In an attempt to recreate the microenvironment necessary for directed hematopoietic stem cell differentiation, control over the amount of ions available to the cells is necessary. The release of potassium ion and calcium ion via the control of cross-linking density of a poly(2-hydroxyethyl methacrylate) (pHEMA)-based hydrogel containing 1 mol % 2-methacryloyloxyethyl phosphorylcholine (MPC) and...

An enzymatic system in cell membranes actively transports sodium ions outward and potassium ions inward. Like other enzyme systems this one has a st,oichiometry and presumably, a reaction sequence and active sites. Knowledge of the latter feat,ures is fragmentary. Isolation of a reaction intermediate would clarify the reaction sequence and could lead to chemical characterization of an active si...

Long-term potentiation (LTP) is a form of activity-dependent plasticity that occurs during learning. Potassium channels are the most diverse group of all ion channels that related to synaptic plasticity. Small-conductance calcium-activated potassium channels (SKs) are found in hippocampal CA1 neurons and by inhibiting of postsynaptic potentials are involved in synaptic transmission impairment. ...

Some neuronal receptors perceive external input in the form of hybrid periodic signals. The signal detection may be based on the mechanism of vibrational resonance, in which a system's response to the low frequency signal can become optimal by an appropriate choice of the vibration amplitude of HFS. The vibrational resonance effect is investigated in a neuron model in which the intra- and extra...

While studying the factors affecting the absorption of mineral elements by plants, the writer showed that the hydrogen-ion concentration of the medium affects the absorption of potassium and phosphorus by wheat seedlings grown in water cultures. (4) ^ More phosphorus was absorbed from potassium phosphate solutions with initial pH values of 5.0 and below than from those with pH values of 6.0 and...

Quaternary ammonium ions were applied to the inside of single myelinated nerve fibers by diffusion from a cut end. The resulting block of potassium channels in the node of Ranvier was studied under voltage-clamp conditions. The results agree in almost all respects with similar studies by Armstrong of squid giant axons. With tetraethylammonium ion (TEA), pentyltriethylammonium ion (C(5)), or non...

Potassium ion channels form pores in cell membranes, allowing potassium ions through while preventing the passage of sodium ions. Despite numerous high-resolution structures, it is not yet possible to relate their structure to their single molecule function other than at a qualitative level. Over the past decade, there has been a concerted effort using molecular dynamics to capture the thermody...

Rice (Oryza sativa) is sensitive to salinity, which affects one-fifth of irrigated land worldwide. Reducing sodium and chloride uptake into rice while maintaining potassium uptake are characteristics that would aid growth under saline conditions. We describe genetic determinants of the net quantity of ions transported to the shoot, clearly distinguishing between quantitative trait loci (QTL) fo...

The high rate of ion flux and selectivity of potassium channels has been attributed to the conformation and dynamics of the ions in the filter which connects the channel cavity and the extracellular environment. The cavity serves as the reservoir for potassium ions diffusing from the intracellular medium. The cavity is believed to decrease the dielectric barrier for the ions to enter the filter...

Voltage-sensitive potassium ion channels are essential for life, but the molecular basis of their ion conduction is not well understood. In particular, the impact of ion concentration on ion conduction has not been fully studied. We performed several micro-second molecular dynamics simulations of the pore domain of the Kv1.2 potassium channel in KCl solution at four different ion concentrations...