Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.5.4.17 (adenosine deaminase)
5,206 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Adenosine deaminase and adenosine deaminase complexing protein have been localized in rabbit brain. Brains fixed in paraformaldehyde or in Clarke's solution were blocked coronally. Blocks from brains fixed in paraformaldehyde were either frozen in liquid nitrogen or embedded in paraffin. Tissue fixed in Clarke's solution was embedded in paraffin. Sections from each block were stained by the peroxidase-antiperoxidase method for adenosine deaminase or complexing protein using affinity-purified goat antibodies. Adenosine deaminase and complexing protein did not co-localize. Adenosine deaminase was detected in oligodendroglia and in endothelial cells lining blood vessels, whereas complexing protein was concentrated in neurons. The subcellular location and appearance of the peroxidase reaction product associated with individual cells was also quite distinctive. The cell bodies of adenosine deaminase-positive oligodendroglia were filled with intense deposits of peroxidase reaction product. In contrast to oligodendroglia, the reaction product associated with most neurons stained for complexing protein was concentrated in granular-appearing cytoplasmic deposits. In some instances, these deposits were clustered about the nuclear membrane. Staining of neurons in the granular layer of cerebellum was an exception. Granule cells were lightly outlined by peroxidase reaction product. Cerebellar islands, also referred to as glomeruli, were stained an intense uniform brown. These results raise the possibility that oligodendroglia and blood vessel endothelia, through the action of adenosine deaminase, might play a role in controlling the concentration of extracellular adenosine in brain. They do not, however, support the suggestion that complexing protein aids in adenosine metabolism by positioning adenosine deaminase on the plasma membrane.
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PMID:Localization of adenosine deaminase and adenosine deaminase complexing protein in rabbit brain. 354 89

The importance of endogenous myocardial adenosine in attenuating catecholamine-elicited contractile responses was investigated in perfused oxygenated rat hearts. Perfusion of the isolated hearts with adenosine deaminase potentiated the isoproterenol-induced increases of three contractile variables (left ventricular pressure development and rates of both left ventricular pressure development and relaxation). The peak (maximal, within 30 s) and maintained (after 1 min) increases of the contractile variables caused by 10(-8) M isoproterenol were enhanced by 15-22 and 31-43%, respectively. Adenosine deaminase appeared in epicardial surface transudates of similarly perfused hearts, indicating that the enzyme had entered the myocardial interstitial space. Isoproterenol alone elevated the release of adenosine into coronary effluents of isoproterenol-stimulated hearts, and adenosine deaminase prevented the release of the nucleoside. The higher the level of adenosine in the effluent, the greater the reduction of the peak contractile variables. Phenylisopropyladenosine at 10(-8) M prevented the adenosine deaminase potentiation of 10(-9) M isoproterenol-induced contractile responses. The adenosine analogue at 10(-6) M blocked completely the isoproterenol-produced increases in the contractile variables. These results suggest that endogenous adenosine prevents full mechanical responsiveness to beta-adrenoceptor stimulation in the oxygenated myocardium. In addition, the findings support the notion that adenosine serves as an important negative feedback modulator in the oxygenated heart.
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PMID:Endogenous adenosine inhibits catecholamine contractile responses in normoxic hearts. 374 Feb 98

We studied the activity of adenosine deaminase in the peritoneal fluid of 66 patients who were divided into five groups according to causes of ascites as follows: tuberculous peritonitis (group I), septic peritonitis (group II), secondary to malignant tumours (group III), miscellaneous conditions (group IV), and control subjects of transudates (group V). In patients with tuberculous peritonitis the enzyme activity was significantly higher than for the rest of the groups (p less than 0.001), and enzyme concentrations in all patients were well above the upper non-tuberculous value. Adenosine deaminase activity in the peritoneal fluid has proved to be a simple and reliable method for early diagnosis of tuberculous peritonitis.
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PMID:Adenosine deaminase activity in the diagnosis of tuberculous peritonitis. 375 18

