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:3.1.4.1 (phosphodiesterase)
18,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The level of phosphodiesterase (PDE) activity is lower in collagenase-isolated human fat cells than in adipose tissue fragments. The inhibition is not species-specific since collagenase also inhibits PDE in rat adipose tissue and bovine heart. In subcellular fractions from isolated fat cells, the PDE activities were lowest in the plasma membrane-enriched fractions and highest in the cytosolic fractions. This is opposite to PDE in subcellular fractions obtained from adipose tissue fragments. In dose-response experiments, collagenase inhibited particulate PDE to a much larger extent than it inhibited soluble PDE. The extracellular activities of PDE were completely eliminated by collagenase. Repeated washings or reincubation of the isolated fat cells did not restore the PDE activity. A purified collagenase with low specific protease activity reduced the PDE activity in isolated fat cells to a lesser extent than did a collagenase with high specific protease activities. Collagen and several protease inhibitors were ineffective in preventing the reduction of PDE after exposure to collagenase. It is concluded that nonspecific proteases in the collagenase preparations used for fat cell isolation interact with particulate and soluble PDE causing an irreversible inhibition of PDE activity in isolated fat cells. Of the various forms of PDE, plasma membrane-associated PDE seems most sensitive to collagenase.
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PMID:Nature of the inhibitory effect of collagenase on phosphodiesterase activity. 299 28

The effects of phosphodiesterase inhibitors and forskolin on steroid-induced germinal vesicle breakdown (GVBD) were investigated in brook trout (Salvelinus fontinalis) oocytes using an in vitro incubation technique. Follicles were first treated with a collagenase solution to remove the follicle wall. Denuded oocytes were examined, using scanning electron microscopy. In all experiments GVBD was induced by the use of 17 alpha, 20 beta-dihydroxy-4-pregnen-3-one. Cyclic adenosine 3',5'-monophosphate (cAMP) levels were measured (by protein-binding assay) in control and forskolin-treated oocytes. Collagenase treatment removed a majority of the follicle wall, as shown by scanning electron microscopy. Partially denuded (PD) oocytes were slightly more sensitive to steroid treatment than intact follicles (IF), as shown by ED50 values; but PD oocytes did not respond to gonadotropin (GTH) stimulation. Both 3-isobutyl-1-methyl-xanthine (IBMX) and SQ20,006 (Squibb) blocked GVBD, but IBMX was more inhibitory. Forskolin also blocked steroid-induced GVBD. Kinetics of inhibition studies were performed using IBMX, forskolin, and cycloheximide. IBMX and cycloheximide inhibited GVBD if added during the first 18 h following steroid stimulation, whereas forskolin blocked GVBD if added within 12 h after steroid treatment. Forskolin, at levels that block GVBD in vitro, significantly increased cAMP in both IF and PD oocytes, but the response of IF was greater than that of PD oocytes.
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PMID:Steroid-induced final maturation in brook trout (Salvelinus fontinalis) oocytes in vitro: the effects of forskolin and phosphodiesterase inhibitors. 304 Jan 36

