Healthy cerebrovascular myocytes express members of several different ion channel families which regulate resting membrane potential, vascular diameter, and vascular tone and are involved in cerebral autoregulation. In animal models, in response to subarachnoid blood, a dynamic transition of ion channel expression and function is initiated, with acute and long-term effects differing from each o...

We present molecular dynamics simulations of a multicomponent, asymmetric bilayer in mixed aqueous solutions of sodium and potassium chloride. Because of the geometry of the system, there are two aqueous solution regions in our simulations: one mimics the intracellular region, and one mimics the extracellular region. Ion-specific effects are evident at the membrane/aqueous solution interface. N...

It has been hypothesized that transmembrane allostery is the basis for inactivation of the potassium channel KcsA: opening the intracellular gate is spontaneously followed by ion expulsion at the extracellular selectivity filter. This suggests a corollary: following ion expulsion at neutral pH, a spontaneous global conformation change of the transmembrane helices, similar to the motion involved...

Membrane transport may be effected by specific enzymatic systems. In a search for an enzymatic basis for sodium transport, Skou discovered an adenosine triphosphatase activity in particles from crab nerve which required both sodium and potassium ions together (1, 2). A similar activity was later identified in broken erythrocyte membranes as a part of the active transport system for sodium and p...

Potassium is the most abundant metal ion in every living cell. This ion is essential due to its requirement for the activity of the ribosome and many enzymes but also because of its role in buffering the negative charge of nucleic acids. As the external concentrations of potassium are usually low, efficient uptake and intracellular enrichment of the ion is necessary. The Gram-positive bacterium...

using the evaporating method, the solubility of potassium nitrate was determined in various mixtures containing water and ethanol at 25°c. the results show that the solubility of kno3 decreases with increasing the mass percent of ethanol in the mixtures. this trend is along with decreasing the dielectric constant of water+ethanol mixtures. moreover, it can be concluded that the totqal solubilit...

Open-tip microelectrodes containing a potassium-sensitive liquid ion exchanger (Corning 477317) were used to study the effects of ouabain on the intracellular potassium activity and the transmembrane potentials of beating canine cardiac Purkinje fibers. The preparations were superfused with Tyrode's solution containing ouabain, 2 X 10(-7) M, and potassium, 4 mM, for 30 minutes. At the end of th...

BACKGROUND Atrial fibrillation (AF) arises from abnormalities in atrial structure and electrical activity. Microelectrode arrays (MEA) is a real-time, nondestructive measurement of the resting and action potential signal, from myocardial cells, to the peripheral circuit of electrophysiological activity. This study examined the field action potential duration (fAPD) of the right atrial appendage...

~Clay materials separated from estuarine sediments in Louisiana exhibit a selectivity for exchangeable calcium in laboratory experiments. The studies were conducted at 25~ and 60~ in mixed calcium and potassium chloride solutions in which the equivalent fraction of potassium varied from 0.12 to 0.54. Calcium selectivity was observed to increase with an increase in the equivalent fraction of pot...