Search results for "ammonium"
showing 10 items of 1070 documents
Inhibition of the mechanical activity of mouse ileum by cactus pear (Opuntia Ficus Indica, L, Mill.) fruit extract and its pigment indicaxanthin.
2010
We investigated, using an organ bath technique, the effects of a hydrophilic extract from Opuntia ficus indica fruit pulp (cactus fruit extract, CFE) on the motility of mouse ileum, and researched the extract component(s) responsible for the observed responses. CFE (10-320 mg of fresh fruit pulp equivalents/mL of organ bath) reduced dose-dependently the spontaneous contractions. This effect was unaffected by tetrodotoxin, a neuronal blocker, N(omega)-nitro-l-arginine methyl ester, a nitric oxide synthase blocker, tetraethylammonium, a potassium channel blocker, or atropine, a muscarinic receptor antagonist. CFE also reduced the contractions evoked by carbachol, without affecting the contrac…
Acute ammonia toxicity is mediated by the NMDA type of glutamate receptors
1992
AbstractPrevious experiments in our laboratory suggested that ammonium toxicity could be mediated by the NMDA type of glutamate receptors. To assess this hypothesis we tested if MK-801, a specific antagonist of the NMDA receptor, is able to prevent ammonium toxicity. Mice and rats were injected i.p. with 12 and 7 mmol/kg of ammonium acetate, respectively, 73% of the mice and 70% of the rats died. However, when the animals were injected i.p. with 2 mg/kg of MK-801, 15 min before ammonium injection, only 5% of the mice and 15% of the rats died. The remarkable protection afforded by MK-801 indicates that ammonia toxicity is mediated by the NMDA receptor.
Role of K+ and Ca2+ fluxes in the cerebroarterial vasoactive effects of sildenafil
2007
The aim of this study was to assess the role of K(+) and Ca(2+) fluxes in the cerebroarterial vasoactive effects of the phosphodiesterase-5 inhibitor sildenafil. We used isolated rabbit basilar arteries to assess the effects of extracellular K(+) raising on sildenafil-induced vasodilatation, and studied the pharmacological interaction of sildenafil with selective modulators of membrane K(+) and Ca(2+) channels. Expression of Kv1 subunits of K(+) channels was assessed at messenger and protein levels. Parallel experiments were carried out with zaprinast for comparison. Sildenafil (10 nM-0.1 mM) induced concentration-dependent relaxation of endothelin-1 (10 nM)-precontracted arteries, which wa…
Selective regional distribution of tubulin induced in cerebrum by hyperammonemia
1989
Ingestion of ammonium induces hyperammonemia which increases tubulin content in cerebrum but not in cerebellum. We have dissected 11 discrete areas of cerebrum and quantified the tubulin content in control and hyperammonemic rats. An heterogeneity in the induction of tubulin is shown. The areas more affected are ventral hippocampus, dorsal hippocampus, hypothalamus, septum, reticular formation and frontal cortex, in which tubulin content increased by 63%, 27%, 32%, 48%, 45%, and 25%, respectively, after two months of feeding the ammonium diet.
Enhanced terminal room disinfection and acquisition and infection caused by multidrug-resistant organisms and Clostridium difficile (the Benefits of …
2017
Summary Background Patients admitted to hospital can acquire multidrug-resistant organisms and Clostridium difficile from inadequately disinfected environmental surfaces. We determined the effect of three enhanced strategies for terminal room disinfection (disinfection of a room between occupying patients) on acquisition and infection due to meticillin-resistant Staphylococcus aureus , vancomycin-resistant enterococci, C difficile , and multidrug-resistant Acinetobacter . Methods We did a pragmatic, cluster-randomised, crossover trial at nine hospitals in the southeastern USA. Rooms from which a patient with infection or colonisation with a target organism was discharged were terminally dis…
Nicotine receptors do not modulate the 3H-noradrenaline release from the isolated rat heart evoked by sympathetic nerve stimulation.
1982
Isolated rat hearts with the right sympathetic nerves attached were perfused at a constant flow rate of 7 ml/min with Tyrode's solution. (-)-3H-Noradrenaline (final concentration 10–13.9 nM) was infused for 10 min to label the noradrenaline stores. After wash-out the sympathetic nerves were stimulated electrically (3 Hz, 180 impulses, 1 ms, 20–30 mA) three times (S1–S3) at intervals of 15 min. 3H-Noradrenaline and its metabolites were determined by liquid scintillation counting according to Graefe et al. (1973). Both, nicotine 50 μM and p-aminophenethyltrimethylammonium (PAPETA) 30 μM, enhanced the 3H-noradrenaline overflow in the absence of nerve stimulation. The effect of PAPETA was bipha…
Exercise and recovery in frog muscle: metabolism of PCr, adenine nucleotides, and related compounds
1996
The effects of exercise (swimming), fatigue, and recovery on the intracellular pH (pHi), energy-rich phosphates, and related metabolites were studied in the gastrocnemius muscle of common frogs (Rana temporaria) at 20 degrees C. Exercise caused a rapid decrease in the content of phosphocreatine (PCr) and a corresponding increase in that of Pi. The ATP level remained virtually constant for 1 min; its precipitous decrease during the following minute was associated with a rise in the contents of inosine 5'-monophosphate (IMP) and NH4+, indicating a marked activation of AMP deaminase. Five minutes of swimming caused severe fatigue, which was correlated with decreases in muscle PCr (-85%), ATP …
Diabetes impairs the atrial natriuretic peptide relaxant action mediated by potassium channels and prostacyclin in the rabbit renal artery.
2012
Diabetes is associated with increased prevalence of hypertension, cardiovascular and renal disease. Atrial natriuretic peptide (ANP) plays an important role in cardiovascular pathophysiology and is claimed to have cardioprotective and renoprotective effect in diabetic patients. The working hypothesis was that alloxan-induced diabetes might modify the vascular effects of ANP in isolated rabbit renal arteries and the mechanisms involved in such actions. Plasma ANP levels were higher in diabetic rabbits than in control rabbits. ANP (10(-12)-10(-7)M) induced a relaxation of precontracted renal arteries, which was lower in diabetic than in control rabbits. In arteries from both groups of animals…
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…
Characterization of the muscarine receptors involved in the modulation of serotonin release from the vascularly perfused small intestine of guinea pi…
1989
Isolated small intestinal segments of the guinea pig were arterially perfused and the release of 5-hydroxytryptamine (5-HT) and its metabolite 5-hydroxyindoleacetic acid (5-HIAA) into the portal venous effluent measured by HPLC with electrochemical detection. Test substances were applied via the arterial perfusion medium. McN-A-343, pilocarpine and oxotremorine inhibited concentration-dependently the outflow of 5-HT and 5-HIAA. Pirenzepine (0.03-0.1 mumol/l) which can discriminate between M1 and M2-receptor subtypes antagonized completely this inhibitory effect. In the presence of 1 mumol/l tetrodotoxin (TTx), all three muscarine receptor agonists increased the outflow of 5-HT and 5-HIAA. O…