In order to understand the electrochemical behavior of a living cell at a low extracellular potassium concentration, a model is constructed. The model involves only the ATP driven sodium-potassium pump, and the sodium and potassium channels. Predictions of the model fit the N-shape of the current-voltage characteristic at low extracellular potassium. The model can, furthermore, quantitatively a...

Potassium-sensitive microelectrodes were used to measure the intracellular level of potassium in Calliphora salivary glands. During stimulation with 1 X 10(-8) M 5-HT, the potassium concentration increased from a resting level of 133.2 to 139.0 mM. When the external concentration of potassium was reduced below 2mM there was a rapid loss of potassium which could be partially reversed by 5-HT. Du...

The large-conductance, calcium-activated BK-α/β4 potassium channel, localized to the intercalated cells of the distal nephron, mediates potassium secretion during high-potassium, alkaline diets. Here we determine whether BK-α/β4-mediated potassium transport is dependent on epithelial sodium channel (ENaC)-mediated sodium reabsorption. We maximized sodium-potassium exchange in the distal nephron...

Rats fed a diet high in potassium for several days survive an acute load of potassium that is lethal to animals on a regular diet. Previous data suggested that this survival occurred because of enhanced kaluresis. Although increased urinary excretion may occur, the major mechanism of this potassium adaptation phenomenon has been found to be extrarenal. Despite nephrectomy just before study, rat...

BACKGROUND The purpose of this study was to compare the myocardial protective effect of histidine-tryptophan-potassium and glucose-insulin-potassium cardioplegic solutions in patients with a dilated heart (left ventricular diastolic diameter > 55 mm, left ventricular systolic diameter > 45 mm) associated with prolonged cross-clamp time (longer than 200 minutes). METHODS We selected 20 patient...

1. The role of water balance in the hypokalaemia of rats with diabetes insipidus (DI rats) was studied. 2. After a 3-day balance study DI rats had a lower muscle potassium content, and plasma [K+], and the urinary excretion of potassium in response to oral KCl loading was reduced when compared to normal rats. The hypokalaemia was found to be associated with elevated concentrations of potassium ...

Rhabdomyolysis and myoglobinuria occur commonly in men who sustain environmental heat injury during intensive physical training in hot climates. These also occur in patients with potassium depletion. Since physical training in hot climates may be accompanied by serious losses of body potassium, the possibility was considered that performance of strenuous exercise when potassium deficient might ...

AIMS Diuretic treatment is often needed in acute heart failure following myocardial infarction (MI) and carries a risk of abnormal potassium levels. We examined the relation between different levels of potassium and mortality. METHODS AND RESULTS From Danish national registries we identified 2596 patients treated with loop diuretics after their first MI episode where potassium measurement was...

The standard and most widely accepted method for the determination of potassium depends upon its precipit,ation as potassium chloroplatinate. The modification called the Lindo-Gladding procedure (1) is official with the Association of Official Agricultural Chemists. Methods based upon the precipitation of potassium as potassium of cobalti-nitrite (2), have been very useful in determination of p...

Isoproterenol stimulates cellular accumulation of cyclic adenosine 3':5'-monophosphate (cyclic AMP) and produces a 2- to 4-fold increase in bidirectional potassium fluxes in turkey erythrocytes. Ouabain, which does not alter catecholamine-stimulated cellular cyclic AMP, inhibits potassium influx by 50 to 70%, does not alter potassium outflux or isoproterenol-stimulated potassium influx, but inc...