Search results for "Cyclic GMP"
showing 10 items of 99 documents
Cyclic AMP and cyclic GMP may play opposing roles in influencing force of contraction in mammalian myocardium.
1976
CYCLIC AMP and cyclic GMP have been suggested to play opposing regulatory roles in several biological systems1. Supporting evidence for the yin yang hypothesis of opposing biological regulation has been obtained in sympathetic ganglia2,3 and pyramidal neurones in the rat cerebral cortex4. In the mammalian heart, the role of cyclic AMP in mediating the positive inotropic response to catecholamines was advanced by the observation that the inotropic effect was preceded by an increase in cyclic AMP levels5. On the other hand, the levels of cyclic GMP were found to be increased after cholinergic stimulation6. In frog, oscillations of cyclic AMP7 and cyclic changes in the levels of cyclic AMP and…
Does cyclic GMP mediate the negative inotropic effect of acetylcholine in the heart?
1977
DURING vagal stimulation the pacemaker activity of the heart is diminished. The reduction in heart rate is due to a release of acetylcholine (ACh) from the parasympathetic nerve terminals that increases the permeability of the myocardial cell membrane for potassium ions (for review see ref. 1). This is accompanied by a shortening of the action potential duration in atrial muscle and a diminished calcium uptake2, which in turn results in a negative inotropic effect. Voltage clamp experiments in mammalian atrial muscle have shown that with higher concentrations of ACh not only is the potassium current augmented but also the slow inward current of calcium is reduced3. It is not clear how the c…
Modulation of NMDA receptor function by cyclic AMP in cerebellar neurones in culture
2004
The signal transduction pathways involved in NMDA receptor modulation by other receptors remain unclear. cAMP could be involved in this modulation. The aim of this work was to analyse the contribution of cAMP to NMDA receptor modulation in cerebellar neurones in culture. Forskolin increases cAMP and results in increased intracellular calcium and cGMP that are prevented by blocking NMDA receptors. Similar effects were induced by two cAMP analogues, indicating that cAMP leads to NMDA receptor activation. It has been reported that phosphorylation of Ser897 of the NR1 subunit of NMDA receptors by cAMP-dependent protein kinase (PKA) activates the receptors. Forskolin increases Ser897 phosphoryla…
Non invasive blood flow measurement in cerebellum detects minimal hepatic encephalopathy earlier than psychometric tests
2013
AIM: To assess whether non invasive blood flow measurement by arterial spin labeling in several brain regions detects minimal hepatic encephalopathy. METHODS: Blood flow (BF) was analyzed by arterial spin labeling (ASL) in different brain areas of 14 controls, 24 cirrhotic patients without and 16 cirrhotic patients with minimal hepatic encephalopathy (MHE). Images were collected using a 3 Tesla MR scanner (Achieva 3T-TX, Philips, Netherlands). Pulsed ASL was performed. Patients showing MHE were detected using the battery Psychometric Hepatic Encephalopathy Score (PHES) consisting of five tests. Different cognitive and motor functions were also assessed: alterations in selective attention we…
A Multiomics Study To Unravel the Effects of Developmental Exposure to Endosulfan in Rats: Molecular Explanation for Sex-Dependent Effects
2019
Exposure to low levels of environmental contaminants, including pesticides, induces neurodevelopmental toxicity. Environmental and food contaminants can reach the brain of the fetus, affecting brain development and leading to neurological dysfunction. The pesticide endosulfan is a persistent pollutant, and significant levels still remain detectable in the environment although its use is banned in some countries. In rats, endosulfan exposure during brain development alters motor activity, coordination, learning, and memory, even several months after uptake, and does so in a sex-dependent way. However, the molecular mechanisms driving these effects have not been studied in detail. In this wor…
The visual orientation memory of Drosophila requires Foraging (PKG) upstream of Ignorant (RSK2) in ring neurons of the central complex
2012
Orientation and navigation in a complex environment requires path planning and recall to exert goal-driven behavior. Walking Drosophila flies possess a visual orientation memory for attractive targets which is localized in the central complex of the adult brain. Here we show that this type of working memory requires the cGMP-dependent protein kinase encoded by the foraging gene in just one type of ellipsoid-body ring neurons. Moreover, genetic and epistatic interaction studies provide evidence that Foraging functions upstream of the Ignorant Ribosomal-S6 Kinase 2, thus revealing a novel neuronal signaling pathway necessary for this type of memory in Drosophila.
Heme oxygenase-1: a novel key player in the development of tolerance in response to organic nitrates.
2007
Objective— Nitrate tolerance is likely attributable to an increased production of reactive oxygen species (ROS) leading to an inhibition of the mitochondrial aldehyde dehydrogenase (ALDH-2), representing the nitroglycerin (GTN) and pentaerythrityl tetranitrate (PETN) bioactivating enzyme, and to impaired nitric oxide bioactivity and signaling. We tested whether differences in their capacity to induce heme oxygenase-1 (HO-1) might explain why PETN and not GTN therapy is devoid of nitrate and cross-tolerance. Methods and Results— Wistar rats were treated with PETN or GTN (10.5 or 6.6 μg/kg/min for 4 days). In contrast to GTN, PETN did not induce nitrate tolerance or cross-tolerance as assess…
Sulfhydryl G Proteins and Phospholipase A2-Associated G Proteins Are Involved in Adrenergic Signal Transduction in the Rat Pineal Gland
2001
The rat pineal gland with its circadian noradrenaline-regulated melatonin rhythm is an excellent model for studying adrenergic signal transduction with respect to cAMP and cGMP formation. The stimulatory G(s) proteins play a well-established role in this process. In contrast, the potential roles of the inhibitory G(i) proteins, the functionally unclear other G(o) proteins, and a number of G protein subtypes are not known. The present study examines the effects on beta(1)- and beta(1)-plus-alpha(1)-stimulated cAMP and cGMP formation of a number of G protein modulators in rat pinealocyte suspension cultures. The effects of the nitric oxide donor sodium nitroprusside on cGMP were also examined…
Nitric oxide induces muscular relaxation via cyclic GMP-dependent and -independent mechanisms in the longitudinal muscle of the mouse duodenum
2003
The aim of this study was to investigate, in mouse duodenum, the role of nitric oxide (NO) in the relaxation of longitudinal muscle evoked by nerve activation and the coupled action mechanism. Electrical field stimulation (EFS; 0.5ms, 10-s train duration, supramaximal voltage, at various frequencies) under nonadrenergic noncholinergic conditions evoked muscular relaxation occasionally followed, at the higher stimulus frequencies, by rebound contractions. Inhibition of the synthesis of NO by Nω-nitro-L-arginine methyl ester (L-NAME; 100μM) virtually abolished the evoked relaxation. The relaxation was reduced also by apamin (0.1μM) and by 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ; 1μM)…
In rat pinealocytes the cyclic GMP response to NO is regulated by Ca2+ and protein kinase C
1995
There is ample evidence that beta-adrenergic stimulation of cyclic GMP formation is potentiated by alpha1-adrenergic mechanisms, the latter leading to elevation of intracellular Ca2+ concentration ([Ca2+]i) and protein kinase C (PKC) activation. Recent studies have shown that nitric oxide synthase (NOS) and nitric oxide (NO) are a component of the adrenoceptor-cyclic GMP signalling pathway. The aim of the present investigation was to study the roles of alpha1-adrenergic mechanisms, Ca2+ and PKC on NO-stimulated cyclic GMP formation. To this end suspension cultures of rat pinealocytes were treated with the NO donor sodium nitroprusside (SNP) in the presence of alpha1-adrenergic agonists, [Ca…