The human H(+)-K(+)-ATPase, ATP1AL1, belongs to the subgroup of nongastric, K(+)-transporting ATPases. In concert with the structurally related gastric H(+)-K(+)-ATPase, it plays a major role in K(+) reabsorption in various tissues, including colon and kidney. Physiological and immunocytochemical data suggest that the functional heteromeric ion pumps are usually found in the apical plasma membr...

437 C o m m e n t a r y In this issue of the JGP, Vedovato and Gadsby show us that the native Na/K pumps of Xenopus laevis oocytes are even more complex machines than we realized. Readers of the JGP will be aware that Na/K pumps extrude three Na ions and import two K ions into cells with each pump cycle at the expense of one ATP being hydrolyzed to ADP. It now turns out that Na/K pumps develop ...

beta-Agonists cause an inhibition of contractility and a transient stimulation of Na+/K+ pumping in smooth muscle cells of the stomach from the toad Bufo marinus. To determine if the stimulation of Na+/K+ pumping causes changes in intracellular [Na+] ([Na+]i) that might link Na+ pump stimulation to decrease Ca2+ availability for contraction, [Na+]i was measured in these cells with SBFI, a Na(+)...

We examined the dependence of peak Na+ pump and Na+/Ca2+exchanger currents on prior Na+pump inhibition induced by exposure to zero extracellular K+ in voltage-clamped adult murine ventricular myocytes. Abrupt activation of the Na+ pump by reexposure of myocytes to extracellular K+ with a rapid solution switcher resulted in the development of a transient peak current at ∼500 ms, followed by a de...

THE MAINTENANCE OF MAMMALIAN cell volume fundamentally rests on net cation extrusion through Na -K -activated ATPase, the Na pump. The publication by Shahidullah et al. (11) persuasively identifies the series of events by which a widely used inhibitor of anion transport, DIDS, can reduce Na pump activity of porcine nonpigmented ciliary epithelial (NPE) cells. DIDS sequentially acidifies the NPE...

1. Sodium was injected into an identified snail neurone by passing current between two intracellular micro-electrodes, the membrane potential being recorded with a third micro-electrode.2. The injection of about 25 p-equiv Na, but not the injection of similar quantities of K or Li, caused a hyperpolarization of up to 20 mV. This response to Na injection was blocked by application of ouabain or ...

We have found a defect in the ouabain-sensitive Na+, K+-ATPase (Na+ pump, EC 3.6.1.37) of erythrocytes from streptozocin diabetic rats. This defect was accompanied by an increase in cell volume and osmotic fragility and a decrease in the cytosolic K+/Na+ ratio. There was also a doubling in the time needed for diabetic erythrocytes to pass through 4.7-micron channels in a polycarbonate filter. O...

The skeletal muscle sodium pump plays a major role in the removal of K(+) ions from the circulation postprandial, or after a physical activity bout, thereby preventing the development of hyperkalemia and fatigue. Insulin and muscle contractions stimulate Na(+)-K(+)-ATPase activity in skeletal muscle, at least partially via translocation of sodium pump units to the plasma membrane from intracell...

Disinhibition-induced bursting activity in cultures of fetal rat spinal cord is mainly controlled by intrinsic spiking with subsequent recurrent excitation of the network through glutamate synaptic transmission, and by autoregulation of neuronal excitability. Here we investigated the contribution of the electrogenic Na/K pump to the autoregulation of excitability using extracellular recordings ...