Search results for "purinergic"

Nitrergic and purinergic interplay in inhibitory transmission in rat gastric fundus.

2007

Summary 1  This study was undertaken to analyse the involvement of ATP in non-adrenergic non- cholinergic (NANC) relaxation and possible interplay between nitrergic and purinergic systems in rat gastric fundus. 2  Experiments were performed in vitro on strips of longitudinal muscle from rat gastric fundus, recording the mechanical activity as changes in isometric force. In addition, NO release induced by different experimental conditions was assayed. 3  Under NANC conditions in serotonin-precontracted strips, electrical field stimulation (EFS) elicited a tetrodotoxin (TTX)-sensitive relaxation accompanied by nitric oxide (NO) release. This effect was antagonized by pretreatment with the NO …

Inhibitory purinergic transmission in mouse caecum: Role for P2Y1 receptors as prejunctional modulators of ATP release

2007

Using conventional microelectrode recording techniques, we investigated, in the circular muscle of the mouse caecum, the neurotransmitter(s) involved in the neurally-evoked inhibitory junction potentials (IJPs) and the existence of possible prejunctional mechanisms controlling neurotransmitter release. Electrical field stimulation with single pulses elicited IJPs, consisting only of a "fast" hyperpolarization, while using train stimuli (30-50 Hz) the initial fast hyperpolarization was followed by a slower hyperpolarization. The fast and the slow component were selectively antagonized by apamin, a blocker of calcium-activated potassium channels, and N(omega)-nitro-l-arginine methyl ester (l-…

Mechanisms underlying hyperpolarization evoked by P2Y receptor activation in mouse distal colon

2006

In murine colonic circular muscle, ATP mediates fast component of the nerve-evoked inhibitory junction potentials, via activation of P2Y receptors and opening of apamin-sensitive Ca2+-dependent K+ channels. We investigated, using microelectrode recordings, the intracellular events following P2Y-receptor activation by electrical field stimulation or by adenosine 5'-O-2-thiodiphosphate (ADPbetaS), ATP stable analogue. The fast-inhibitory junction potential amplitude was reduced by thapsigargin or ciclopiazonic acid (CPA), sarcoplasmic reticulum Ca2+-ATPase inhibitors, by ryanodine, which inhibits Ca2+ release from ryanodine-sensitive stores, and by 9-(tetrahydro-2-furanyl)-9H-purin-6-amine (S…

Activation of P2Y receptors by ATP and by its analogue, ADPbetaS, triggers two calcium signal pathways in the longitudinal muscle of mouse distal col…

2008

Our previous research showed that ATP and adenosine 5'-O-2-thiodiphosphate (ADPbetaS) induce contractile effects in the longitudinal muscle of mouse distal colon via activation of P2Y receptors which are not P2Y(1) or P2Y(12) subtypes. This study investigated the nature of the P2Y receptor subtype(s) and the mechanisms leading to the intracellular calcium concentration increase necessary to trigger muscular contraction. Motor responses of mouse colonic longitudinal muscle to P2Y receptor agonists were examined in vitro as changes in isometric tension. ATP or ADPbetaS induced muscular contraction, which was not affected by P2Y(11) or P2Y(13) selective antagonists. Calcium-free solution or th…

Involvement of the P2X7 purinergic receptor in colonic motor dysfunction associated with bowel inflammation in rats

2014

Background and Purpose Recent evidence indicates an involvement of P2X7 purinergic receptor (P2X7R) in the fine tuning of immune functions, as well as in driving enteric neuron apoptosis under intestinal inflammation. However, the participation of this receptor in the regulation of enteric neuromuscular functions remains undetermined. This study was aimed at investigating the role of P2X7Rs in the control of colonic motility in experimental colitis. Experimental Approach Colitis was induced in rats by 2,4-dinitrobenzenesulfonic acid. P2X7R distribution was examined by immunofluorescence analysis. The effects of A804598 (selective P2X7R antagonist) and BzATP (P2X7R agonist) were tested on co…

Effects of clopidogrel vs. prasugrel vs. ticagrelor on endothelial function, inflammatory parameters, and platelet function in patients with acute co…

2020

Abstract Aims In a randomized, parallel, blinded study, we investigate the impact of clopidogrel, prasugrel, or ticagrelor on peripheral endothelial function in patients undergoing stenting for an acute coronary syndrome. Methods and results The primary endpoint of the study was the change in endothelium-dependent flow-mediated dilation (FMD) following stenting. A total of 90 patients (age 62 ± 9 years, 81 males, 22 diabetics, 49 non-ST elevation myocardial infarctions) were enrolled. There were no significant differences among groups in any clinical parameter. Acutely before stenting, all three drugs improved FMD without differences between groups (P = 0.73). Stenting blunted FMD in the cl…

Can new generation P2Y12 inhibitors play a role in microvascular obstruction in STEMI?

2016

Antithrombotic Therapy in Patients with Atrial Fibrillation and Acute Coronary Syndrome Treated Medically or with Percutaneous Coronary Intervention …

2019

Background: The safety and efficacy of antithrombotic regimens may differ between patients with atrial fibrillation who have acute coronary syndromes (ACS), treated medically or with percutaneous coronary intervention (PCI), and those undergoing elective PCI. Methods: Using a 2×2 factorial design, we compared apixaban with vitamin K antagonists and aspirin with placebo in patients with atrial fibrillation who had ACS or were undergoing PCI and were receiving a P2Y 12 inhibitor. We explored bleeding, death and hospitalization, as well as death and ischemic events, by antithrombotic strategy in 3 prespecified subgroups: patients with ACS treated medically, patients with ACS treated with PCI,…

Pretreatment with prasugrel in non-ST-segment elevation acute coronary syndromes

2013

Item does not contain fulltext BACKGROUND: Although P2Y12 antagonists are effective in patients with non-ST-segment elevation (NSTE) acute coronary syndromes, the effect of the timing of administration--before or after coronary angiography--is not known. We evaluated the effect of administering the P2Y12 antagonist prasugrel at the time of diagnosis versus administering it after the coronary angiography if percutaneous coronary intervention (PCI) was indicated. METHODS: We enrolled 4033 patients with NSTE acute coronary syndromes and a positive troponin level who were scheduled to undergo coronary angiography within 2 to 48 hours after randomization. Patients were randomly assigned to recei…

Antithrombotic Therapy after Acute Coronary Syndrome or PCI in Atrial Fibrillation

2019

Background: Appropriate antithrombotic regimens for patients with atrial fibrillation who have an acute coronary syndrome or have undergone percutaneous coronary intervention (PCI) are unclear. Methods: In an international trial with a two-by-two factorial design, we randomly assigned patients with atrial fibrillation who had an acute coronary syndrome or had undergone PCI and were planning to take a P2Y12 inhibitor to receive apixaban or a vitamin K antagonist and to receive aspirin or matching placebo for 6 months. The primary outcome was major or clinically relevant nonmajor bleeding. Secondary outcomes included death or hospitalization and a composite of ischemic events. Results: Enroll…