A histochemical demonstration of the Na++K+-ATPase activity in the thyroid and the effect of cyclic adenosine monophosphate (c-AMP)

1978 ◽  
Vol 34 (11) ◽  
pp. 1513-1514 ◽  
Author(s):  
Mileva Ivić ◽  
Lj. Klisić
Keyword(s):  
Atpase Activity ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Histochemical Demonstration

scholarly journals THE EFFECT OF SOME FACTORS ON THE HISTOCHEMICAL DEMONSTRATION OF LIVER GLYCOGEN PHOSPHORYLASE ACTIVITY

1972 ◽  
Vol 20 (5) ◽  
pp. 331-335 ◽  
Author(s):  
L.-A. LINDBERG ◽  
A. PALKAMA
Keyword(s):  
Enzyme Activity ◽  
Light Microscope ◽  
Ethylenediaminetetraacetic Acid ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Liver Glycogen ◽  
Inhibitory Effect ◽  
Histochemical Demonstration ◽  
Phosphorylase Activity ◽  
Glycogen Phosphorylase Activity

Existing methods for the histochemical demonstration of liver phosphorylase activity were investigated for possible application to a study of enzyme activity using the electron microscope as well as the light microscope. It was found that lead, in concentrations recommended in the literature, cannot be used as the precipitating agent because of its inhibitory effect on phosphorylase activity. The histochemical method based on the demonstration of enzymatically formed glycogen can be improved by adding ethylenediaminetetraacetic acid to the incubating solution. However, the addition of 3',5'-cyclic adenosine monophosphate is not as effective. It is not necessary to add glycogen to the incubating solution. In our opinion enzyme activity cannot yet be demonstrated electron microscopically by the precipitation of liberated phosphate. This is due to the inhibitory effect of high lead concentrations. Under the light microscope the method based on the demonstration of enzymatically formed glycogen is most reliable.

scholarly journals Mechanism of Na-K-ATPase Inhibition by PGE2 in Intestinal Epithelial Cells

Cells ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 752
Author(s):  
Niraj Nepal ◽  
Subha Arthur ◽  
Jennifer Haynes ◽  
Balasubramanian Palaniappan ◽  
Uma Sundaram
Keyword(s):  
Atpase Activity ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Transport Processes ◽  
Intestinal Epithelial ◽  
Transcriptional Inhibition ◽  
Mechanism Of Inhibition ◽  
Primary Means ◽  
Pka Pathway

The primary means of intestinal absorption of nutrients by villus cells is via Na-dependent nutrient co-transporters located in the brush border membrane (BBM). These secondary active co-transport processes require a favorable transcellular Na gradient that is provided by Na-K-ATPase. In chronic enteritis, malabsorption of essential nutrients is partially due to inhibition of villus Na-K-ATPase activity mediated by specific immune inflammatory mediators that are known to be elevated in the inflamed mucosa. However, how Prostaglandin E2 (PGE2), a specific mediator of nutrient malabsorption in the villus BBM, may mediate the inhibition of Na-K-ATPase is not known. Therefore, this study aimed to determine the effect of PGE2 on Na-K-ATPase in villus cells and define its mechanism of action. In vitro, in IEC-18 cells, PGE2 treatment significantly reduced Na-K-ATPase activity, accompanied by a significant increase in the intracellular levels of cyclic Adenosine Monophosphate (cAMP). The treatment with cAMP analog 8-Bromo-cAMP mimicked the PGE2-mediated effect on Na-K-ATPase activity, while Rp-cAMP (PKA inhibitor) pretreatment reversed the same. The mechanism of inhibition of PGE2 was secondary to a transcriptional reduction in the Na-K-ATPase α1 and β1 subunit genes, which was reversed by the Rp-cAMP pretreatment. Thus, the PGE2-mediated activation of the PKA pathway mediates the transcriptional inhibition of Na-K-ATPase activity in vitro.

