Search results for "potassium chloride"
showing 10 items of 87 documents
Modulatory role of magnesium on the contractile response of rat aorta to several agonists in normal and calcium-free medium.
1993
Abstract Acute withdrawal of external Mg2+ increased basal tone of rat isolated aorta incubated in the presence of Ca2+. Above normal levels of Mg2+ (1–4 Mm) inhibited basal tone while much higher levels of the divalent cation (64–256 Mm) evoked contractile responses regardless of the presence of Ca2+. Contractile responses to noradrenaline (1μm) and KCl (80 Mm) were inhibited by addition of cumulative concentrations of Mg2+. Acetylcholine-induced contractions in the presence of physiological concentrations of Mg2+ (1 Mm) decreased gradually to the basal tone, but a sustained contraction was observed in the absence of this ion. In Ca2+-free medium, acetylcholine-induced phasic responses ind…
Calcium dependence of the contraction produced by endothelin (ET-1) in isolated guinea-pig trachea.
1990
Endothelin (ET-1, 1 pM to 0.1 microM) produced a concentration-dependent contraction of isolated guinea-pig trachea. BAY K 8644 (1 microM) did not significantly alter the concentration-response curve for ET-1. Incubation with nicardipine (10 microM) partly inhibited responses to low concentrations (10 pM to 1 nM) of ET-1 while verapamil (10 microM) and diltiazem (10 microM) were ineffective. La3+ (10 microM) and Cd2+ (10 microM) preferentially depressed the responses evoked by high concentrations (30 nM-0.1 microM) of ET-1 without affecting the responses evoked by low concentrations of the peptide. Incubation in Ca2(+)-free (with EDTA, 1 mM) medium resulted in suppression of the responses e…
U-46619-induced potentiation of noradrenergic constriction in the human saphenous vein: antagonism by thromboxane receptor blockade.
2001
Objective: We investigated the potentiating effect of U-46619, a synthetic analogue of thromboxane A2 (TXA2), on the adrenergic responses in human saphenous vein. Methods: Saphenous vein rings were obtained from 35 patients undergoing coronary artery bypass surgery. The rings were suspended in organ bath chambers for isometric recording of tension. Results: U-46619 (10−10–3×10−7 mol/l) produced concentration-dependent and endothelium-independent contractile responses. U-46619 (10−10 mol/l) potentiated the contractions elicited by electrical stimulation and potassium chloride, and produced leftward shifts of the concentration–response curve for noradrenaline. The TXA2 receptor antagonist SQ-…
Effects of high-dose furosemide and small-volume hypertonic saline solution infusion in comparison with a high dose of furosemide as a bolus, in refr…
2000
Background: Diuretics, have been accepted as first-line treatment in refractory heart failure, but a lack of response is a frequent event. A randomised single blind study was performed to evaluate the effects of the combination of high-dose furosemide and small-volume hypertonic saline solution (HSS) infusion in the treatment of refractory NYHA class IV congestive heart failure (CHF). Materials and methods: Sixty patients (21 F/39 M) with refractory CHF (NYHA class IV) of different etiologies, unresponsive to high oral doses of furosemide, ACE-inhibitors, digitalis, and nitrates, aged 65–90 years, were enrolled. They had to have an ejection fraction (EF) < 35%, serum creatinine < 2 mg/dl, B…
Non-specific Hyperreactivity to Pharmacological Stimuli in Tracheal and Lung Parenchymal Strips of Actively Sensitized Guinea-pigs
1989
Abstract The responsiveness of tracheal and lung parenchymal strips isolated from actively sensitized guinea-pigs to CaCl2 (in K+-depolarized tissue), KCl, acetylcholine and histamine was compared with that of strips from unsensitized animals. The concentration-response curves to the mentioned agonists exhibited, in the sensitized group, a left upward displacement (greater maximal effect, lesser effective concentration 50% and a steeper slope) compared with those obtained in the unsensitized group. These results indicate the existence of a non-specific increase in responsiveness in the airway smooth muscle from sensitized animals.
Evidence for the neuronal origin of immunoreactive interleukin-1 beta released by rat hypothalamic explants.
1996
In this study, we have investigated the release of immunoreactive interleukin-1 beta (irIL-1 beta) from the rat hypothalamus in vitro. It was found that (1) tissue explants release sizable amounts of irIL-1 beta (ranging from 0.43 to 0.52 pg/mg of wet tissue) in 20 min incubations; (2) basal release in significantly increased by depolarization induced with 56 mM KCl; (3) K(+)-induced irIL-1 beta release is inhibited by the specific blocker of N-type calcium channels, omega-conotoxin, and by verapamil, but not by nifedipine; (4) K(+)-induced release is also inhibited by the Na+ channel blockers tetrodotoxin and lidocaine; (5) irIL-1 beta release is significantly increased by noradrenalin; su…
Effect of Divalent Cations on the Contractile Response of Rat Aorta to Depolarization before and after Nifedipine Treatment
1996
The influence of the divalent cations, Ca2+, Mg2+ and Ba2+, on the contractile response of the rat aorta to KCl and on the recovery of this response after nifedipine treatment was analyzed. KCl (80 mmol/l) promoted a two-phase (phasic and tonic) contractile response in Krebs solution but, as expected, no contractile response in Ca(2+)-free medium. In Mg(2+)-free medium, the phasic response to KCl was unaffected but the tonic one decreased slowly, suggesting that a long incubation time in the absence of Mg2+ (65 min) promotes a loss of or a change in the intracellular distribution of this ion that modifies Ca2+ entry through L channels or Ca2+ handling. Ba2+ (1.8 mmol/l) contracted the rat a…
Effects of Cortical Spreading Depression on Cortical Blood Flow, Impedance, DC Potential, and Infarct Size in a Rat Venous Infarct Model
2000
A cortical venous infarction model has been evaluated as to the degree of regional flow reduction and by studying effects of cortical spreading depression (CSD). Two adjacent cortical veins were occluded photochemically with rose bengal and fiberoptic illumination. Seven rats served to demonstrate effects on regional cortical blood flow using laser Doppler scanning. In 36 rats local CBF, DC potential, and brain tissue impedance were measured continuously for 75 min after vein occlusion. No, 3, or 10 CSD waves were induced by potassium chloride injection during the initial 75 min. Rats were compared for spontaneous CSDs; baseline local CBF, CBF, and impedance response to CSD; and infarct vol…
Suppression by cholinesterase inhibition of a Ca(2+)-independent efflux of [3H]acetylcholine from the neuromuscular junction of the isolated rat diap…
1992
Abstract Endplate preparations of the left rat hemidiaphragm were incubated with [ 3 H]choline to label neuronal acetylcholine stores. Elevation of the concentration (13.5–135 mmol/l) of extracellular potassium chloride (KC1) stimulated the release of [ 3 H]acetylcholine in a concentration-dependent manner. KC1 (27 mmol/l) still caused a significant efflux of [ 3 H]acetylcholine in a Ca 2+ -free medium. Inhibitors of cholinesterase (physostigmine, diisopropylfluorophosphate) suppressed by 80% this Ca 2+ -independent efflux of [ 3 H]acetylcholine. Vesamicol (10 μmol/l), the blocker of the vesicular acetylcholine carrier, also suppressed the stimulated, Ca 2+ -independent efflux of [ 3 H]acet…
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).…