Renal Disease; Fluid and Electrolyte Disorders
John S. Axford, Chris A. O'Callaghan in Medicine for Finals and Beyond, 2023
Unlike many ions and molecules, water cannot be pumped directly in the body. Instead, water moves between sites by osmosis if there is an osmotic gradient and if the barrier separating the two sites contains pores or channels through which it can pass. Aquaporin molecules form water channels in most cell membranes. Intra- and extracellular fluid compartments are normally in approximate osmotic equilibrium. The Na+/K+ATPase pumps sodium out of cells and potassium into cells so: Intracellular fluid has high potassium and low sodium concentrations.Extracellular fluid has low potassium and high sodium concentrations.
The Electrical Properties of Cells
Richard C. Niemtzow in Transmembrane Potentials and Characteristics of Immune and Tumor Cell, 2020
One of the proteins in the membrane of animal cells is the (Na,K)-ATPase. This protein translocates Na+ ions from the intracellular surface of the membrane to the exterior surface, at the same time moving K+ ions from exterior to interior.3 This process requires the utilization of one ATP molecule per translocation. The protein has such a large affinity for intracellular Na+ that, under normal conditions, for every Na+ ion which leaks into the cell from the outside, one Na+ is moved by the ATPase outward. The net effect of this activity is to keep the intracellular Na+ concentration very low and to make the net movement of Na+ across the membrane zero; i.e., Na+appears to be impermeable and can counterbalance the effect of the impermeant intracellular anions.
Endogenous Digitalis-Like Factors: Past Progress and Future Prospects
Antonio Coca, Ricardo P. Garay in Ionic Transport in Hypertension: New Perspectives, 2019
Hamlyn et al.74 were the first to directly measure elevated circulating levels of a Na,K-ATPase inhibitor in essential hypertensives. While the level of activity that they measured correlated with erythrocyte intracellular sodium content, no relationship with plasma digoxin-like activity was apparent. This seeming failure to support a role for endogenous digoxin in hypertension should be assessed in light of the fact that subsequent work from Hamlyn et al.58 found correlations between digoxin immunoactivity in plasma and aldosterone (an inverse relationship) or catecholamines (a positive relationship) that are consistent with a natriuretic hormone that also has the ability to activate the sympathetic nervous system. A potential explanation for the reported discrepancy is that their radioimmunoassay may have detected biologically active and inactive forms of the same substance. Subsequent work from other laboratories (discussed below) provides evidence that Na,K-ATPase inhibitory activity and digoxin-like immunoactivity in blood can correlate and be related to blood pressure and urinary sodium excretion.
The effects of titanium nanoparticles on enzymatic and non-enzymatic biomarkers in female Wistar rats
Published in Drug and Chemical Toxicology, 2022
Esin Gülnaz Canli, Cebrail Gumus, Mustafa Canli, Hasan Basri Ila
Na,K-ATPase is a membrane-bound enzyme that transports Na and K ions across the biological membranes in vertebrates, transporting 3 Na ions out of the cell and 2 K ions into the cell. Mg-ATPase is found in the cytoplasm and in the mitochondria and regulates the Mg ion concentration in the cell and used in oxidative phosphorylation in the mitochondria. Both Na,K-ATPase, and Mg-ATPase use requires too much ATP energy to carry out their duties (Howarth et al.2012). They were also shown to be sensitive to environmental pollutants (Guo et al.2013, Singh et al.2013, Canli and Canli 2017, 2019). Studies carried out with mammals showed that oral administration of NPs was found to cause alterations in ATPase activities (Canli et al.2017, 2019a). AChE is an important component of the nerve system, functioning in impulse signaling. It's basic duty is to break down the neurotransmitter called acetylcholine into acetate and choline. Environmental xenobiotic substances including NPs were found to alter the activity of AChE which leads it to be used as a diagnostic tool to detect the effects of xenobiotic in animals (Durmaz et al.2006, Piner and Uner 2012, Silva-Herdade and Saldanha 2013, Yilmaz et al.2015, 2017). Our previous study also showed that aluminum NPs administered orally caused significant decreases in AChE activity in the brain of rats (Canli et al.2019a).
Glycoprotein levels and oxidative lung injury in experimental diabetes: effect of oxovanadium(IV) complex based on thiosemicarbazone
Published in Toxicology Mechanisms and Methods, 2021
Bertan Boran Bayrak, Sevim Tunali, Tulay Bal-Demirci, Bahri Ulkuseven, Refiye Yanardag
Na+/K+-ATPase is an integral membrane enzyme that is ubiquitously found in animal cells. It plays a crucial role in maintaining electrolyte balance in cells via exporting three Na+ ions and imports two K+ ions across the plasma membrane using the energy released during the hydrolysis of one ATP molecule to ADP and inorganic phosphate (Pi) (Kaločayová et al. 2015). The degree of peroxidation of lipid and/or protein molecules in cell membrane is associated with decrease in the Na+/K+-ATPase activity (de Lores Arnaiz and Ordieres 2014). According to our findings, Na+/K+-ATPase decreased in STZ-induced diabetic group. Decrease in Na+/K+-ATPase activity may be due to the redox-sensitive properties of Na+/K+-ATPase, which can be regulated by levels of intracellular ROS (Yan et al. 2016). Treatment with VOL to diabetic group statistically increased Na+/K+-ATPase activity.
Histological and biochemical investigation of the renoprotective effects of metformin in diabetic and prostate cancer model
Published in Toxicology Mechanisms and Methods, 2021
Pınar Koroglu-Aydın, Bertan Boran Bayrak, Ilknur Bugan, Omur Karabulut-Bulan, Refiye Yanardag
MPO is a heme peroxidase expressed in neutrophils and monocytes. It is released by activated leukocytes and some tissue macrophages during inflammation (Davies and Hawkins, 2020). It is suggested that measurement of MPO activity under inflammatory conditions gives more sensitive results than histopathological examination of tissue (Faith et al. 2008). In addition, increased MPO activity is one of the best biochemical markers for diagnoses of diseases such as diabetes, cancer, chronic liver and kidney diseases (Khan et al. 2018). Na+/K+-ATPase is an integral membrane enzyme that is ubiquitously found in animals cells. It plays a crucial role in maintaining cells electrolyte balance. It is responsible for ion pumping functions such as exporting three Na+ ions and imports two K+ ions across the plasma membrane using the energy released during the hydrolysis of one ATP molecule to ADP and inorganic phosphate (Pi) (Kaločayová et al. 2015). In the current study, not only remarkable increase in MPO activities, but also a notable decrease in Na+/K+-ATPase activities of diabetic, cancer and DC animals was obsreved in comparison to control rats. Imbalance between oxidant and antioxidant status caused by overproduction of ROS may lead to escalation of MPO activity. In addition, exposure of kidney tissue to oxygen-derived free radicals may have caused a decrease in ATPase activity due to redox sensitivity (Srikanthan et al. 2016).
Related Knowledge Centers
- Adenosine
- Animal
- Atpase
- Enzyme
- Potassium
- Sodium
- Transmembrane Protein
- Triphosphatase
- Electroreception & Electrogenesis
- Membrane