Mechanisms of ATP to cAMP Conversion Catalyzed by the Mammalian Adenylyl Cyclase: A Role of Magnesium Coordination Shells and Proton Wires

2019 ◽  
Author(s):  
Bella Grigorenko ◽  
Igor Polyakov ◽  
Alexander Nemukhin
Keyword(s):  
Adenylyl Cyclase ◽  
Bond Cleavage ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Md Simulations ◽  
Coordination Shell ◽  
Energy Profile ◽  
One Step ◽  
Type V

<p>We report a mechanism of adenosine triphosphate (ATP) to cyclic adenosine monophosphate (cAMP) conversion by the mammalian type V adenylyl cyclase revealed in molecular dynamics (MD) and quantum mechanics/molecular mechanics (QM/MM) simulations. We characterize a set of computationally derived enzyme-substrate (ES) structures showing an important role of coordination shells of magnesium ions in the solvent accessible active site. Several stable six-fold coordination shells of Mg<sub>A</sub><sup>2+ </sup>are observed in MD simulations of ES complexes. In the lowest energy ES conformation, the coordination shell of Mg<sub>A</sub><sup>2+ </sup>does not include the O<sub>δ1</sub> atom of the conserved Asp440 residue. Starting from this conformation, a one-step reaction mechanism is characterized which includes proton transfer from the ribose O<sup>3'</sup>H<sup>3' </sup>group in ATP to Asp440 via a shuttling water molecule and P<sup>A</sup>-O<sup>3A</sup> bond cleavage and O<sup>3'</sup>-P<sup>A</sup> bond formation. The energy profile of this route is consistent with the observed reaction kinetics. In a higher energy ES conformation, Mg<sub>A</sub><sup>2+</sup> is bound to the O<sub>δ1</sub>(Asp440) atom as suggested in the relevant crystal structure of the protein with a substrate analog. The computed energy profile initiated by this ES is characterized by higher energy expenses to complete the reaction. Consistently with experimental data, we show that the Asp440Ala mutant of the enzyme should exhibit a reduced but retained activity. All considered reaction pathways include proton wires from the O<sup>3'</sup>H<sup>3' </sup>group via shuttling water molecules. </p>

Polydatin Attenuates Carbachol-induced Contraction of Guinea Pig Gallbladder

2019 ◽  
Vol 18 (1) ◽  
pp. 34-38
Author(s):  
Chen Lei ◽  
Pan Xiang ◽  
Shen Yonggang ◽  
Song Kai ◽  
Zhong Xingguo ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Guinea Pig ◽  
Smooth Muscles ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Cyclic Guanosine Monophosphate ◽  
Guanosine Monophosphate ◽  
Dependent Manner ◽  
Underlying Mechanisms ◽  
Dose Dependent

The aim of this study was to determine whether polydatin, a glucoside of resveratrol isolated from the root of Polygonum cuspidatum, warranted development as a potential therapeutic for ameliorating the pain originating from gallbladder spasm disorders and the underlying mechanisms. Guinea pig gallbladder smooth muscles were treated with polydatin and specific inhibitors to explore the mechanisms underpinning polydatin-induced relaxation of carbachol-precontracted guinea pig gallbladder. Our results shown that polydatin relaxed carbachol-induced contraction in a dose-dependent manner through the nitric oxide/cyclic guanosine monophosphate/protein kinase G and the cyclic adenosine monophosphate/protein kinase A signaling pathways as well as the myosin light chain kinase and potassium channels. Our findings suggested that there was value in further exploring the potential therapeutic use of polydatin in gallbladder spasm disorders.

The Role of Intracellular 35-Cyclic Adenosine Monophosphate (cAMP) in Atherosclerosis

2010 ◽  
Vol 8 (4) ◽  
pp. 464-472 ◽  
Author(s):  
Panayotis Fantidis
Keyword(s):  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate

Mapping the Heart

2010 ◽  
Vol 18 (4) ◽  
pp. 6-8
Author(s):  
Stephen W. Carmichael
Keyword(s):  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
G Protein Coupled Receptors ◽  
Receptor Subtypes ◽  
Cardiac Muscle Cells ◽  
Guanine Nucleotide Binding Protein ◽  
The Common ◽  
Guanine Nucleotide Binding ◽  
First Time ◽  
G Protein Coupled

Some of the receptors on the surface of cardiac muscle cells (cardiomyocytes) mediate the response of these cells to catecholamines by causing the production of the common second messenger cyclic adenosine monophosphate (cAMP). An example of such receptors are the β1- and β2-adrenergic receptors (βARs) that are heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptors. Selective stimulation of these two receptor subtypes leads to distinct physiological and pathophysiological responses, but their precise location on the surface of cardiomyocytes has not been correlated with these responses. In an ingenious combination of techniques, Viacheslav Nikolaev, Alexey Moshkov, Alexander Lyon, Michele Miragoli, Pavel Novak, Helen Paur, Martin Lohse, Yuri Korchev, Sian Harding, and Julia Gorelik have mapped the function of these receptors for the first time.

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