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Objective: The current work was undertaken to study the calcium adenosine triphosphatase activity of red blood cell membranes from pregnant women with preeclampsia., Study Design: Six normotensive and six preeclamptic pregnant women at 38 to 39 weeks of gestation were studied. The diagnosis of preeclampsia was made on the basis of blood pressure (> 140/90 mm Hg), proteinuria (> 0.5 gm of urinary protein per day), or edema. Hemoglobin-free red blood cell ghosts were prepared from the heparinized blood samples and were used to determine the calcium adenosine triphosphatase activity., Results: It was found that the calcium adenosine triphosphatase activity of preeclamptic women is diminished by about 50% compared with that of normotensive pregnant women., Conclusion: A diminution of the calcium adenosine triphosphatase activity of erythrocytes in preeclampsia might be an indication that the in vivo activity of the calcium pump of these cells is diminished, which could, in turn, drive the cells to increase their cytoplasmic free calcium concentration.

In the present work it was investigated the effect of 2% ethanol on the Na+ and on the Na+, K(+)-ATPase activities. The differential effect of the alcohol on the two ATPases (approximately 40% inhibition of the Na(+)-ATPase and approximately 10% inhibition of the Na+, K(+)-ATPase), is not due to a higher degree of denaturalization of the enzyme, nor to a faster effect of ethanol on the Na(+)-than on the Na+, K(+)-ATPase. Our results show that ethanol affects the selectivity of the Na+, K(+)-ATPase for Na+ and/or for K+, enhancing the Na+ affinity for the K+ sites, and/or reducing the K+ affinity for its own sites. This effect was not seen for the Na(+)-ATPase, indicating that 2% ethanol inhibits the two ATPases in a totally different way.

The present paper shows evidence indicating that one of the active mechanisms of sodium extrusion shown to be present in basolateral plasma membranes of the proximal tubular cells of mammalian kidney, the Na-pump (which extrudes sodium from the cells accompanied by chloride and water), is modulated in its activity by the cell volume. An increase of the cell volume, produces a concomitant increase of the activity of the Na-pump. On the other hand, the activity of the Na, K-pump, which extrudes sodium from the cells in exchange for potassium, is totally independent of the cell volume. The modulating effect of the cell volume on the activity of the Na-pump, can be either demonstrated under "in vitro" or "in vivo" conditions.

In the present paper we summarize the theoretical aspects of the process of lipid peroxidation of the plasma membranes from cells of animal tissues. Also, we review the activity of plasma membrane ATPases, i.e., The Na,K-, Na- and Ca-ATPases, and how this modulation could play a role in some diseases.

The present work evaluates the effect of lipid peroxidation on the ouabain-insensitive Na-ATPase of basolateral plasma membranes from rat kidney proximal tubular cells as an indirect way to study the lipid dependence of this enzyme. An inverse relationship between lipid peroxidation and Na-ATPase activity was found. This effect was due neither to a change in the optimal Km of the system for Na+ nor for the substrate Mg:ATP, nor the optimal pH value of the medium. The optimal temperature value, however, was shifted toward a higher value. There was also an increase of the apparent energy of activation in the region of temperatures above the transition point (20 degrees C) with increase in lipid peroxidation. Peroxidized membranes incubated with phosphatidylcholine from soybean restored their Na-ATPase activity. On the other hand, the Na-ATPase activity was sensitive to oleoly lysophosphatidylcholine. These results suggest that lipid peroxidation might be affecting the Na-ATPase activity through either an increase of peroxidized phospholipids, which might change the membrane fluidity of the lipid microenvironment of the ATPase molecules, or through a direct effect of lysophospholipids released during the lipid peroxidation.

The Na(+)- and the Na+,K(+)-ATPase activities of basolateral plasma membranes from rat kidney proximal tubular cells were affected differentially by ethanol. Moreover, at concentrations of ethanol that can be reached in vivo in the blood plasma (50 mM) there was a significant effect on the Na(+)-ATPase activity and practically no effect on the Na+,K(+)-ATPase activity.

