Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.4.1 (phosphodiesterase)
 18,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Using rat hepatocytes we confirmed our previous results that glucagon and beta-adrenergic agonists increased the enzyme activity of alanine aminotransferase (AAT) and propranolol abolished their effects. Only the enzyme activity was measured and other parameters like quantity of the enzyme or activation due to modification were not looked for. As in perfusion experiment phenylephrine and phenoxybenzamine (alpha-agonist and alpha-antagonist respectively) also alpha-antagonist respectively) also increased the AAT activity in isolated rat hepatocytes and propranolol reversed these effects. The additive effect of glucagon and phenoxybenzamine on AAT was also persistent in hepatocyte system. Fructose-1:6-bisphosphatase (Fru-P2-ase), another key enzyme in gluconeogenic pathway, was elevated by glucagon and other beta-adrenergic agonists both in liver perfusion and isolated hepatocyte experiments and was brought back to the normal level by propranolol. In this case also only the enzyme activity was measured and no other parameters were looked for. Unlike AAT this enzyme was not stimulated by phenylephrine or phenoxybenzamine. But AAT and Fru-P2-ase activities were increased significantly by adenylate cyclase activators like fluoride or forskolin. Thus, it appears that the regulation of fru-P2-ase by glucagon is purely a b-receptor mediated process whereas AAT activation shows a mixed type of regulation where some well known alpha-agonist and antagonists are behaving as beta-agonists. Results further indicate the presence of phosphodiesterase in hepatocyte membrane which was stimulated by glucagon and brought back to the normal level by propranolol. The different adrenergic compounds stated above, not only modified the activity of the above two enzymes but also stimulated glucose production by hepatocytes from alanine which was in turn abolished by propranolol as well as amino oxyacetate (AOA), a highly specified inhibitor of AAT. This confirm the participation of AAT in gluconeogenesis from alanine in liver. Forskolin and fluoride also increased the glucose production from alanine and showed additive effects with glucagon, phenylephrine and phenoxybenzamine.
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PMID:Effect of adrenergic agonists and antagonists on alanine amino transferase, fructose-1:6-bisphosphatase and glucose production in hepatocytes. 135 93

Actinomyces viscosus T14V, a Gram-positive bacterium found in the oral cavity, was found to be insensitive to glucose-mediated catabolite repression. Basal levels of beta-galactosidase (18-26 U) were observed at all phases of growth regardless of the culture conditions. Further, beta-galactosidase could not be induced with lactose, or with a known inducer of the enzyme, isopropyl-beta-D-thiogalactoside, or with dibutyryl cAMP. Glucose, on the other hand, stimulated cAMP accumulation in a concentration-dependent manner. Fructose and sucrose mimicked the effects of glucose on cAMP accumulation, whereas galactose, mannose and maltose had lesser stimulatory effects. Other carbon sources, i.e., lactose, alpha-methylglucoside, ribose, xylose and succinate were without effect. Glucose and alpha-methylglucoside were found to stimulate cAMP accumulation in toluene-permeabilized cells, in the presence of the phosphodiesterase inhibitor, theophylline. Glucose did not stimulate cAMP levels in other Gram-positive bacteria including Streptococcus mutans, S. sanguis and S. salivarius but did cause cAMP accumulation in other strains of A. viscosus. The results suggest that glucose effects on cAMP metabolism are independent of the induction of beta-galactosidase as presently defined for Escherichia coli, and that the effects appear to be selective to the A. viscosus bacteria. The results also suggest that glucose stimulates cAMP accumulation via activation of adenylate cyclase.
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PMID:Glucose stimulates cAMP accumulation in the oral bacterium Actinomyces viscosus. 839 89

Intestinal fructose transporter (GLUT5) expression normally increases significantly after completion of weaning in neonatal rats. Increases in GLUT5 mRNA, protein, and activity can be induced in early weaning pups by precocious consumption of dietary fructose or by perfusion of the small intestine with fructose solutions. Little is known about the signal transduction pathway of the dietary fructose-mediated increase in GLUT5 expression during early intestinal development. Recent microarray results indicate that key gluconeogenic enzymes modulated by cAMP are markedly upregulated by fructose perfusion; hence, we tested the hypothesis that cAMP plays an important role in regulating intestinal fructose absorption by simultaneously perfusing adenylyl cyclase, phosphodiesterase, or protein kinase A (PKA) inhibitors along with fructose. Intestinal fructose uptake rates increased by 100% in rat pups perfused with 8-bromo-cAMP. Simultaneous fructose and dideoxyadenosine (DDA; inhibitor of adenylyl cyclase) perfusion completely inhibited increases in fructose uptake rate induced by perfusion with fructose alone. Fructose perfusion increased intestinal mucosal cAMP concentrations by 27%, but simultaneous perfusion of fructose and DDA inhibited the fructose-induced increase in cAMP. However, GLUT5 and sodium-glucose cotransporter (SGLT1) mRNA abundance and glucose transport rates were each not significantly affected by 8-bromo-cAMP and DDA. Moreover, simultaneous perfusion of the small intestine with fructose and PKA inhibitor or N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamid. 2HCl, both inhibitors of PKA, did not prevent the fructose-induced increases in GLUT5 mRNA abundance and fructose uptake rate. Cyclic AMP appears to modulate fructose transport without affecting GLUT5 mRNA abundance, and without involving PKA.
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PMID:Cyclic AMP stimulates fructose transport in neonatal rat small intestine. 1522 56