Search results for "RECEPTORS"
showing 10 items of 3254 documents
The release of choline from phospholipids mediated by beta-adrenoceptor activation in isolated hearts.
1986
The resting efflux of choline into the perfusate (Tyrode's solution) of isolated hearts was equal to the rate, at which choline was liberated from phospholipid degradation (Lindmar et al. 1986). Infusion of isoprenaline (2 X 10(-7) mol/l), forskolin (1-3 X 10(-6) mol/l) or 3-isobutyl-1-methylxanthine (IBMX; 3 X 10(-4) mol/l) for 40 min markedly enhanced the efflux of choline. The increase was linear during the experimental period and, in the case of isoprenaline, was blocked by 3 X 10(-7) mol/l atenolol. In the guinea-pig heart, IBMX at a threshold concentration of 10(-4) mol/l shifted the concentration-response curve for the effect of forskolin on the efflux of choline to the left by one l…
Histamine and spontaneously released mast cell granules affect the cell growth of human hepatocellular carcinoma cells
2007
The role of mast cells in tumor growth is still controversial. In this study we analyzed the effects of both histamine and pre-formed mediators spontaneously released by mast cells on the growth of two human hepatocellular carcinoma cell lines, HA22T/VGH and HuH-6, with different characteristics of differentiation, biological behavior and genetic defects. We showed that total mast cell releasate, exocytosed granules (granule remnants) and histamine reduced cell viability and proliferation in HuH-6 cells. In contrast, in HA22T/VGH cells granule remnants and histamine induced a weak but significant increase in cell growth. We showed that both cell lines expressed histamine receptors H(1) and …
Expression of Wild-Type and Variant Estrogen Receptor Alpha in Liver Carcinogenesis and Tumor Progression.
2011
Although estrogen receptors (ERs) are expressed in human hepatocellular carcinoma (HCC), several clinical trials have failed to demonstrate the efficacy of antiestrogen treatment in HCC patients. Recently, the identification of several ER splicing variants has enlightened the complex nature of estrogen signaling in peripheral tissues; this may help understanding estrogen role in either nontumoral or malignant nonclassical target organs, including liver. In this work we have investigated mRNA expression of wild-type and splice variants of ERα in nontumoral, cirrhotic, and malignant human liver, as well as in HCC cell lines, using an exon-specific reverse transcription polymerase chain reacti…
Effects of Norepinephrine and Cardiotrophin-1 on Phospholipase D Activity and Incorporation of Myristic Acid Into Phosphatidylcholine in Rat Heart
2004
The present study is part of a project on phospholipase D (PLD) in cardiac hypertrophy and analyzed effects on PLD activity of two growth stimuli, norepinephrine (NE) and cardiotrophin-1 (CT-1), in incubated rat heart. Phosphatidylcholine (PC) was labeled by 3H-myristic acid. PLD produced 3H-phosphatidylethanol (3H-PEth) from 3H-PC in the presence of ethanol and maintained a basal formation of 3H-PEth. Short-term and long-term exposure to NE for 2 or 13 h, respectively, enhanced the formation of 3H-PEth, which was blocked by prazosin. Long-term pretreatment with NE or CT-1 increased the incorporation of 3H-myristic acid into PC, which was blocked by atenolol. When the 3H-PEth formation was …
Medical significance of peroxisome proliferator-activated receptors.
1999
Peroxisome proliferator-activated receptors (PPAR) were discovered in 1990, ending 25 years of uncertainty about the molecular mechanisms of peroxisome proliferation. Subsequently, PPARs have improved our understanding of adipocyte differentiation. But there is more to PPARs than solving a puzzle about an organelle (the peroxisome) long considered an oddity, and their medical significance goes beyond obesity too. Enhanced PPAR type alpha expression protects against cardiovascular disorders though the role of enhanced PPARgamma expression seems less favourable. PPAR mechanisms, mainly via induction of more differentiated cell phenotypes, protect against some cancers. The differentiation of m…
Expression of inhibitory glycine receptors in postnatal rat cerebral cortex.
1993
The developmental expression of inhibitory glycine receptors was analyzed in postnatal rat cerebral cortex using the specific monoclonal antibody, MAb 4a. This antibody defines an epitope common to all known glycine receptor alpha-subunits. At birth, high levels of immunoreactivity were found, which transiently increased during the second postnatal week, but subsequently declined to low adult levels. Biochemical analysis of the MAb 4a antigen from parietal areas indicates that cortical glycine receptors correspond to the neonatal receptor isoform previously identified in spinal cord of newborn animals. Immunocytochemistry showed that, within 2 weeks after birth, MAb 4a-reactive glycine rece…
Chelation of synaptic zinc induces overexcitation in the hilar mossy cells of the rat hippocampus.
2004
Complete removal of synaptic zinc by the chelator dietyldithiocarbamate (DEDTC; 500 mg/kg i.p.) in rat was followed by convulsive behaviour including wet dog shakes alternating immobility. Histological analysis 1 day after DEDTC administration detected expression of heat shock protein in the hippocampus restricted to hilar cells. These cells colocalize the marker for neurons and the glutamate receptor GluR2/3 showing that they are excitatory neurons. Additionally, they projected to the contralateral dentate gyrus. Therefore, they correspond to hilar mossy cells. These data show that the synaptic zinc has a role in normal hippocampus avoiding overexcitation, that would impair functionality e…
Direct and neuromodulatory effects of histamine on isolated goat cerebral arteries.
1992
1. The effects of histamine on isolated goat middle cerebral artery were examined using two experimental approaches: recording of isometric tension and measurement of [3H]-noradrenaline efflux. 2. Cumulative addition of histamine (10(-7)-3 x 10(-2)M) and 2-pyridylethylamine (2-PEA, 10(-6)-3 x 10(-2)M) produced concentration-dependent contractile responses. Preincubation with diphenhydramine (10(-7), 10(-6)M) or cimetidine (10(-7), 10(-6)M) competitively inhibited the histamine-induced contractile response. 3. Endothelium denudation enhanced the contractile effects of histamine. 4. Transmural electrical stimulation elicited contractions which were enhanced by histamine (10(-7)M), 2-PEA (10(-…
Erythropoietin in Traumatic Brain Injury: An Answer Will Come Soon
2015
Traumatic brain injury (TBI) is a major cause of morbidity and mortality in the United States. It is estimated that each year TBIs are associated with 1.1 million emergency department visits, 235,000 hospitalizations, and 50,000 deaths (1). Despite improvements in medical interventions, there are still no neuroprotective agents available to counteract secondary or delayed damage to the traumatically injured human brain or to promote its repair. TBI encompasses heterogeneous etiologic, anatomical, and molecular patterns of injury that exhibit different propensities to cause cerebral damage. Without careful consideration of individual injuries, the results of therapeutic trials remain difficu…
Pharmacological investigation into the effects of histamine and histamine analogues on guinea-pig and rat colon in vitro.
1986
The effects of histamine and specific histamine agonists has been examined on isolated longitudinal colon strips of guinea-pig and rat. Histamine and 2-pyridyl-ethylamine but not 4 methylhistamine produced a concentration-related contractile response in the guinea-pig colon. The H1-antagonist clemizole antagonized competitively the effect of histamine but the H2-antagonist ranitidine did not modify the dose-response curve to histamine in the guinea-pig colon. Atropine, hexamethonium, prazosin and propranolol failed to modify the contractile response to histamine. Tone induced with KCl in guinea-pig isolated colon was not modified by histamine agonists even in tissues pretreated with clemizo…