1. Two Na(+)-stimulated ATPase activities were determined in gill homogenates from squid, shrimp and teleost fish; in kidney slice homogenates from teleost fish, bullfrog, toad, iguana, chicken, duck, rat, pig and cow, as well as in homogenates from rat small intestinal cells, brain cortex and liver slices. The two Na(+)-stimulated ATPase activities, the Na- and the Na,K-ATPase, showed a different behavior toward K+ and ouabain. 2. The ouabain-insensitive, K(+)-independent, Na-ATPase activity for all the studied homogenates was completely inhibited by 2 mM furosemide. 3. An increase in cell volume of the kidney, brain cortex and liver slice preparations, as well as of the rat small intestinal cells, produced a concomitant increase of the ouabain-insensitive Na-ATPase.

Rats chronically fed for 15 months with an isotonic NaCl solution show a volume increase of their kidney proximal tubular cells as well as of the ouabain-insensitive, Na-stimulated ATPase activity of basolateral plasma membranes from these cells. If the experimental rats are changed to tap water after 15 months of the high sodium diet, the results are partially reversed. Thus, the cell volume and the Na-ATPase activity of their basolateral plasma membranes decrease, reaching values closer to those of control rats. There is more Na+ and Cl- in the cells from rats under the high Na(+)-diet than in the cells from control rats. On the other hand, when the rats on the high sodium diet are changed to control conditions (drinking tap water), their Na+ and Cl- contents decrease, approaching control values. It is proposed that the Na-ATPase activity is modulated "in vivo" by the cell volume.

Proximal tubular cells from kidneys of male rats chronically fed with an isotonic NaCl solution, show a volume increase which is dependent on the length of the treatment with NaCl, when compared with control rats. Parallel to the cell volume increase, there is an increase of the ouabain-insensitive Na-ATPase activity, whereas the ouabain-sensitive Na,K-ATPase activity remains unchanged. These results establish a clear relationship between a chronic Na-diet, kidney cell volume and Na-ATPase activity.

The present work was undertaken to evaluate the distribution of the Na-ATPase activity in the different components of the rat kidney cortex. Suspensions of glomeruli, proximal and distal tubules were prepared following a collagenase digestion of outermost kidney cortex slices and a separation on a Percoll gradient. It was found that the Na-ATPase activity is higher in the fraction enriched in proximal tubules. The fraction enriched in glomeruli and in distal tubules show also a Na-ATPase activity, but it is lower.

As in most cells, intracellular pH regulation is fundamental for sperm physiology. Key sperm functions like swimming, maturation, and a unique exocytotic process, the acrosome reaction, necessary for gamete fusion, are deeply influenced by pH. Sperm pH regulation, both intracellularly and within organelles such as the acrosome, requires a coordinated interplay of various transporters and channels, ensuring that this cell is primed for fertilization. Consistent with the pivotal importance of pH regulation in mammalian sperm physiology, several of its unique transporters are dependent on cytosolic pH. Examples include the Ca2+ channel CatSper and the K+ channel Slo3. The absence of these channels leads to male infertility. This review outlines the main transport elements involved in pH regulation, including cytosolic and acrosomal pH, that participate in these complex functions. We present a glimpse of how these transporters are regulated and how distinct sets of them are orchestrated to allow sperm to fertilize the egg. Much research is needed to begin to envision the complete set of players and the choreography of how cytosolic and organellar pH are regulated in each sperm function. [ABSTRACT FROM AUTHOR]

Introduction: Sperm morphology analysis is very necessary to understand male fertility and the etiology of infertility. Currently, scanning electron microscopy (SEM) has been widely used to determine surface topology. In this study, we will compare the effects of spermatozoa cryopreservation using three different types of cryoprotectants, namely Nakagata, modification and Kitazato. The cryoprotectant compositions used are Nakagata (raffinose and skim milk), modified (glycerol and raffinose) and Kitazato (glycerol and trehalose). Methods: SEM analysis was carried out on 8 sperm samples before cryopreservation and after the freeze-thaw process. Results: The results obtain showed that cryoprotectant modification was able to protect spermatozoa morphology better than Nakagata and Kitazato. Analysis revealed damage to plasma membrane, acrosome and loss of mitochondria in all treatment groups compared to fresh sperm. SEM showed obvious signs of post-thaw damage such as missing plasma membranes, sperm showing damaged acrosomes and mitochondria in the middle showing structural disorganization. Conclusion: SEM revealed that cryopreservation caused ultrastructural damage to mice sperm due to freezing and thawing. These details provide valuable data for further research to minimize the damage caused by cryopreservation to mice sperm. Apart from that, further examination using TEM is recommended to obtain a more comprehensive picture. [ABSTRACT FROM AUTHOR]