Adenosine as well as hypoxia and ischemia are known to cause atrioventricular conduction block. To test the hypothesis that adenosine is the primary mediator of hypoxia-induced atrioventricular conduction delay in isolated perfused guinea pig hearts, we characterized a) the time courses of hypoxia-induced adenosine release and delay in atrioventricular conduction, b) the relationships between oxygen tension, adenosine concentration in the effluent, and atria-to-His-bundle interval, and c) the adenosine receptor mediating the negative dromotropic effect of hypoxia. Oxygen tension and effluent adenosine levels were linearly related with a correlation coefficient (r) of -0.85 and a slope of -6.3 +/- 0.37 pmol/min/g/torr. Likewise, oxygen tension and atria-to-His-bundle interval prolongation were linearly related with r = -0.85 and a slope of -0.180 +/- 0.013 msec/torr. The EC50 of effluent adenosine in causing atria-to-His-bundle prolongation was 0.26 +/- 0.02 microM. Adenosine deaminase, an enzyme that deaminates adenosine to inosine and is limited to the extracellular space, significantly attenuated (61%) the atria-to-His-bundle interval prolongation caused by hypoxia. This prolongation was further reduced (81%) by a combination of adenosine deaminase and theophylline, an adenosine receptor blocker. Adenosine deaminase also reduced (by 95%) the atria-to-His-bundle interval prolongation in normoxic recipient hearts caused by the effluent of hypoxic donor hearts. Several adenosine antagonists, i.e., theophylline, 8-phenyltheophylline, and 8-(p-sulfophenyl)theophylline antagonized in a dose-dependent manner the negative dromotropic effect of exogenous adenosine and hypoxia. Schild analysis of the antagonism of hypoxia-induced atria-to-His-bundle interval prolongation by 8-(p-sulfophenyl)theophylline yielded the following pA2 values: 5.30 +/- 0.25 and 5.28 +/- 0.31 using oxygen tension and effluent adenosine vs. AH interval prolongation, respectively. 8-(p-Sulfophenyl)theophylline also antagonized to an equal extent atria-to-His-bundle interval prolongations of similar magnitude caused either by adenosine or hypoxia. We conclude that 1) adenosine is the primary mediator of hypoxia-induced atrioventricular conduction delay, and 2) the adenosine receptor that mediates the negative dromotropic effect of hypoxia is similar to that of exogenous adenosine.
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PMID:Effect of adenosine on atrioventricular conduction. II: Modulation of atrioventricular node transmission by adenosine in hypoxic isolated guinea pig hearts. 379 84

Adenosine deaminase (1 unit/ml) potentiated the lipolytic action of noradrenaline in adipocytes isolated from brown adipose tissue of 1- and 6-week-old rats by decreasing the EC50 (concn. giving 50% of maximal effect) for noradrenaline by 3-4-fold. With cells from neonatal rabbit tissue, adenosine deaminase only had a small, non-significant, effect on the EC50 for noradrenaline. Lipolysis in rat brown adipocytes was inhibited by low concentrations of N6-phenylisopropyladenosine (PIA). Rabbit cells were far less sensitive to PIA. PIA, prostaglandin E1 and nicotinate all inhibited noradrenaline-stimulated respiration in rat brown adipocytes. Hypothyroidism diminished the maximum response of respiration and lipolysis to noradrenaline in rat cells and increased the EC50 for noradrenaline. Responsiveness of lipolysis to noradrenaline was particularly decreased in hypothyroidism and was partially restored by addition of adenosine deaminase. Lipolysis in cells from hypothyroid rats was more sensitive to the anti-lipolytic action of PIA. Bordetella pertussis toxin increased lipolysis in the presence of PIA, suggesting an involvement of the Ni guanine-nucleotide-binding protein in the control of brown-adipocyte metabolism.
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PMID:Effect of adenosine deaminase, N6-phenylisopropyladenosine and hypothyroidism on the responsiveness of rat brown adipocytes to noradrenaline. 380 Sep 44

Adenosine deaminase activity (ADA) was determined around the clock in human plasma from different groups of subjects: presumably clinically healthy women in Minneapolis, USA; healthy medical students, healthy elderly men and women, and mentally ill patients in Paris, France. In addition to analyses of variance, circadian characteristics were estimated individually and summarized by population-mean cosinor for each group. Technical and sampling considerations are documented: the individualized assessment of a circadian rhythm in adenosine deaminase is feasible in 8 out of 11 series from clinically healthy women covering 24h at 20-min intervals. A circadian population rhythm could be determined for the elderly men and women (p less than 0.05) and tentatively (p = 0.053) for the senile demented patients. A difference in circadian group rhythm characteristics found between the healthy elderly subjects and patients with senile dementia deserves further exploration.
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PMID:Circadian rhythms of adenosine deaminase activity in human erythrocytes: a transverse study on young, elderly and senile demented subjects. 383 80

