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Target Concepts:
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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)
In fat cells isolated from the parametrial adipose tissue of rats, the addition of purified
adenosine deaminase
increased lipolysis and cyclic adenosine 3':5'-monophosphate (cyclic AMP) accumulation. Adenosine deaminase markedly potentiated cyclic AMP accumulation due to norepinephrine. The increase in cyclic AMP due to
adenosine deaminase
was as rapid as that of theophylline with near maximal effects seen after only a 20-sec incubation. The increases in cyclic AMP due to crystalline
adenosine deaminase
from intestinal mucosa were seen at concentrations as low as 0.05 mug per ml. Further purification of the crystalline enzyme preparation by Sephadex G-100 chromatography increased both
adenosine deaminase
activity and cyclic AMP accumulation by fat cells. The effects of
adenosine deaminase
on fat cell metabolism were reversed by the addition of low concentrations of N6-(phenylisopropyl)adenosine, an analog of adenosine which is not deaminated. The effects of
adenosine deaminase
on cyclic AMP accumulation were blocked by coformycin which is a potent inhibitor of the enzyme. These findings suggest that deamination of adenosine is responsible for the observed effects of
adenosine deaminase
preparations. Protein kinase activity of fat cell homogenates was unaffected by adenosine or N6-(phenylisopropyl)adenosine. Norepinephrine-activated adenylate cyclase activity of fat cell ghosts was not inhibited by N6-(phenylisopropyl)adenosine. Adenosine deaminase did not alter basal or norepinephrine-activated adenylate cyclase activity.
Cyclic AMP phosphodiesterase
activity of fat cell ghosts was also unaffected by
adenosine deaminase
. Basal and insulin-stimulated glucose oxidation were little affected by
adenosine deaminase
. However, the addition of
adenosine deaminase
to fat cells incubated with 1.5 muM norepinephrine abolished the antilipolytic action of insulin and markedly reduced the increase in glucose oxidation due to insulin. These effects were reversed by N6-(phenylisopropyl)adenosine. Phenylisopropyl adenosine did not affect insulin action during a 1-hour incubation. If fat cells were incubated for 2 hours with phenylisopropyl adenosine prior to the addition of insulin for 1 hour there was a marked potentiation of insulin action. The potentiation of insulin action by prior incubation with phenylisopropyl adenosine was not unique as prostaglandin E1, and nicotinic acid had similar effects.
...
PMID:Effects of adenosine deaminase on cyclic adenosine monophosphate accumulation, lipolysis, and glucose metabolism of fat cells. 16 37
1. Lipolysis has been measured in parametrial adipocytes from virgin, pregnant and lactating rats. 2. The basal rate and the maximal rate of lipolysis, the latter measured in the presence of noradrenaline and theophylline, remained constant between the three experimental categories, with the exception of a significant transient increase in the basal rate at parturition. 3. The noradrenaline-stimulated lipolysis rate rose above the virgin rate during pregnancy and fell below it during lactation; inclusion of
adenosine deaminase
in incubations abolished these differences in response to noradrenaline. 4.
Cyclic AMP phosphodiesterase
activity was lower in adipocytes during pregnancy and lactation than in virgin animals.
...
PMID:Lipolysis in rat adipocytes during pregnancy and lactation. The response to noradrenaline. 628 71