Background: Mammalian spermatozoa have to be "capacitated" to be fertilization‐competent. Capacitation is a collective term for the physiological and biochemical changes in spermatozoa that occur within the female body. However, the regulatory mechanisms underlying capacitation have not been fully elucidated. Methods: Previously published papers on capacitation, especially from the perspective of ions/channels/transporters, were extracted and summarized. Results: Capacitation can be divided into two processes: earlier events (membrane potential hyperpolarization, intracellular pH rise, intracellular Ca2+ rise, etc.) and two major later events: hyperactivation and the acrosome reaction. Earlier events are closely interconnected with each other. Various channels/transporters are involved in the regulation of them, which ultimately lead to the later events. Manipulating the extracellular K+ concentration based on the oviductal concentration modifies membrane potential; however, the later events and fertilization are not affected, suggesting the uninvolvement of membrane potential in capacitation. Hyperpolarization is a highly conserved phenomenon among mammalian species, indicating its importance in capacitation. Therefore, the physiological importance of hyperpolarization apart from membrane potential is suggested. Conclusion: The hypotheses are (1) hyperpolarizing Na+ dynamics (decrease in intracellular Na+) and Na+‐driven secondary active transporters play a vital role in capacitation and (2) the sperm‐specific potassium channel Slo3 is involved in volume and/or morphological regulation. [ABSTRACT FROM AUTHOR]

Accumulation of heavy metals (Mn and Ni) and prolonged exposure to stress are associated with adverse health outcomes. Various studies have shown the impacts of stress and metal exposures on brain function. However, no study has examined the effects of co-exposure to stress, Mn, and Ni on the brain. This study addresses this gap by evaluating oxidative and glial responses, apoptotic activity, as well as cognitive processes in a rat model. Adult Wistar rats were exposed to vehicle (control), restraint stress, 25 mg/kg of manganese (Mn) or nickel (Ni), or combined restraint stress plus Mn or Ni. Following treatment, rats were subjected to several behavioural paradigms to assess cognitive function. Enzyme activity, as well as ATPase levels, were evaluated. Thereafter, an immunohistochemical procedure was utilised to evaluate neurochemical markers of glial function, myelination, oxidative stress, and apoptosis in the hippocampus, prefrontal cortex (PFC), and striatum. Results showed that stress and metal exposure increased oxidative stress markers and reduced antioxidant levels. Further, combined stress and metal exposure reduced various forms of learning and memory ability in rats. In addition, there were alterations in Iba1 activity and Nrf2 levels, reduced Olig2 and myelin basic protein (MBP) levels, and increased caspase-3 expression. These neurotoxic outcomes were mostly exacerbated by co-exposure to stress and metals. Overall, our findings establish that stress and metal exposures impaired cognitive performance, induced oxidative stress and apoptosis, and led to demyelination effects which were worsened by combined stress and metal exposure., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

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The present work was undertaken to evaluate whether changes in cell water content of rat kidney cortex cells can modulate the transport activity of the ouabain-insensitive Na pump as they modulate the ouabain-insensitive Na+-ATPase. It was found that there is a close relationship between the cell volume and activity of the Na pump, whereas Na,K-pump activity is not affected by variations in cell volume. When the cell water content is low, Na-pump activity (Na+ transport and Na+-ATPase activity) is minimal. Increases in cell water content produce a concomitant increase in Na-pump activity.

In this work, we present evidence in agreement with the hypothesis that there exist two Na+-stimulated ATPase activities in basolateral plasma membranes from rat kidney proximal tubular cells: (1) (Na+ + K+)-ATPase activity, which is inhibited by ouabain and by treating the membranes with trypsin, is insensitive to furosemide and reaches maximal activity upon treatment with SDS at an SDS/protein ratio of 1.6; (2) the Na+-ATPase activity, which is insensitive to ouabain and to trypsin treatment, is inhibited by furosemide and reaches maximal activity upon treatment with SDS at an SDS/protein ratio of 0.4.