We employed intracoronary infusion of adenosine deaminase to test the hypothesis that endogenous adenosine contributes to regulation of coronary blood flow following acute reductions in coronary artery pressure. In 16 closed-chest anesthetized dogs, we perfused the left circumflex coronary artery from a pressurized arterial reservoir and measured coronary blood flow following changes in perfusion pressure before and 10 minutes after the start of intracoronary adenosine deaminase, 5 U/min per kg body weight. Parallel studies showed that this dose of enzyme resulted in cardiac lymph adenosine deaminase concentrations of 3.2 +/- 0.4 U/ml. Adenosine deaminase abolished the vasodilator response to intracoronary adenosine, 4 and 8 micrograms, but had no effect on the vasodilator response to intracoronary papaverine, 200 and 300 micrograms, demonstrating enzyme efficacy and specificity. Additional experiments demonstrated that adenosine deaminase reversibly attenuated myocardial reactive hyperemia following 5- and 10-second coronary occlusions by 30% (P less than 0.05), evidence that the infused enzyme effectively degraded endogenous adenosine. However, adenosine deaminase did not alter the time course for coronary autoregulation or the steady state autoregulatory flow response over the pressure range between 125 and 75 mm Hg. Further, adenosine deaminase did not alter steady state coronary flow when perfusion pressure was reduced below the range for effective autoregulation (60-40 mm Hg). Such results show that adenosine is not essential for either coronary autoregulation or for the maintenance of coronary vasodilation when autoregulatory vasodilator reserve is expended.
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PMID:Role of adenosine in coronary blood flow regulation after reductions in perfusion pressure. 397 71

Adenosine increases the activity of tyrosine 3-monooxygenase in intact pheochromocytoma cells. The effect of adenosine is not dependent upon extracellular Ca2+, and is not accompanied by an increase in catecholamine secretion from the cells. Adenosine deaminase decreases the basal activity of tyrosine 3-monooxygenase, and almost completely abolishes the activation of this enzyme by adenosine. In cells treated with adenosine deaminase, 2-chloroadenosine causes a 2- to 5-fold increase in tyrosine 3-monooxygenase activity. 2-Chloroadenosine produces half-maximal activation at a concentration of 0.1 microM, and maximal activation at 10 microM. Incubation of cells with 2-chloroadenosine produces a stable activation of tyrosine 3-monooxygenase, as measured in vitro. Finally, 3-chloroadenosine increases the content of cAMP in pheochromocytoma cells, and increases the incorporation of 3H into cAMP in cells that have been preincubated with [3H]adenine. This rise in cAMP presumably mediates the activation of tyrosine 3-monooxygenase by 2-chloroadenosine. Adenosine appears to be an endogenous regulator of tyrosine 3-monooxygenase activity in pheochromocytoma cells.
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PMID:Activation of tyrosine 3-monooxygenase in pheochromocytoma cells by adenosine. 610 63

A previously isolated mouse Cl-1D derived cell line (B-1/25) overproduces adenosine deaminase (EC 3.5.4.4) by 3200-fold. The present studies were undertaken to determine the molecular basis of this phenomenon. Rabbit reticulocyte lysate and Xenopus oocyte translation studies indicated that the B-1/25 cells also overproduced adenosine deaminase mRNA. Total poly(A+) RNA derived from B-1/25 was used to construct a cDNA library. After prehybridization with excess parental Cl-1D RNA to selectively prehybridize nonamplified sequences, 32P-labeled cDNA probe synthesized from B-1/25 total poly(A+) RNA was used to identify recombinant colonies containing amplified mRNA sequences. Positive clones containing adenosine deaminase gene sequences were identified by blot hybridization analysis and hybridization-selected translation in both rabbit reticulocyte lysate and Xenopus oocyte translation systems. Adenosine deaminase cDNA clones hybridized with three poly(A+) RNA species of 1.5, 1.7, and 5.2 kilobases in length, all of which were overproduced in the B-1/25 cell line. Dot blot hybridization analysis using an adenosine deaminase cDNA clone showed that the elevated adenosine deaminase level in the B-1/25 cells was fully accounted for by an increase in adenosine deaminase gene copy number. The adenosine deaminase cDNA probes and the cell lines with amplified adenosine deaminase genes should prove extremely useful in studying the structure and regulation of the adenosine deaminase gene.
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PMID:Amplification and molecular cloning of murine adenosine deaminase gene sequences. 619 12

The accumulations of radioactive cyclic AMP elicited by adenosine, norepinephrine, and histamine in adenine-labeled vesicular entities of a particulate fraction from guinea pig cerebral cortex are greatly reduced as a result of prolonged preincubation. The presence of adenosine deaminase during preincubations largely prevents the loss of adenosine, norepinephrine and histamine responses. Adenosine deaminase was inactivated by deoxycoformycin prior to stimulation of cyclic AMP accumulation by adenosine or amines. If adenosine deaminase is not inactivated, responses to norepinephrine are not significant and histamine responses are reduced by 50%. Adenosine deaminase cannot restore responsiveness of the cyclic AMP-generating systems. It is proposed that, in particulate fractions of guinea pig cerebral cortex, low levels of adenosine cause a slow loss of receptors and/or coupling of receptors to cyclic AMP-generating systems.
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PMID:Cyclic AMP-generating systems in cell-free preparations from guinea pig cerebral cortex: loss of adenosine and amine responsiveness due to low levels of endogenous adenosine. 625 82


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