Understanding Bidirectional Water Transport across Bronchial Epithelial Cell Monolayers: A Microfluidic Approach.

Deciphering the dynamics of water transport across bronchial epithelial cell monolayers is pivotal for unraveling respiratory physiology and pathology. In this study, we employ an advanced microfluidic system to explore bidirectional water transport across 16HBE14σ bronchial epithelial cells. Previous experiments unveiled electroneutral multiple ion transport, with chloride ions utilizing transcellular pathways and sodium ions navigating both paracellular and transcellular routes.

Special Issue "Advances in Artificial and Biological Membranes: Mechanisms of Ionic Sensitivity, Ion-Sensor Designs, and Applications for Ion Measurement".

Ion sensors, conventionally known as ion-selective membrane electrodes, were devised 100 years ago with the invention of a pH electrode with a glass membrane (in 1906 Cremer, in 1909 Haber and Klemensiewicz) [...

Precipitation of Inorganic Salts in Mitochondrial Matrix.

In the mitochondrial matrix there are insoluble, osmotically inactive complexes that maintain constant pH and calcium concentration. In the present paper we examine the properties of insoluble calcium and magnesium salts, namely phosphates, carbonates and polyphosphates which might play this role. We find that non-stoichiometric, magnesium-rich carbonated apatite, with very low crystallinity, precipitates in the matrix under physiological conditions.

Measurement of Multi Ion Transport through Human Bronchial Epithelial Cell Line Provides an Insight into the Mechanism of Defective Water Transport in Cystic Fibrosis.

We measured concentration changes of sodium, potassium, chloride ions, pH and the transepithelial potential difference by means of ion-selective electrodes, which were placed on both sides of a human bronchial epithelial 16HBE14σ cell line grown on a porous support in the presence of ion channel blockers. We found that, in the isosmotic transepithelial concentration gradient of either sodium or chloride ions, there is an electroneutral transport of the isosmotic solution of sodium chloride in both directions across the cell monolayer. The transepithelial potential difference is below 3 mV.

New ISE-Based Apparatus for Na, K, Cl, pH and Transepithelial Potential Difference Real-Time Simultaneous Measurements of Ion Transport across Epithelial Cells Monolayer⁻Advantages and Pitfalls.

Cystic Fibrosis (CF) is the most common fatal human genetic disease, which is caused by a defect in an anion channel protein (CFTR) that affects ion and water transport across the epithelium. We devised an apparatus to enable the measurement of concentration changes of sodium, potassium, chloride, pH, and transepithelial potential difference by means of ion-selective electrodes that were placed on both sides of a 16HBE14σ human bronchial epithelial cell line that was grown on a porous support. Using flat miniaturized ISE electrodes allows for reducing the medium volume adjacent to cells to approximately 20 μL and detecting changes in ion concentrations that are caused by transport through the cell layer.

Calcium phosphate buffer formed in the mitochondrial matrix during preconditioning supports ΔpH formation and ischemic ATP production and prolongs cell survival -A hypothesis.

Ischemic preconditioning makes cells less sensitive to oxygen deprivation. A similar effect can be achieved by increasing the calcium concentration and applying potassium channel openers. A hypothetical mechanism of preconditioning is presented.

Hydrocortisone inhibition of wild-type and αD200Q nicotinic acetylcholine receptors.

Short-term treatment with large doses of corticosteroids can result in acute weakness of muscles in processes that have not yet been fully characterized. Corticosteroids have been shown to exert direct inhibitory action on the muscle-type nicotinic acetylcholine receptor (AChR), and therefore can promote pharmacological muscle denervation. The mechanism of hydrocortisone (HC) blockage of AChR has not been fully established yet.

Multi-electrode system for measurement of transmembrane ion-fluxes through living epithelial cells.

Cystic Fibrosis (CF) is the most common fatal human genetic disease. It is caused by the defect in a single anion channel protein which affects ion and water transport across the epithelial tissue. A flat multi-electrode platform of diameter 12mm, allowing for measurement of four ions: sodium, potassium, hydrogen and chloride by exchangeable/replaceable ion-selective electrodes is described.

Measurement of ion fluxes across epithelia.