The ouabain-insensitive, Mg2+-dependent, Na+-stimulated ATPase activity present in fresh basolateral plasma membranes from guinea-pig kidney cortex cells (prepared at pH 7.2) can be increased by the addition of micromolar concentrations of Ca2+ to the assay medium. The Ca2+ involved in this effect seems to be associated with the membranes in two different ways: as a labile component, which can be quickly and easily 'deactivated' by reducing the free Ca2+ concentration of the assay medium to values lower than 1 microM; and as a stable component, which can be 'deactivated' by preincubating the membranes for periods of 3-4 h with 2 mM EDTA or EGTA. Both components are easily activated by micromolar concentrations of Ca2+. The Ka of the system for Na+ is the same, 8 mM, whether only the stable component or both components, stable and labile, are working. In other words, the activating effect of Ca2+ on the Na+-stimulated ATPase is on the Vmax, and not on the Ka of the system for Na+. The activating effect of Ca2+ may be related to some conformational change produced by the interaction of this ion with the membranes, since it can also be obtained by resuspending the membranes at pH 7.8 or by ageing the preparations. Changes in the Ca2+ concentration may modulate the ouabain-insensitive, Na+-stimulated ATPase activity. This modulation could regulate the magnitude of the extrusion of Na+ accompanied by Cl- and water that these cells show, and to which the Na+-ATPase has been associated as being responsible for the energy supply of this mode of Na+ extrusion.

The ouabain-insensitive, Na+-stimulated ATPase activity of kidney proximal tubular cells from rats fed a high Na+ diet for 4 months was increased approximately 70% when compared with control (normal diet) rats. The higher ATPase activity was not due to a change in the affinity of the system toward ATP, Mg2+ or Na+. This increase in Na+-ATPase activity may be due to either a higher number of pumps or to a higher turnover rate of the enzyme or both. The ouabain-sensitive, Na+, K+-stimulated ATPase activity, on the other hand, did not change with the high sodium diet. These results can be taken as evidence that the Na+,K+-ATPase and the Na+-ATPase of basolateral plasma membranes of proximal tubular cells from rat kidney are two different entities.

The ouabain-insensitive, active Na+ uptake of inside-out vesicles prepared with basolateral plasma membranes from rat kidney proximal tubular cells can be increased by the presence of micromolar concentrations of Ca2+ in the assay medium. The concomitant ATP hydrolysis associated with the Na+ uptake is also increased by the presence of Ca2+. The Na+ uptake and the concomitant ATP hydrolysis are inhibited by 2 mM furosemide. The effect of Ca2+ is not due to the activity of an Na+-Ca2+ exchanger. The present results are in accordance with our previous model (Proverbio, F., Proverbio, T. and Marín, R. (1982) Biochim. Biophys. Acta 688, 757-763) in which we proposed that Ca2+ seems to modulate the activity of the ouabain-insensitive Na+ pump, in two different ways: (1) in a strong association with the membranes in which Ca2+ (stable component) is essential for the pump activity and (2) in a weak association with the membranes in which Ca2+ (labile component) can be quickly and easily removed by reducing the free Ca2+ concentration of the assay medium to values lower than 1 microM. The Ka for Ca2+ (for the labile component) is around 5 microM. The Ca2+ modulation of the ouabain-insensitive Na+ pump is an indication that Ca2+ could regulate the magnitude of the Na+ extrusion accompanied by Cl- and water present in rat kidney proximal tubular cells.

Inside-out vesicles prepared with basolateral plasma membranes from rat kidney proximal tubular cells can accumulate Na+ actively in two ways. Mode 1, which is K+-independent, is ouabain-insensitive and is inhibited by furosemide and mode 2, which is K+-dependent, is inhibited by ouabain and is insensitive to furosemide. The presence of Mg2+ and ATP in the incubation medium is essential for both modes of Na+ uptake to proceed and in both cases, the nucleotide is hydrolyzed during the process. These results are consistent with the idea of the existence, in these membranes, of two Na+ pumps: one, which can work in the absence of K+ (Na+ pump) and another, which needs K+ to work (Na+ + K+ pump).

Several characteristics of the Na+, K+-ATPase activity of basolateral plasma membranes of kidney proximal tubular cells from young (3 months) and old (24 months) rats were studied. In both cases, the ATPase activity reached optimum values under the following conditions: Mg2+:ATP concentrations (mM) 5:5 (apparent Km 0.5 mM); Na+ concentration 50 mM (apparent Km 18 mM); K+ concentration 20 mM (apparent Km 2.5 mM); pH 7.2; temperature 52 degrees. The values of the apparent energy of activation of the system were similar for young and old rats in the temperature range 20-52 degrees but were 55% higher for the old rats in the temperature range 10-20 degrees.

