with ultraviolet (UV) light (254 nm). The membranes were then assayed for Ca-ATPase activity and lipid peroxidation by TBARS. RESULTS: The UV irradiation raises the level of lipid peroxidation of the membranes, producing a concomitant inhibition of their Ca-ATPase activity. Presence of the antioxidant butylated hydroxytoluene during the UV irradiation of the membranes prevents increase in their level of lipid peroxidation and hence the inhibition of their Ca-ATPase activity. CONCLUSION: These results give a strong support to the hypothesis that the lowered Ca-ATPase activity already described for plasma membranes of several tissues of preeclamptic women is the consequence of the increased level of lipid peroxidation shown by these membranes.

Effect of magnesium sulfate on the calcium-stimulated adenosine triphosphatase activity and lipid peroxidation of red blood cell membranes from preeclamptic women.

The effect of the treatment with magnesium sulfate (MgSO(4)) on Ca-ATPase activity and level of lipid peroxidation of red blood cells from preeclamptic pregnant women was examined because it is known that these parameters are affected with preeclampsia. Red cell ghosts from 11 normotensive and 11 preeclamptic pregnant women, before and after treatment with MgSO(4), were assayed for Ca-ATPase activity and level of lipid peroxidation, determined as TBARS or conjugated dienes. It was found that the Ca-ATPase activity is significantly lower and the level of lipid peroxidation is significantly higher in the preeclamptic women with no treatment, as compared to normotensive pregnant women. Both parameters return to normal values after the MgSO(4) therapy. These results can be mimicked by in vitro preincubation with MgSO(4) of intact red blood cells from preeclamptic pregnant women, without any treatment. Our data indicate that MgSO(4) treatment of preeclamptic pregnant women modifies both the Ca-ATPase activity and the level of lipid peroxidation of their red blood cell membranes, reaching values similar to those of normotensive pregnant women. The diminution of the level of lipid peroxidation by MgSO(4), can account for the increase in Ca-ATPase activity.

Sulfato de magnesio ¿una panacea? / Magnesium sulfate: a panace?

El magnesio es un catión importante que juega un rol esencial en muchas funciones fisiológicas como: procesos metabólicos que requieren energía; síntesis de proteínas; mantenimiento de la integridad de membranas celulares y subcelulares; excitabilidad neuromuscular y, contracción muscular. La principal fuente de Mg es la dieta y los órganos responsables de mantener las concentraciones plasmáticas de Mg dentro de los límites normales son el intestino delgado y el riñón. El Mg actualmente es empleado para fines terapéuticos y se administra en forma de sales, entre las cuales cabe destacar al sulfato de Mg. Esta sal posee una gran variedad de efectos benéficos sobre el organismo, entre los cuales podemos mencionar un efecto antioxidante, propiedades neuro y cardioprotectoras, efecto anticonvulsivante, propiedades broncodilatadoras y efectos vasodilatadores, entre otras. En los últimos años, el uso del sulfato de Mg para fines terapéuticos ha tomado considerable auge y pareciera representar una panacea en el área clínica. Así, el sulfato de Mg es administrado para una gran cantidad de desórdenes clínicos, entre los cuales podemos destacar: preeclampsia y partos pre-términos, desórdenes cardiovasculares, procesos de isquemia cerebral, asma, migrañas, y síndrome Irukandji entre otros. Al ser administrado en las concentraciones consideradas como terapéuticas, basadas en la experiencia clínica, el sulfato de Mg posee mínimos efectos tóxicos

Efecto del etanol sobre las actividades de ATPasas de Na+ y de Na+, K+ de membranas plasmáticas laterobasales de células de túbulo proximal de riñón de ratas viejas / Effect of ethanol on the Na+ and Na+, K+ ATPase activities of basolateral plasma membranes of kidney proximal tubular cells of old rats

Existen dos ATPasas estimuladas por sodio en las membranas de células de túbulo proximal renal: La ATPasa de Na+,K+ y la Na+. La actividad de ambas enzimas disminuye con el envejecimiento. OBJETIVO: Comparar el efecto del alcohol (etanol) sobre las enzimas mencionadas en ratas jóvenes y viejas. MATERIALES Y METODOS: Se prepararon homogenizados de corteza renal y fracciones enriquesidas en membranas plasmáticas laterobasales de células de túbulo proximal renal procedentes de ratas macho Sprague-Dawley jóvenes y viejas. Se determinó las actividades ATPásicas respectivas en las preparaciones mediante un método espectrofotométrico tanto en ausencia como en presencia de etanol. RESULTADOS: Se encontró que, mientras la ATPasa de sodio, potasio era menos sensible al etanol, la ATPasa de sodio era más sensible al etanol en ratas viejas comparadas con jóvenes. CONCLUSIONES:Los hallazgos indican una clara diferenciación entre las dos ATPasas y permiten especular que la ingestión continua de etanol podría influenciar con más fuerza el funcionamiento de la ATPasa de sodio en personas viejas que en jóvenes...