Phosphatidic acid and phosphatidylinositol labelling in adipose tissue. The role of endogenously formed adenosine
| Autor: | K K McMahon, R J Schimmel, T W Honeyman |
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| Rok vydání: | 1983 |
| Předmět: |
Agonist
History medicine.medical_specialty Adenosine Adenosine Deaminase medicine.drug_class Phospholipid In Vitro Techniques Phosphatidylinositols Clonidine Methoxamine Education chemistry.chemical_compound Adenosine deaminase 1-Methyl-3-isobutylxanthine Cricetinae Internal medicine Isoprenaline medicine Animals Phosphatidylinositol Phospholipids Mesocricetus biology Chemistry Isoproterenol Phosphatidic acid Computer Science Applications Endocrinology Adipose Tissue Biochemistry biology.protein Research Article medicine.drug |
| Zdroj: | Biochemical Journal. 212:499-506 |
| ISSN: | 0306-3283 |
| DOI: | 10.1042/bj2120499 |
| Popis: | Incorporation of [32P]Pi into phosphatidic acid and phosphatidylinositol of hamster epididymal adipocytes was partially inhibited by 3-isobutyl-1-methylxanthine. This effect of 3-isobutyl-1-methylxanthine was antagonized by isopropyl-N6-phenyladenosine but not by 2′,5′-dideoxyadenosine, prostaglandin E1 or clonidine. N6-Phenylisopropyladenosine did not affect incorporation of [32P]Pi into phosphatidic acid or phosphatidylinositol when 3-isobutyl-1-methylxanthine was not present. In contrast with 3-isobutyl-1-methylxanthine inhibition of [32P]Pi incorporation into phospholipids, which was blocked only by N6-phenylisopropyladenosine, accelerated lipolysis was blocked by prostaglandin E1, clonidine and 2′,5′-dideoxyadenosine as well as by N6-phenylisopropyladenosine. Phospholipid labelling was also decreased in the presence of adenosine deaminase, but not in the presence of isoprenaline (isoproterenol). The stimulatory effect of N6-phenylisopropyladenosine on [32P]Pi incorporation into phospholipids in cells exposed to 3-isobutyl-1-methylxanthine was evident as soon as 3 min after addition of the adenosine analogue and maximum 10 min after its addition. As observed by others, [32P]Pi incorporation into phospholipids was increased by the alpha 1-selective agonist methoxamine. The stimulatory effect of methoxamine occurred with a time course similar to that of N6-phenylisopropyladenosine and was present at nearly equal magnitude in the absence or presence of 3-isobutyl-1-methylxanthine. The inhibitory effects of 3-isobutyl-1-methylxanthine and adenosine deaminase on phospholipid labelling are attributed to blockade of the action, or to the enzymic removal, of adenosine formed in and released from the fat-cells during their incubation. Supporting this view is the selective reversal of the actions of 3-isobutyl-1-methylxanthine and of adenosine deaminase by N6-phenylisopropyladenosine. These findings suggest an important role for endogenous adenosine in regulation of phospholipid turnover in adipocytes. |
| Databáze: | OpenAIRE |
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