A ouabain-insensitive, K+-independent, sodium pump, has been demonstrated in guinea-pig and rat kidney proximal tubular cells. This pump is thought to be distinct from the ouabain-sensitive Na+/K+ pump. We present evidence here indicating the modulation of the biochemical expression of the Na+ pump, i.e. the ouabain-insensitive Na+-ATPase, by the cell volume in rat kidney proximal tubular cells. Thus, basolateral plasma membranes from swollen cells show a ouabain-insensitive Na+-ATPase activity 10-times higher than that in membranes from control cells. If the swollen cells recover their volume, the activity decreases ten times to control values. The ouabain-sensitive Na+/K+-ATPase is not affected by changes in the cell volume.

A method for preparation of highly purified basolateral plasma membranes from rat kidney proximal tubular cells is reported. These membranes were assayed for the presence of vesicles as well as for their orientation. (Na+ + K+)-ATPase activity and [3H]ouabain binding studies with membranes treated with or without SDS revealed that the preparation consisted of almost 100% vesicles. The percentage of inside-out vesicles was found to be approx. 70%. This percentage was determined measuring the (Na+ + K+)-ATPase activity in K+-loaded vesicles and in membranes treated with or without trypsin and SDS. These membranes represent a very efficient tool to assay the correlation between active transport and ATPase activities in basolateral plasma membranes from rat kidney proximal tubular cells.

Incubation of outermost rat kidney cortex slices (rich in proximal tubules) at 0 degrees C in a medium without K+ produces an increase in their cell water, Na+ and Cl- contents and a diminution in their cell K+ content. When these slices are rewarmed at 25 degrees C in a medium without K+, they can regulate their cell volume and their cell Na+ and Cl- contents. When the rewarming period lasts more than 30 min, there is again a cellular swelling, which seems to be correlated with the diminution of the cell K+ concentration. This effect of cellular K+ appears to be related to severe changes in cellular permeability to ions and water. The oxygen consumption and the cell ATP concentrations are similar to those in control conditions. The ouabain-insensitive Na-pump activity is not affected by different concentrations of K+.

Healthy male rats were exposed to a chronic ingesta of an isotonic NaCl solution during a period of four months. Two different preparations were utilized to study the effect of this treatment on the active mechanisms of Na+ reabsorption of kidney proximal tubular cells: outermost kidney cortex slices (rich in proximal tubules) and inside-out basolateral plasma membrane vesicles prepared from the same tissue. It was found that the activity of the ouabain-insensitive, Na-pump of basolateral plasma membranes of kidney proximal tubular cells was increased in about 70%, whereas the ouabain-sensitive, Na,K-pump activity did not change with the experimental treatment. These results represent a strong support to the two Na-pump's hypothesis since the treatment affected the Na-pump differentially without affecting the Na,K-pump.

The present work studied the turnover rate of (Na+ + K+)-ATPase as well as Mg2+- and Na+- ATPase activities in basolateral plasma membranes from kidney cortex cells of young and old rats. It was found that, as for the homogenates, the turnover rate of the (Na+ + K+)-ATPase was diminished by aging in about 40%. The Mg2+-ATPase activities on the other hand, were similar for the rat kidneys of young and old, in both the homogenates as well as the basolateral plasma membrane fractions.

The present paper characterizes the Na+-stimulated ATPase activity present in basal-lateral plasma membranes from guinea-pig kidney proximal tubular cells. These characteristics are compared with those of the (Na+ + K+)-stimulated ATPase activity, and they are: (A) Na+-ATPase activity: (1) requires Mg2+; (2) may be activated by mu molar quantities of Ca2+; (3) optimal ratio Mg:ATP = 5:1-2 and Ka for Mg:ATP = 3:0.60 mM; (4) Ka for Na+:8 mM; (5) does not require K+; (6) is only stimulated by Na+ and Li+ (in a lower extent); (7) is similarly stimulated by the Na+ salt of different anions; (8) hydrolyzes only ATP; (9) optimal temperature: 47 degrees C; (10) optimal pH: 6.9; (11) is ouabain insensitive; (12) is totally inhibited by 1.5 mM ethacrynic acid, 2 mM furosemide and 0.75 mM triflocin. (B) (Na+ + K+)-ATPase activity: (1) also requires Mg2+; (2) is inhibited by Ca2+; (3) optimal ratio Mg:ATP = 1.25:1 and Ka for Mg:ATP = 0.50: 0.40 mM; (4) Ka for Na+: 14 mM (data not shown); (5) needs K+ together with Na+; (6) K+ may be substituted by: Rb+ greater than NH+4 greater than Cs+; (7) is anion insensitive; (8) hydrolyzes mostly ATP and to a lesser extent GTP, ITP, UTP, ADP, CTP; (9) optimal temperature: 52 degrees C; (10) optimal pH: 7.2; (11) 100% inhibited by 1 mM ouabain; (12) 63% inhibited by 1.5 mM ethacrynic acid, 10% inhibited by 2 mM furosemide and insensitive to 0.75 mM triflocin.

