Search results for "Potassium"
showing 10 items of 930 documents
Intestinal transport in constipation and diarrhoea.
1988
Approximatively 10 liters of fluid enter the gastrointestinal tract with food and endogenous secretions, and only less than 100 ml or 1% leave it with the faeces. Minor changes of this equilibrium in the intestinal transport may cause diarrhoea or constipation. Functions of small and large intestine differ markedly in transport of electrolytes and water. The relatively leaky epithelium of the small intestine allows for rapid equilibrium of osmolality in both directions while the tight epithelium of the colon preserves electrolytes and water once they have been absorbed. It may compensate secretory diarrhoea of the small intestine for instance caused by bacterial toxins to a certain degree u…
Determination of Phenylephrine Hydrochloride by Flow Injection Analysis with Chemiluminescence Detection
2001
Abstract A new method is proposed for the determination of phenylephrine hydrochloride by flow injection analysis with direct chemiluminescence detection. The method is based on the oxidation of the drug by potassium permanganate in sulfuric acid medium at 80°C. The calibration graph is linear over the range 0.03–8 ppm phenylephrine hydrochloride, with a relative standard deviation (n = 51, 0.5 ppm) of 1.1% and sample throughput of 134/h. The influence of 38 different foreign compounds was tested, and the method was applied to the determination of phenylephrine hydrochloride in 8 different pharmaceutical formulations.
Die Wirkung von Ouabain auf die Elimination von Noradrenalin aus der Perfusionsfl�ssigkeit des isolierten Kaninchenherzens
1966
Isolated rabbit hearts were perfused with Tyrode solution containing 10 ng/ml (-)-noradrenaline for 20 min. The uptake by the heart of noradrenaline was calculated by estimating the percentage of amine removed from the perfusion fluid during a single passage through the heart. Previous experiments have shown that the amount of noradrenaline removed from the perfusion fluid corresponds well to the amount retained by the heart. In control experiments, the mean removal (elimination) of noradrenaline was 50±1.7% of the amount infused as measured biologically and 46±2.2% as measured fluorimetrically. Ouabain was added to the perfusion fluid at concentrations ranging from 2.74·10−7 to 2.0·10−6 mo…
Red blood cell sodium and potassium after hydrochlorothiazide.
1981
In six of seven healthy males 6 days of hydrochlorothiazide (HCT), 50 mg twice daily, without potassium supplements resulted in a rise in red blood cell (RBC) sodium concentration. Serum potassium concentration fell in all subjects. Four days after discontinuing HCT, intracellular sodium and extracellular potassium concentrations had normalized. Throughout the evaluation period the course of mean relative intracellular sodium was almost a mirror image of mean relative extracellular potassium. Thus, either the decline of serum potassium or of HCT (because of its inhibitory effect on Na-K-ATPase activity) might have diminished Na-K-ATPase–dependent active RBC sodium efflux with a resultant ri…
Effect of a "therapeutic" concentration of digitoxigenine on myocardial potassium and sodium content in Ca-poor media.
1972
The effect of 3·10−7 g/ml digitoxigenine on cellular K and Na concentrations, [K]i and [Na]i, water content, extracellular space, and contractile force was investigated in isolated electrically stimulated left guinea-pig auricles at reduced extracellular Ca concentration (0.45 mM). Digitoxigenine, which increased contractile force without producing arrhythmias or contractures, decreased [K]i and enhanced [Na]i. Water content and extracellular space remained unchanged. It is concluded that digitoxigenine can decrease myocardial [K]i and increase [Na]i even in “therapeutic” concentrations, provided that the experiments are performed in Ca-poor media.
