The balance of K+, Na+, and Cl– fluxes across the cell membrane with the Na+/K+ pump, ion channels, and Na+K+2Cl– (NKCC) and Na+–Cl– (NC) cotransport was calculated to determine the mech anism of cell shrinkage in apoptosis. It is shown that all unidirectional K+, Na+, and Cl– fluxes; the ion chan nel permeability; and the membrane potential can be found using the principle of the flux balance ...

Wild-type and mutants with alpha-subunits truncated at the N terminus of Na+/K+ pumps of Torpedo electroplax were expressed in Xenopus oocytes by injection of cRNAs encoding for one of the alpha-subunits and for the beta-subunit. Currents generated by the pump were investigated under voltage clamp in Na(+)-free solution, a condition where stimulation by external [K+] is the only voltage-depende...

Scenedesmus cells grown on high CO(2), when adapted to air levels of CO(2) for 4 to 6 hours in the light, formed two concentrating processes for dissolved inorganic carbon: one for utilizing CO(2) from medium of pH 5 to 8 and one for bicarbonate accumulation from medium of pH 7 to 11. Similar results were obtained with assays by photosynthetic O(2) evolution or by accumulation of dissolved inor...

Dense slurry flow through centrifugal pump casing has been modeled using the Eulerian-Eulerian approach with Eulerian multiphase model in FLUENT 6.1. First order upwinding is considered for the discretization of momentum, k and ε terms. SIMPLE algorithm has been applied for dealing with pressurevelocity coupling. A mixture property based k-ε turbulence model has been used for modeling turbulenc...

In vitro, cerebellar Purkinje cells can intrinsically fire action potentials in a repeating trimodal or bimodal pattern. The trimodal pattern consists of tonic spiking, bursting, and quiescence. The bimodal pattern consists of tonic spiking and quiescence. It is unclear how these firing patterns are generated and what determines which firing pattern is selected. We have constructed a realistic ...

Osmotic swelling is a common feature of many cataracts. Sugar cataracts and hereditary mouse cataracts are two types in which osmotic changes play a prominent role. In sugar cataracts, the initial swelling brought about by polyol accumuation leads to an imbalance in the pump-leak equilibrium. The pump mechanism becomes unable to keep pace with the leaky membranes. The marked increases in Na and...

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 cel...

In a pump-probe experiment, we have been able to control, with phase-locked probe pulses, the ultrafast nonlinear optical emission of a semiconductor microcavity, arising from polariton parametric amplification. This evidences the coherence of the polariton population near k=0, even for delays much longer than the pulse width. The control of a large population at k=0 is possible although the pr...

We studied the role of the sodium-potassium pump in erythrocytes of 12 patients with sickle cell anemia (SS). Ouabain-binding sites per cell and pump-mediated Rb/K uptake were significantly higher in SS patients than in white or black controls. Ouabainresistant Rb/K influx was also greater than in normal controls or patients with sickle cell trait. Deoxygenation of SS erythrocytes increased oua...

PHYSIOLOGISTS GENERALLY ACCEPT the H -K -ATPase as the principal gastric proton pump, and a mechanism of membrane recruitment and recycling of the pump as the primary means for regulating the activity of gastric HCl secretion. One of the major challenges in gastric HCl secretory physiology is the identification and characterization of the K efflux pathway across the apical membrane that must ac...