Background: Sperm quality, including semen volume, sperm count, concentration, and total and progressive motility (collectively, "semen parameters"), has declined in the recent decades. Computer-assisted sperm analysis (CASA) provides sperm kinematic parameters, and the temporal trends of which remain unclear. Our objective is to examine the temporal trend of both semen parameters and kinematic parameters in Shanghai, China, in the recent years. Methods: This retrospective study analyzed semen parameters and kinematic parameters of 49,819 men attending our reproductive center by using CASA during 2015-2021. The total sample was divided into two groups: samples that surpassed the WHO guideline (2010) low reference limits ("above reference limit" group, ARL; n = 24,575) and samples that did not ("below reference limit" group, BRL; n = 24,614). One-way analysis of variance, Kruskal-Wallis test, independent samples t-test, and covariance analysis were used to assess the differences among groups. Year, age, and abstinence time were included in the multiple linear regression model of the ARL group to adjust the confounders and depict the trends in sperm quality. Results: Among all the total sample and the ARL and BRL groups, the age of subjects increased in recent years. Semen volume and sperm count showed declined tendency with years in the total sample, the ARL and BRL groups, and the subgroup of age or abstinence time, whereas sperm velocities showed increased tendency with years on the contrary. The multiple linear regression model of the ARL group, adjusting for age and abstinence time, confirmed these trends. Semen volume (β1= -0.162; CI: -0.172, -0.152), sperm count (β1= -9.97; CI: -10.813, -9.128), sperm concentration (β1 = -0.535; CI: -0.772, -0.299), motility (β1 = -1.751; CI: -1.830, -1.672), and progressive motility (β1 = -1.12; CI: -0.201, -0.145) decreased with year, whereas curvilinear line velocity (VCL) (β1 = 3.058; CI: 2.912, 3.203), straight line velocity (VSL) (β1 = 2.075; CI: 1.990, 2.161), and average path velocity (VAP) (β1 = 2.305; CI: 2.224, 2.386) increased over time (all p < 0.001). In addition, VCL, VSL, and VAP significantly declined with age and abstinence time. Conclusion: The semen parameters declined, whereas the kinematic parameters increased over the recent years. We propose that, although sperm count and motility declined over time, sperm motion velocity increased, suggesting a possible compensatory mechanism of male fertility. [ABSTRACT FROM AUTHOR]

The placenta plays an essential role in pregnancy, leading to proper fetal development and growth. As an organ with multiple physiological functions for both mother and fetus, it is a highly energetic and metabolically demanding tissue. Mitochondrial physiology plays a crucial role in the metabolism of this organ and thus any alteration leading to mitochondrial dysfunction has a severe outcome in the development of the fetus. Pregnancy-related pathological states with a mitochondrial dysfunction outcome include preeclampsia and gestational diabetes mellitus. In this review, we address the role of mitochondrial morphology, metabolism and physiology of the placenta during pregnancy, highlighting the roles of the cytotrophoblast and syncytiotrophoblast. We also describe the relationship between preeclampsia, gestational diabetes, gestational diabesity and pre-pregnancy maternal obesity with mitochondrial dysfunction., (© 2024 The Authors. The Journal of Physiology © 2024 The Physiological Society.)