Epithelial tissues line all wet surfaces of vertebrate bodies. Their major function is directional transport of ions and water. Cells forming an epithelial layer are bound together by a tight junction that forms a barrier to ion flux.

[What we don't know about mitochondrial potassium channels?].

In the current work the authors present the most interesting, yet not fully understood issues regarding origin, function and pharmacology of the mitochondrial potassium channels. There are eight potassium channels known to contribute to the potassium permeability of the inner mitochondrial membrane: ATP-regulated channel, calcium-regulated channels of large, intermediate and small conductance, voltage-regulated Kv1.3 and Kv7.

Restoration of the response of the middle cerebral artery of the rat to acidosis in hyposmotic hyponatremia by the opener of large-conductance calcium sensitive potassium channels (BK).

Hyposmotic hyponatremia (the decrease of extracellular concentration of sodium ions from 145 to 121 mM and the decrease of hyposmolality from 300 to 250 mOsm/kg HO) impairs response of the middle cerebral artery (MCA) to acetylcholine and NO donor (S-nitroso-N-acetyl-DL-penicillamine). Since acidosis activates a similar intracellular signaling pathway, the present study was designed to verify the hypothesis that the response of the MCA to acidosis is impaired during acute hyposmotic hyponatremia due to abnormal NO-related signal transduction in vascular smooth muscle cells. Studies performed on isolated, cannulated, and pressurized rat MCA revealed that hyposmotic hyponatremia impaired the response of the MCA to acidosis and this was associated with hyposmolality rather than with decreased sodium ion concentration.

Multielectrode bisensor system for time-resolved monitoring of ion transport across an epithelial cell layer.

An ion-selective multielectrode bisensor system is designed to ensure reliable real-time concentration measurements of sodium, potassium, chloride, and pH in a small volume of biological liquid bathing a living human bronchial epithelial cell monolayer. The bisensor system allows the monitoring of major ions, which are simultaneously transported through the epithelia in both directions.

Ion transporting proteins of human bronchial epithelium.

The electrolyte transport system across human airway epithelium followed by water movement is essential for the normal mucociliary clearance that allows the maintenance of the aseptic condition of the respiratory tract. The function of epithelial cells is to control and regulate ionic composition and volume of fluids in the airways. Various types of proteins taking part in assuring effective ions and water transport in apical and basolateral membranes of the airway epithelium have been found (e.

Identification of a voltage-gated potassium channel in gerbil hippocampal mitochondria.

Transient cerebral ischemia is known to induce endogenous mechanisms that can prevent or delay neuronal injury, such as the activation of mitochondrial potassium channels. However, the molecular mechanism of this effect remains unclear. In this study, the single-channel activity was measured using the patch-clamp technique of the mitoplasts isolated from gerbil hippocampus.

Effect of selected NAD+ analogues on mitochondria activity and proliferation of endothelial EA.hy926 cells.

The aim of the study was to examine the effect of 1-methylnicotinamide (MNA) and 1-methyl-3-nitropyridine (MNP) on mitochondria activity and proliferation of endothelial EA.hy926 cells. The activity of MNA was also referred to nicotinamide (NAM) being MNA metabolic precursor.

Pharmacology of mitochondrial potassium channels: dark side of the field.

Mitochondrial potassium channels play an important role in cytoprotection. Potassium channels in the inner mitochondrial membrane are modulated by inhibitors and activators (potassium channel openers) previously described for plasma membrane potassium channels. The majority of mitochondrial potassium channel modulators exhibit a broad spectrum of off-target effects.

The H-loop in the second nucleotide-binding domain of the cystic fibrosis transmembrane conductance regulator is required for efficient chloride channel closing.

The cystic fibrosis transmembrane conductance regulator (CFTR) is an ATP-binding cassette (ABC) transporter that functions as a cAMP-activated chloride channel. The recent model of CFTR gating predicts that the ATP binding to both nucleotide-binding domains (NBD1 and NBD2) of CFTR is required for the opening of the channel, while the ATP hydrolysis at NBD2 induces subsequent channel closing. In most ABC proteins, efficient hydrolysis of ATP requires the presence of the invariant histidine residue within the H-loop located in the C-terminal part of the NBD.