Der Einflu� von Monojodessigs�ure auf das Aktionspotential des Rattenzwerchfells
1959
1. The action of iodoacetic acid (IA) was studied on the isolated rat diaphragm at 20–22° C. Membrane and action potentials were led off with intracellular microelectrodes. 2. IA causes a contracture which is complete in 4 hours. As long as t he contracture develops, the membrane potential remains constant. A contracture identical with that seen in a normal preparation can be produced by IA in the presence of isotonic K2SO4. 3. The amplitude of the action potential is only slightly reduced during the first two hours after addition of IA. The duration of the action potential is significantly increased. Finally, action potentials with a plateau are obtained which resemble those of normal vent…
Tonic inhibitory action by nitric oxide on spontaneous mechanical activity in rat proximal colon: involvement of cyclic GMP and apamin-sensitive K+ c…
1999
The cellular mechanisms by which endogenous nitric oxide (NO) modulates spontaneous motility were investigated in rat isolated proximal colon. The mechanical activity was detected as changes in intraluminal pressure. Apamin (1–100 nM) produced a concentration-dependent increase in the amplitude of the spontaneous pressure waves. The maximal contractile effect was of the same degree as that produced by Nω-nitro-L-arginine methyl ester (L-NAME) (100 μM) and the joint application of apamin plus L-NAME had no additive effects. Apamin (0.1 μM) reduced the inhibitory effects (i.e. reduction in the amplitude of the pressure waves) induced by sodium nitroprusside (SNP) (1 nM–10 μM) or 8-Br-cyclic G…
Effects of Quinine and Quinidine on the Transient Outward and on the L-Type Ca<sup>2+</sup> Current in Rat Ventricular Cardiomyocytes
2002
The effects of the enantiomers quinine and quinidine on the transient outward current (I<sub>to</sub>) and on the L-type Ca<sup>2+</sup> current (I<sub>Ca</sub>) were investigated in rat ventricular cardiomyocytes using the patch-clamp technique. At a stimulation frequency of 2 Hz, both quinine and quinidine depressed the magnitude of I<sub>to</sub> and I<sub>Ca</sub>; the half-maximal effects on I<sub>to</sub> were achieved at 11 and 15 µmol/l, respectively, and those on I<sub>Ca</sub> at 14 and 10 µmol/l, respectively. At 0.2 Hz, both drugs depressed the magnitude of I<sub>to</sub>, but not tha…
Akute Trijodthyroninwirkungen auf den Kalium-Umsatz von Meerschweinchenvorh�fen
1963
Akute Wirkungen von Trijodthyronin (T3 10−6 und 10−5 g/ml) auf den K-Umsatz von Meerschweinchenvorhofen wurden mit Hilfe von 42K in vitro untersucht. Veranderungen der intracellularen Ionenkonzentrationen wurden nur nach 2 Std dauernder Einwirkung von T3 10−5 g/ml beobachtet. Zu diesem Zeitpunkt war die intracellulare K-Konzentration signifikant erhoht. T3 10−6 g/ml steigerte den K-Umsatz des Meerschweinchenvorhofs. K-Influx und -Efflux waren nach 2 Std Einwirkungsdauer in gleichem Ausmas gesteigert, die K-Permeabilitat war betrachtlich erhoht. Zu spateren Zeitpunkten nahmen K-Influx und -Efflux ab. T3 10−5 g/ml verminderte den K-Umsatz des Meerschweinchenvorhofs. Der K-Efflux war, vor alle…
Änderungen des Elektrolytgehaltes von Erythrozyten und Plasma bei nephrektomierten Ratten
1957
After two-stage nephrectomy in rats the potassium concentration in the red blood corpuscles (RBC) decreases from 10.6 ± 0.3 to 5.5 ± 0.3 mEq per 100 ml of RBC within 48 h. The decrease is accompanied by a much smaller increase in the plasma potassium concentration; the hyperkaliemia in nephrectomized rats is less pronounced than in nephrectomized dogs or anuric humans. Na+ in RBC increases by about 44% after nephrectomy; while there is only a very slight decrease of Na+ in plasma. Plasma chlorides drop from 10.92 ± 0.08 mEq/100 ml of plasma to 6.00 ± 0.81 mEq % within 48 h after nephrectomy. RBC chlorides tend to increase again after an initial drop from 5.22 ± 0.07 to 3.82 ± 0.90 mEq% with…