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. [ABSTRACT FROM AUTHOR]

In oviparous marine fishes, the hyperosmotic induction of sperm motility in seawater (SW) is well established, however, the potential function of ion channels in the maintenance of post activated spermatozoon swimming performance remains largely unknown. Here, we investigated the influence of ion channels on the spermatozoon swimming parameters using the gilthead seabream (Sparus aurata) as a model for modern marine teleosts. Our data show that the SW-induced activation of seabream sperm motility requires three concomitant processes, the hyperosmotic shock, an ion-flux independent increase of the intracellular concentration of Ca2+ ([Ca2+]i), but not of [K+]i or [Na+]i, and the alkalization of the cytosol. The combination of all three processes is obligatory to trigger flagellar beating. However, the time-course monitoring of sperm motion kinetics and changes in the [Ca2+]i, [K+]i and [Na+]i in SW or in non-ionic activation media, showed that the post activated maintenance of spermatozoa motility is dependent on extracellular Ca2+ and K+. A meta-analysis of a seabream sperm transcriptome uncovered the expression of multiple ion channels, some of which were immunolocalized in the head and/or tail of the spermatozoon. Selective pharmacological inhibition of these ion channel families impaired the long-term motility, progressivity, and velocity of SW-activated spermatozoa. The data further revealed that some antagonists of K+-selective or Ca2+-selective channels, as well as of stretch-activated and mechanosensitive channels, altered the trajectory of spermatozoa, suggesting that these ion channels are likely involved in the control of the swimming pattern of the post activated spermatozoon. These combined findings provide new insight into the signaling pathways regulating spermatozoon activation and swimming performance in marine fishes. [ABSTRACT FROM AUTHOR]

Conflicting evidence exists regarding the effectiveness of magnesium supplementation during pregnancy in gestational diabetes mellitus (GDM) patients. This meta‐analysis examines the effect of magnesium on glycemic indices and metabolic status in GDM. We searched databases for randomized controlled trials (RCTs) conducted, and after applying inclusion and exclusion criteria, a total of four RCTs were considered eligible for the analysis. Outcome parameters included markers for glycemic control and metabolic status. A total of four RCTs with 198 participants (control = 99; magnesium supplemented = 99) were selected for the analysis. Magnesium supplementation resulted in a significant reduction in markers of glycemic control—fasting plasma glucose (standard mean difference (μ^) = −0.83; 95% CI: [−1.13, –0.54]; p‐value <.0001), and insulin levels (μ^ = −0.95; 95% CI: [−1.38, −0.52]; p‐value <.0001). Also, Mg intake resulted in altered oxidative stress markers TAC (μ^ = 1.09; 95% CI: [0.10, 2.07]; p‐value =.03) of the pregnant women. No significant effect on GSH and CRP levels was observed. This study provides evidence of the positive effects of magnesium intervention on insulin sensitivity and oxidative stress in GDM patients. [ABSTRACT FROM AUTHOR]

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 Ca2+- 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 Ca2+- 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 Ca2+- and Na+, K+-ATPases; however, expression of both ATPases was unaffected. Conclusion: Our findings suggest that the reduction of Ca2+- 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. [ABSTRACT FROM AUTHOR]

Alkalinization of sperm cytosol is essential for plasma membrane hyperpolarization, hyperactivation of motility, and acrosomal exocytosis during sperm capacitation in mammals. The plasma membrane of sperm cells contains different ion channels implicated in the increase of internal pH (pHi) by favoring either bicarbonate entrance or proton efflux. Bicarbonate transporters belong to the solute carrier families 4 (SLC4) and 26 (SLC26) and are currently grouped into Na+/HCO3− transporters and Cl−/HCO3− exchangers. Na+/HCO3− transporters are reported to be essential for the initial and fast entrance of HCO3− that triggers sperm capacitation, whereas Cl−/HCO3− exchangers are responsible for the sustained HCO3− entrance which orchestrates the sequence of changes associated with sperm capacitation. Proton efflux is required for the fast alkalinization of capacitated sperm cells and the activation of pH-dependent proteins; according to the species, this transport can be mediated by Na+/H+ exchangers (NHE) belonging to the SLC9 family and/or voltage-gated proton channels (HVCN1). Herein, we discuss the involvement of each of these channels in sperm capacitation and the acrosome reaction. [ABSTRACT FROM AUTHOR]