Single channel studies of the ATP-regulated potassium channel in brain mitochondria.

Mitochondrial potassium channels in the brain have been suggested to have an important role in neuroprotection. The single channel activity of mitochondrial potassium channels was measured after reconstitution of the purified inner membrane from rat brain mitochondria into a planar lipid bilayer. In addition to a large conductance potassium channel that was described previously, we identified a potassium channel that has a mean conductance of 219 +/- 15 pS.

Calcium ions regulate K⁺ uptake into brain mitochondria: the evidence for a novel potassium channel.

The mitochondrial response to changes of cytosolic calcium concentration has a strong impact on neuronal cell metabolism and viability. We observed that Ca(2+) additions to isolated rat brain mitochondria induced in potassium ion containing media a mitochondrial membrane potential depolarization and an accompanying increase of mitochondrial respiration. These Ca(2+) effects can be blocked by iberiotoxin and charybdotoxin, well known inhibitors of large conductance potassium channel (BK(Ca) channel).

Potassium currents in human myogenic cells from healthy and congenital myotonic dystrophy foetuses.

The whole-cell patch clamp technique was used to record potassium currents in in vitro differentiating myoblasts isolated from healthy and myotonic dystrophy type 1 (DM1) foetuses carrying 2000 CTG repeats. The fusion of the DM1 myoblasts was reduced in comparison to that of the control cells. The dystrophic muscle cells expressed less voltage-activated K(+) (delayed rectifier and non-inactivating delayed rectifier) and inward rectifier channels than the age-matched control cells.

Large-conductance K+ channel opener CGS7184 as a regulator of endothelial cell function.

Large-conductance Ca(2+)-activated potassium (BK(Ca)) channels are present in endothelium, but their regulatory role remains uncharacterized. The aim of the present study was to investigate the pharmacological effects of the BK(Ca) channel opener ethyl-1-[[(4-chlorophenyl)amino]oxo]-2-hydroxy-6-trifluoromethyl-1H-indole-3-carboxylate (CGS7184) on endothelium in the aorta and coronary circulation, particularly with regard to nitric oxide (NO)-dependent regulation of vascular tone, as well as effects of CGS7184 on NO production, calcium homeostasis, and mitochondrial function in cultured endothelial cells. The vasorelaxant action of CGS7184 was studied in coronary circulation and in the aorta using isolated perfused guinea pig heart and rat aortic rings, respectively.

[Endothelial mitochondria--a novel target for pharmacology of endothelial dysfunction].

Vascular endothelium the inside layer of the cardiovascular system is presently looked upon as an important paracrine, autocrine and endocrine organ that determines the health of the cardiovascular system. In fact, healthy endothelium is essential for homeostasis of cardiovascular system, while endothelial dyfunction leads to cardiovascular diseases including atherosclerosis, diabetes and heart failure. Endothelial dysfunction is tightly linked to the overproduction of reactive oxygen species, development of oxidant stress and inflammatory response of endothelium.

New properties of mitochondrial ATP-regulated potassium channels.

The ATP-regulated potassium channel is present in the inner membrane of heart mitochondria. In this study, the activity of a single channel was measured after reconstituting the myocardium inner mitochondrial membrane into a planar lipid bilayer. We provide direct evidence of vectorial pH regulation of mitoK(ATP) channels.

A novel potassium channel in skeletal muscle mitochondria.

In this work we provide evidence for the potential presence of a potassium channel in skeletal muscle mitochondria. In isolated rat skeletal muscle mitochondria, Ca(2+) was able to depolarize the mitochondrial inner membrane and stimulate respiration in a strictly potassium-dependent manner. These potassium-specific effects of Ca(2+) were completely abolished by 200 nM charybdotoxin or 50 nM iberiotoxin, which are well-known inhibitors of large conductance, calcium-activated potassium channels (BK(Ca) channel).

Stilbene derivatives inhibit the activity of the inner mitochondrial membrane chloride channels.

Ion channels selective for chloride ions are present in all biological membranes, where they regulate the cell volume or membrane potential. Various chloride channels from mitochondrial membranes have been described in recent years. The aim of our study was to characterize the effect of stilbene derivatives on single-chloride channel activity in the inner mitochondrial membrane.