Search results for "Acellular"

�ber den Einflu� von Mangan-Ionen auf die positiv inotrope Wirkung von Adrenalin, Theophyllin und Digitoxigenin an isolierten Meerschweinchenvorh�fen

1969

The influence of bivalent manganese ions (Mn++) on the positive inotropic effect of adrenaline, theophylline, and digitoxigenin was studied in isolated, electrically driven left guinea-pig auricles in phosphate-free Tyrode's solutions with different extracellular calcium concentrations ([Ca]e; 0.45; 1.8; 7.2 mM).

�ber den Mechanismus der positiv inotropen Wirkung von Theophyllin am Warmbl�terherzen

1971

In order to further elucidate the mechanism of the positive inotropiceffect of theophylline (T) in mammalian cardiac muscle, the influence of T on contractile force, extracellular space,45Ca uptake,45Ca release, and total myocardial calcium concentration was investigated in isolated, electrically driven (frequency 170 beats/min) or quiescent left guinea-pig atria. The investigations were performed in Tyrode solution containing 0.45 mM CaCl2. T concentration was 5×10−4 g/ml. Under these conditions, T exerted maximal positive inotropic but no toxic effects, that is, it did not cause contractures or arrythmias within 60 min (Fig. 1). The experiments provide evidence that T increases the rate o…

Influence of intracellular sodium concentration on calcium influx in isolated guinea pig auricles.

1969

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…

Blood volume and extracellular space (ECS) of the whole body and some organs of the rat.

1978

Methods are described for estimation of blood volume and extracellular space (ECS) in the whole body and in some organs with 51Cr, 14C-thiocyanate and 3H-inulin. A mean blood volume of 47 ml/kg, a thiocyanate space of 350 ml/kg and a inulin space of 288 ml/kg were determined in the rat. The corresponding values of organs are shown in figures 1--3.

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…

Experiments on the metyrapone reducing microsomal enzyme system.

1970

The formation of reduced metyrapone [2-methyl-1.2-bis-(3-pyridyl)-1-propanol] from metyrapone [2-methyl-1.2-bis-(3-pyridyl)-1-propanone] in the liver has been studied. Reduced metyrapone appeared as the main metabolite of metyrapone in the isolated perfused rat liver. Experiments on the intracellular distribution of the metyrapone reducing activity revealed that metyrapone reductase is mainly localized in the microsomal fraction. In the 105,000 × g supernatant only a little activity was found.

Extracellular ATP Increases <i>L</i>-Carnitine Transport and Content in C2C12 Cells

2008

Extracellular ATP regulates cell proliferation, muscle contraction and myoblast differentiation. ATP present in the muscle interstitium can be released from contracting skeletal muscle cells. <i>L</i>-Carnitine is a key element in muscle cell metabolism, as it serves as a carrier for fatty acid through mitochondrial membranes, controlling oxidation and energy production. Treatment of C2C12 cells with 1 mmol/l of ATP induced a marked increase in <i>L</i>-carnitine uptake that was associated with an increase in <i>L</i>-carnitine content in these cells. These effects were found to be dependent on the density of the cultured cells and on the dose of ATP. The…

Effects of Kaempferol and Myricetin on Inducible Nitric Oxide Synthase Expression and Nitric Oxide Production in Rats

2010

Abstract:  When administered as drugs or consumed as food components, polyphenolic compounds synthesized in plants interfere with intracellular signal transduction pathways, including pathways of nitric oxide synthase expression. However, effects of these compounds in vivo do not always correlate with nitric oxide synthase-inhibiting activities revealed in experiments with cultured cells. The initial goal of this work was to compare effects of flavonoids kaempferol and myricetin on inducible nitric oxide synthase mRNA and protein expression monitored by real-time RT-PCR and immunohistochemistry and to evaluate the impact of these effects on nitric oxide production in rat organs measured by …