Search results for "Enos"

Identification of Purine Binding Sites on Torpedo Acetylcholine Receptor

1994

Electrophysiological studies from this and other laboratories have suggested a direct action of ATP on nicotinic acetylcholine receptors (nAChR). To determine the site of binding of this purine derivative, we have covalently modified the nAChR from Torpedo marmorata electrocytes employing 2-[3H]-8-azido-ATP as a photoactivable affinity label. Covalently attached radioactivity was predominantly found in the beta-polypeptide of the receptor. Based on the results of protection studies with several nAChR ligands whose target sites at the receptor are known, we conclude that the purine site(s) differ from those of acetylcholine and of physostigmine, galanthamine and related ligands, and those of…

Adenosine and memory storage

1999

Rationale: Caffeine is a non-selective A1/A2 adenosine receptor antagonist which is known to improve cognitive performance in humans. This effect of caffeine has been attributed to its antagonism of adenosine receptors. Objective: The present study was devised to identify the role of A1 and A2A adenosine receptors in the facilitation of memory consolidation in mice performing a passive avoidance task. Methods: Adult albino Swiss male mice were used. The mice were trained in a step-through inhibitory avoidance task in which they were punished by a foot-shock (0.4 mA, 5 Hz, for 3 s) delivered through the grid floor. Caffeine (0.1, 0.3, 1.0 and 3.0 mg/kg), SCH 58261 (0.1, 0.3, 1.0 and 3.0 mg/k…

Severe Brochostenosis by Oral Propafenone Immediately After Commencing Treatment

2011

Propafenone is a membrane-stabilizing agent belonging to a subgroup of the Vaughan Williams class I antidysrhythmic agents, structurally resembling propranolol and characterized by weaker beta-blocking activity. Despite respiratory complications having been reported as examples of side effects, very few reports have been published in the literature.We describe the case of an elderly woman with a history of hypertension and allergy to Parietaria, grass, olive, mites, and with periodic asthmatic manifestations, for whom the administration of oral propafenone for recurrent supraventricular dysrhythmia was associated with the sudden onset of severe bronchostenosis.A 78-year-old woman was freque…

Adenylate storage, metabolism and utilization in coelomic cells of the polychaeteNereis virens (Annelida, polychaeta)

1996

Eleocytes are specialized coelomic cells in nereid annelids which assume a central role during germ cell development. They may contain extremely high concentrations of both adenosine monophosphate (AMP) and adenosine diphosphate (ADP) (each >10 μmol/ml of cell vol.), whereas the adenosine triphosphate (ATP) content is comparatively low (0.8 μmol/ml cell vol.).31P nuclear magnetic, resonance (NMR) studies of living eleocytes suggest the compartmentalization of both AMP and ADP in the large acidic vacuole characteristic for this cell type. Eleocytes are thus capable of storing high concentrations of ADP and AMP without inhibiting energy metabolism, by sequestering these compounds in a separat…

Inhibitory responses to exogenous adenosine in murine proximal and distal colon

2006

The aims of the present study were firstly, to characterize pharmacologically the subtypes of P(1) purinoreceptors involved in the inhibitory effects induced by exogenous adenosine in longitudinal smooth muscle of mouse colon, and secondly, to examine differences in the function and distribution of these receptors between proximal and distal colon. Adenosine (100 microM-3 mM) caused a concentration-dependent reduction of the amplitude of spontaneous contractions in the proximal colon, and muscular relaxation in the distal colon. In the proximal colon, adenosine effects were antagonized by a selective A(1) receptor antagonist, 1,3-dipropyl-8-cyclopentylxanthine (DPCPX, 10 nM), but were not m…

P1 and P2 receptors in the rat duodenal smooth muscle

1989

Uncoupling of endothelial NO synthase in atherosclerosis and vascular disease.

2013

Nitric oxide (NO) produced by the endothelial NO synthase (eNOS) is an antihypertensive, antithrombotic and anti-atherosclerotic molecule. Hypercholesterolemia leads to a reduction in vascular NO bioavailability. This is attributed to a dysfunction of the eNOS enzyme and a reduced eNOS activity. NADPH oxidase-mediated oxidative stress leads to oxidation of tetrahydrobiopterin (BH4), the essential cofactor of eNOS. In BH4 deficiency, oxygen reduction uncouples from NO synthesis, thereby converting eNOS to a superoxide-producing enzyme. As a consequence of eNOS uncoupling, NO production is reduced and the pre-existing oxidative stress is enhanced, which contribute significantly to atherogenes…

Adrenoceptor-mediated changes of excitation and contraction in isolated heart muscle preparations.

1989

The inotropic effects of sympathetic stimulation on the heart are mainly ascribed to the activation of beta-adrenoceptors. However, several findings suggest that alpha-adrenoceptors also may help mediate the inotropic response to catecholamines under certain conditions. The onset of the positive inotropic effect mediated by beta-adrenoceptors occurs within seconds and is associated with a faster rate of relaxation. Both beta 1- and beta 2-adrenoceptors are stimulatorily coupled to the enzyme adenylate cyclase, thereby leading to the generation of cyclic AMP. Cyclic AMP increases the slow inward calcium current and enhances the uptake of calcium into the sarcoplasmic reticulum. GTP-binding p…

Evidence that ATP or a related purine is an excitatory neurotransmitter in the longitudinal muscle of mouse distal colon

2007

Background and purpose: This study analysed the contribution of the purinergic system to enteric neurotransmission in the longitudinal muscle of mouse distal colon. Experimental approach: Motor responses to exogenous ATP and to nerve stimulation in vitro were assessed as changes in isometric tension. Key results: ATP induced a concentration-dependent contraction, reduced by 4-[[4-formyl-5-hydroxy-6-methyl-3-[(phosphonooxy)methyl]-2-pyridinyl]azo]-1,3-benzene disulphonic acid (PPADS), suramin, P2Y purinoreceptor desensitisation with adenosine 5’-O-2-thiodiphosphate (ADPβS), and atropine, but unaffected by P2X purinoceptor desensitisation with α,β-methylene ATP (α,β-meATP) and by 2,2-dimethyl…

AVE3085, an enhancer of endothelial nitric oxide synthase, restores endothelial function and reduces blood pressure in spontaneously hypertensive rats

2011

BACKGROUND AND PURPOSE Nitric oxide (NO) plays an important role in endothelial function, and impaired NO production is involved in hypertension. Therefore, compounds that regulate endothelial NO synthase (eNOS) may be of therapeutic benefit. A novel, low molecular weight compound AVE3085 is a recently developed compound with the ability to enhance eNOS transcription. The present study investigated the effects of AVE3085 in endothelial dysfunction associated with hypertension. EXPERIMENTAL APPROACH Spontaneously hypertensive rats (SHRs) were treated with AVE 3085 (10 mg·kg·day−1, orally) for 4 weeks. Isometric force measurement was performed on rings of isolated aortae in organ baths. Prote…