Search results for " ALPHA"
showing 10 items of 1610 documents
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-…
Anti-inflammatory effects of cerebrocrast in a model of rat paw edema and on mononuclear THP-1 cells.
2002
Cerebrocrast (IOS 1.1212; 4-[2-(difluoromethoxy)phenyl]-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylic acid di(2-propoxyethyl) diester) is a novel derivative of 1,4-dihydropyridine, which does not antagonize Ca(2+) influx in neuronal tissues. Since several classical dihydropyridines possess anti-inflammatory properties, we first studied the effects of cerebrocrast in a model of rat paw edema induced by carrageenan. Cerebrocrast had a preventative effect in this model of inflammation, with maximal activity (32-45% inhibition) in the 0.1-0.25 mg kg(-1) range. It was ineffective when added after the injection of carrageenan. Subsequent in vitro experiments showed that cerebrocrast in the mi…
Estradiol selectively stimulates endothelial prostacyclin production through estrogen receptor-α
2010
Estradiol (E2) acts on the endothelium to promote vasodilatation through the release of several compounds, including prostanoids, which are products of arachidonic acid metabolism. Among these, prostacyclin (PGI2) and thromboxane A2 (TXA2) exert opposite effects on vascular tone. The role of different estrogen receptors (ERs) in the PGI2/TXA2 balance, however, has not been fully elucidated. Our study sought to uncover whether E2 enhances basal production of PGI2 or TXA2 in cultured human umbilical vein endothelial cells (HUVECs), to analyze the enzymatic mechanisms involved, and to evaluate the different roles of both types of ERs (ERα and ERβ). HUVECs were exposed to E2, selective ERα (1,3…
Direct evidence of leukocyte adhesion in arterioles by angiotensin II
2004
AbstractAlthough leukocytes adhere in arteries in various vascular diseases, to date no endogenous proinflammatory molecule has been identified to initiate leukocyte adhesion in the arterial vasculature. This study was undertaken to assess angiotensin II (Ang II)-induced leukocyte adhesion in arterioles in vivo. Rats received intraperitoneal injections of Ang II; 4 hours later, leukocyte recruitment in mesenteric microcirculation was examined using intravital microscopy. Ang II (1 nM) produced significant arteriolar leukocyte adhesion of mononuclear cells. Using function-blocking monoclonal antibodies (mAbs) against different rat cell adhesion molecules (CAMs), we discovered that this effec…
Impaired Vitamin D Signaling in Endothelial Cell Leads to an Enhanced Leukocyte-Endothelium Interplay: Implications for Atherosclerosis Development
2015
Endothelial cell activation leading to leukocyte recruitment and adhesion plays an essential role in the initiation and progression of atherosclerosis. Vitamin D has cardioprotective actions, while its deficiency is a risk factor for the progression of cardiovascular damage. Our aim was to assess the role of basal levels of vitamin D receptor (VDR) on the early leukocyte recruitment and related endothelial cell-adhesion-molecule expression, as essential prerequisites for the onset of atherosclerosis. Knockdown of VDR in endothelial cells (shVDR) led to endothelial cell activation, characterized by upregulation of VCAM-1, ICAM-1 and IL-6, decreased peripheral blood mononuclear cell (PBMC) ro…
Contribution of both ?- and ?-adrenoceptors to the inotropic effects of catecholamines in the rabbit heart
1992
The functional role of alpha-adrenoceptors was investigated in different parts of the rabbit heart. Phenylephrine (PE) caused a marked increase in force of contraction (Fc) and a prolongation of the action potential (AP) in preparations from the left atrium and the right ventricle. The response was less pronounced in the right atrium and in the left ventricle, whereas APs of spontaneously beating sinoatrial preparations remained completely unchanged. Phentolamine as well as the diesters phorbol 12,13 dibutyrate (PDBu) or 12-O-tetradecanoyl-phorbol-13-acetate (TPA) eliminated the effects of PE. The contribution of alpha-adrenoceptors to the effects of adrenaline (Adr) and noradrenaline (NA) …
Modulation of cytosolic free calcium concentration by ?1-adrenoceptors in rat atrial cells
1992
The effects of α1-adrenoceptor stimulation by phenylephrine (PE) and β-adrenoceptor stimulation by isoprenaline (ISO) on Ca2+ current (ICa) and free intracellular Ca2+ concentration ([Ca2+]i) were studied in isolated atrial myocytes from rat hearts. PE did not significantly affect the magnitude of ICa, whereas large increases of peak ICa were observed in response to ISO. In electrically driven cells, PE evoked a concentration-dependent, gradual increase in diastolic [Ca2+]i and, initially, an increase in the height of peak [Ca2+]i transients. When the diastolic [Ca2+]i was increased to a greater extent, the amplitude of [Ca2+]i transients was decreased. Simultaneous measurements of [Ca2+]i …
Polymorphism in the peroxisome proliferator-activated receptor ? gene influences the risk for Alzheimer?s disease
2003
The peroxisome proliferator-activated receptor alpha (PPAR-alpha) is a member of the steroid hormone super family of ligand-inducible transcription factors, involved in glucose and lipid metabolism. We screened for polymorphisms in the PPAR-alpha gene and detected two known polymorphisms located in exon 5 and intron 7. These polymorphisms were investigated for their possible association with Alzheimer's disease (AD) and for their effect in carriers of an insulin gene (INS) polymorphism. The PPAR-alpha C --G polymorphism in exon 5 (L162V) was associated with AD, in that the V-allele was more frequent in AD patients than in healthy subjects. Further data analysis revealed that carriers of an …
Increase by ?-adrenolytic drugs of acetylcholine release evoked by field stimulation of the guinea-pig ileum
1979
The release of acetylcholine evoked by field stimulation of the guinea-pig ileum (3 Hz) is increased by yohimbine and tolazoline but not affected by phentolamine. It is proposed that yohimbine and tolazoline by blocking alpha-adrenoceptors of the cholinergic nerves abolish the inhibition caused by endogenous noradrenaline, and thus facilitate the output of acetylcholine.
Re-treatment of Patients With Chronic Hepatitis C Who Do Not Respond to Peginterferon-[alpha]2b: A Randomized Trial
2009
BACKGROUND Many patients with chronic hepatitis C have not responded to therapy with pegylated interferon plus ribavirin. OBJECTIVE To evaluate use of peginterferon-alpha2a plus ribavirin to re-treat nonresponders to peginterferon-alpha2b plus ribavirin. DESIGN Randomized, parallel-group trial conducted between September 2003 and February 2007. Patients and researchers were not blinded to intervention assignment. Random assignment was centralized, computer-generated, and stratified by geographic region, hepatitis C virus (HCV) genotype, and histologic diagnosis. SETTING 106 international centers. PATIENTS 950 nonresponders to 12 or more weeks of therapy with peginterferon-alpha2b plus ribav…