Search results for "Potassium"
showing 10 items of 930 documents
4-Aminopyridine and barium chloride attenuate the anti-epileptic effect of carbamazepine in hippocampal slices
1991
The exact mode of action of the anti-epileptic agent carbamazepine is unknown. In hippocampal slices in which epileptiform discharges were induced by addition of penicillin to the perfusion medium, the depressant effect of carbamazepine was attenuated by the potassium-channel blockers barium chloride (0.1 mM) and 4-aminopyridine (200 microM), which suggested that potassium fluxes might be involved in the mechanism of action of carbamazepine.
The use of the de deckere-ten hoor preparation for study of nicotinic and potassium-evoked dopamine ?-hydroxylase release from the rabbit heart
1980
1. Dopamine β-hydroxylase (DBH) and noradrenaline were determined both in the venous effluent (perfusate) and in the transmyocardial fluid (TMF) collected from the apex of the rabbit isolated heart which was prepared according to De Deckere and Ten Hoor (1977) and perfused with Tyrode's solution at 20 ml/min. 2. Perfusion for 2 min with the nicotinic drug, p-aminophenethyl-trimethylammonium (PAPETA), both in the absence of presence of atropine evoked noradrenaline overflow into the perfusate and TMF that was maximal in the 0–2 min sample and declined from maximum with a t1/2 of 0.6 min. DBH was released into TMF with the maximum from 2–4 min and a t1/2 of decline of 5.6 min. 3. High K-low N…
EFFECTS OF VANADATE ON RESPONSES OF GUINEA-PIG ISOLATED TRACHEA TO SPASMOGENS
1993
Abstract The effects of vanadate on the contractility of the guinea-pig isolated trachea was examined. Vanadate (0·1 Mm) produced a sustained contraction that was abolished in Ca2+-free EGTA (0·1 Mm)-containing physiological salt solution but was resistant to verapamil (1 μm). Vanadate (0·1 Mm) depressed tracheal responses to CaCl2 (in Ca2+-free depolarizing solution), KCl, acetylcholine, histamine and 5-hydroxytryptamine. For vanadate (10 μm), the inhibition of spasmogenic responses only reached statistical significance for histamine and 5-hydroxytryptamine. Caffeine (1 Mm)-induced spasm (trachea at 20°C in the presence of indomethacin (2·8 μm)) was not affected by vanadate (10 μm-0·1 Mm).…
EFFECTS OF PHORBOL 12,13-DIACETATE AND ITS INFLUENCE ON SPASMOGENIC RESPONSES IN NORMAL AND SENSITIZED GUINEA-PIG TRACHEA
1995
Abstract We have studied the effects of phorbol 12,13-diacetate (PDA) and its influence on a variety of spasmogenic responses in trachea isolated in from normal and sensitized guinea-pigs. Tracheal preparations were denuded of epithelium, treated with indomethacin (2·8 μm), and cooled to 20°C. In these experimental conditions, tracheal strips contracted to PDA (0·1 nm-1 μm). Contractions to PDA (1 μm) were greater in sensitized tissues. In normal trachea, contractions to PDA (0·1 μm) were depressed by H-7, 1-(5-isoquinolinyl-sulphonyl)-2-methylpiperazine, (50 μm), amiloride (10 μm), verapamil (10 μm) and Ca2+-free exposure. Similar effects were obtained in sensitized trachea except that PDA…
Troponin I release after intravenous treatment with high furosemide doses plus hypertonic saline solution in decompensated heart failure trial (Tra-H…
2012
Background High values of cardiac troponin in acute decompensated congestive heart failure (ADHF) identify patients at higher risk and worsened prognosis. A cardiac troponin increase during therapy indicates the need for more appropriate intervention, aimed at compensating cardiac disease and effectively minimizing myocardial wall stress and subsequent cytolysis. This study evaluated the effects of an intravenous high dose of furosemide with (group A) or without small volume hypertonic saline solution (HSS) (group B) on myocardial cytolysis in patients with ADHF. Methods A total of 248 consecutive patients with ADHF (148 men, mean age 74.9 ± 10.9 years) were randomly assigned to group A or …
[3H]-DA release evoked by low pH medium and internal H+ accumulation in rat hypothalamic synaptosomes: involvement of calcium ions
2003
The pH fluctuations have been often interpreted as an insufficient regulation or as a consequence of the onset of pathological events, such as ischemia, in which a significant decrease in pH levels occurs. Neurotransmitter release appears to be affected by pH drop significantly. In this study, we investigated the effect of an extracellular and an intracellular acidification on tritiated dopamine release ([3H]-DA release), from superfused rat hypothalamic synaptosomes. When compared to basal release, extracellular acidification, due to a reduction in the external pH of the nominally carbonic-free superfusion media, provoked a significant increase in [3H]-DA release that showed a sensitivenes…
The effects of methacholine and calcium deprivation on the release of the false transmitter, ?-methyladrenaline, from the isolated rabbit heart
1976
1. Anaesthetized rabbits were infused for 20 min with 85 μg · kg−1 · min−1 (±)-α-methyladrenaline. The hearts dissected 15 min after the infusion contained 1.49 μg/g α-methyladrenaline; the endogenous noradrenaline content was correspondingly decreased. 2. Hearts from α-methyladrenaline-infused animals were isolated with the right sympathetic nerves intact and perfused. Ventricular rate, right atrial and right ventricular tensions were recorded using the transverse method. 3. Electrical stimulation (10 Hz, 1 ms, 1 min) of sympathetic nerves, perfusion with the nicotinic drug, p-aminophenethyltrimethylammonium (PAPETA) or perfusion with 54 mM KCl (high K+) solution evoked an output of both α…
Evidence for noradrenaline and adrenaline as sympathetic transmitters in the chicken.
1975
1 The concentrations of noradrenaline and adrenaline in various organs, arterial plasma and venous outflow from isolated hearts of adult chickens have been determined. 2 The relative adrenaline concentrations (percentage of the sum of noradrenaline and adrenaline) in the heart (33%), spleen (16%) and brain (26%) were higher than those found in mammalian organs. Chemical sympathectomy by pretreatment with 6-hydroxydopamine caused a decrease of the noradrenaline and adrenaline concentrations in the heart to 20 and 23% and in the spleen to 16 and 29%, respectively. 3 Stimulation of the right sympathetic nerves, infusion of tyramine or infusion of a modified Tyrode solution containing 108mM K+ …
Effect of different treatments in calcium-free medium on basal tone and contractile responses of guinea pig tracheae.
1995
Acetylcholine (ACh; 0.1 mmol/l) and KCl (80 mmol/l) induce a biphasic contractile response in isolated guinea pig tracheae maintained at 37 degrees C either in the presence or absence of extracellular Ca2+. Exposure of the tissue to Ca(2+)-free solution evokes a significant decrease in basal tone and the sources of Ca2+ appear to be decreased by prolonged agonist stimulation, and even more by successive agonist stimulation. After an incubation period of 20 min in Ca(2+)-containing solution, the response is restored. Mg(2+)-depletion in Ca(2+)-free medium increased the contractile response to ACh, but not to KCl, and delayed the tonic component of the next contraction elicited in Ca(2+)-cont…
Papaverine decreases the efflux of42K in guinea-pig atrial heart muscle
1980
The effects of papaverine on resting potential and efflux of42K were investigated in guinea-pig left atria. Papaverine significantly reduced the potassium efflux in beating preparations. In resting preparations, the efflux of potassium was only slightly affected. However, the resting potential was significantly reduced by papaverine by about 5 mV.