Human spermatozoan ion channels are specifically distributed in the spermatozoan membrane, contribute to sperm motility, and are associated with male reproductive abnormalities. Calcium, potassium, protons, sodium, and chloride are the main ions that are regulated across this membrane, and their intracellular concentrations are crucial for sperm motility. Fatty acids (FAs) affect sperm quality parameters, reproductive pathologies, male fertility, and regulate ion channel functions in other cells. However, to date the literature is insufficient to draw any conclusions regarding the effects of FAs on human spermatozoan ion channels. Here, we aimed to discern the possible effects of FAs on spermatozoan ion channels and direct guidance for future research. After investigating the effects of FAs on characteristics related to human spermatozoan motility, reproductive pathologies, and the modulation of similar ion channels in other cells by FAs, we extrapolated polyunsaturated FAs (PUFAs) to have the highest potency in modulating sperm ion channels to increase sperm motility. Of the PUFAs, the ω-3 unsaturated fatty acids have the greatest effect. We speculate that saturated and monounsaturated FAs will have little to no effect on sperm ion channel activity, though the possible effects could be opposite to those of the PUFAs, considering the differences between FA structure and behavior. [ABSTRACT FROM AUTHOR]

Calcium is one of the most important elements for intracellular signaling. Its role is so big and complex that we can distinguish various effects and biochemical cascades involving this ion into a separate signaling system–calcium signaling. This type of cell regulation mechanism is even more important for male gametes. The inability to perform transcription and the low level of translation are the reasons why post-translational processes, many of them being activated/inhibited by calcium or its target proteins, are the main way of regulation of cell function in mature sperm. Intracellular calcium level elevation is an essential step in the processes that precede fertilization, such as capacitation, hyperactivation, and acrosome reaction (AR). Ca2+ is required for progressive and hyperactivated motility; sperm cells incorporate this ion to prevent spontaneous acrosome reaction and to induce AR when the time comes. Huge difference in the impact of the same ion is achieved by the regulation complexity and specific localization of all signaling elements, which regulate Ca2+ influx and efflux, and its target proteins. Successful fertilization is impossible without proper functioning of the calcium signaling system in the male gamete. The achievements of the last decade, mediated by recent technical advances, have significantly improved our knowledge and understanding of the regulation mechanisms of sperm Ca2+ signals in various species, as well as the intracellular effects and spatial-temporal localization of these signals. In this review we have attempted to provide the most complete picture of mammalian sperm calcium signaling and to formulate the questions to be answered. [ABSTRACT FROM AUTHOR]

C11‐BODIPY581/591 is a fluorescent probe that has been successfully used to evaluate lipid peroxidation in different species, but it has not been completely studied in the dog. Thus, the aim of the present study was to assess lipid peroxidation of dog spermatozoa using C11‐BODIPY581/591 and compare different positive controls of the technique. Twenty‐four ejaculates were collected from 8 adult male dogs. Routine seminal characteristics were evaluated in raw semen. Lipid peroxidation evaluation was performed as described in other species. Samples were divided in three aliquots, exposed to UV radiation, incubated with hydrogen peroxide or left without treatment (control). Lipid peroxidation was significantly greater only in UV‐exposed samples than in the control ones (91 ± 6% vs. 8.3 ± 3.5%, p ˂.01). In conclusion, C11‐BODIPY581/591 is useful to evaluate lipid peroxidation of dog spermatozoa and UV radiation is a good promoter of membrane oxidation, so irradiated samples can be used as a positive control of this technique. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The current study evaluates the effect of different Mg levels in low‐salinity (3 g/L) water on growth, survival, haemolymph osmolality, cationic composition in haemolymph, carapace and whole body of Pacific white shrimp, Litopenaeus vannamei. A low‐cost salt mixture (LCSM) comprised of Na, K, Ca and Mg concentrations of 298, 9, 17 and 39 mg/L, respectively, in a 1‐g/L solution was modified by decreasing the Mg level of LCSM to allow different Mg levels in the culture medium (100, 78, 55, 30, 17, 13 and 12 mg/L). Reconstituted sea salt (RSS) was used as the control treatment with Mg level of 129 mg/L. A 42‐day growth trial (initial weight: 0.11 ± 0.01 g and stocking density: 20 shrimp/tank) was carried out in 150‐L plastic tanks, each equipped with a fluidized bed biofilter. As Mg2+ level was reduced, there was a subsequent reduction (p < 0.05) in shrimp performance reflected in final weight, weight gain, haemolymph osmolality, osmoregulatory capacity, Mg2+ concentration in haemolymph, carapace and whole body of shrimp paralleled by an increase in feed conversion ratio (FCR). Low haemolymph osmolality and Mg2+ concentrations (p < 0.05) in shrimp haemolymph were found to be indicative of stress, which was ultimately reflected as reduced growth and increased FCR in low Mg2+ concentrations at 3 g/L salinity. [ABSTRACT FROM AUTHOR]