FSH bioactivity was measured by means of FSH-dependent aromatase activity (conversion of androgen substrate to estradiol). Assay sensitivity was optimized by the use of immature (7-10 days old) rats as Sertoli cell donors, serum-free medium for incubation, phosphodiesterase inhibitor (methylisobutylxanthinine), serial dilution of FSH in medium containing 1% BSA, delayed addition of FSH for 72 h after cell plating, and 19-hydroxyandrostenedione (2.5 X 10(-6) M) as the aromatizable androgen substrate. The method consisted of subjecting the decapsulated immature rat testes to a 2-step collagenase dispersion, plating the cells in medium [Dulbecco's Modified Eagle's Medium-Ham's F-10 (1:1)] containing growth factors and methylisobutylxanthinine for 72 h, adding increasing doses of FSH to the standard curve or small volumes of serum to the test vials as well as 19-hydroxyandrostenedione for 24 h, and measuring estradiol by RIA in dilutions of the medium. Using NIAMDD human (h) FSH-2 as the bioassay standard, the useful range of the assay was 0.01-5.0 ng/ml. Specificity was determined by the addition of graded doses of hLH, hTSH, ACTH, hGH, hPRL, and hCG. The minor degree of FSH bioactivity observed in a few hormone preparations was accounted for by the degree of FSH contamination in them. Mean intra- and interassay coefficients of variation were 9% and 11%, and the index of precision was 0.049. This bioassay was used to determine the bioactive FSH content of pituitary extracts, tissue culture media, elutions from columns, and isoelectrically focused samples. More importantly, small quantities of human sera gave responses parallel to the standard curve in a minimum of two dilutions. The bio- to immunoreactive ratios, expressed as the mean +/- SEM (NIAMDD-hFSH-2), were 0.66 +/- 0.2 in boys (n = 6), 0.78 +/- 0.2 in pubertal girls (n = 6), 1.18 +/- 0.2 in men (n = 13), 1.24 +/- 0.1 in postmenopausal women (n = 30), 1.94 +/- 0.3 in the follicular phase (n = 19), 6.2 +/- 1.4 in the ovulatory phase (n = 19), and 1.6 +/- 0.4 in the luteal phase (n = 19) of the normal menstrual cycle. These results indicate that the bio- to immunoreactive hFSH ratio in the circulation, is dependent upon the hormonal milieu of the subject.
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PMID:An improved in vitro bioassay for follicle-stimulating hormone (FSH): suitable for measurement of FSH in unextracted human serum. 311 17

Mucosal cells of the chicken proventriculus were isolated by a collagenase perfusion method and O2 uptake by the isolated cells was measured as an index of the activity of gastric acid secretion. Oxygen consumption was enhanced by histamine; this effect was augmented by the coexistence of isobutylmethylxanthine, an inhibitor of cyclic adenosine 5.-monophosphate (AMP) phosphodiesterase, and suppressed by imidazole, an activator of the enzyme. The action of histamine was inhibited by cimetidine, an antagonist of the histamine H2 receptor. These results indicate that the isolated cells retained the capacity to take up O2, responding to histamine via the H2 receptor and probably the cyclic AMP level. Gizzerosine (2-amino-9-(4-imidazolyl)-7-azanonanoic acid) also stimulated O2 consumption by the isolated cells. The effect of gizzerosine was cancelled by cimetidine, suggesting that the mechanism by which gizzerosine acts on the mucosal cells is similar to that of histamine action. These observations are consistent with our previous presumption that gizzerosine causes gizzard erosion by enhancing gastric acid secretion in chickens.
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PMID:Effect of gizzerosine on acid secretion by isolated mucosal cells of chicken proventriculus. 360 68

Pancreatic islets of neonatal were dissociated by collagenase and cultured for 3 days in the presence of Cytodex beads to allow attachment of the cells to these microcarriers. The bead-attached cells were packed in columns and superfused with a low bicarbonate medium using the same method that we had originally developed for dissociated anterior pituitary cells of the rat. The secretion of insulin, somatostatin, and glucagon by the cells was monitored by radioimmunoassays. The cells in the superfusion system responded as expected from experiments with islet and monolayer cultures of rat pancreas in vitro and in vivo. Increasing glucose concentrations in the superfusion medium increased the release of insulin and somatostatin (SS), whereas glucagon secretory rates remained constant or decreased. A dose-response curve was established between insulin release and D-glucose in which the ED50 of D-glucose for insulin was found between 1.5 and 2 mg/ml. The phosphodiesterase inhibitor, 3-isobutyl-methylxanthine (IBMX), significantly potentiated the insulin response to glucose. Various secretagogues such as IBMX, 8-bromo cyclic AMP, and L-arginine increased insulin, somatostatin, and glucagon secretory rates in an expected manner. The superfusion method offers the possibility to investigate the interactions of dissociated A-, B-, and D-cells and the dynamics of hormone release in short- and long-term in vitro experiments. The method is simple and avoids the problems of monolayer procedures, such as clustering of the cells and poor adherence of dissociated pancreatic islet cells to dishes.
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PMID:Superfusion of dissociated pancreatic islet cells attached to Cytodex beads. 613 17

Primary culture of bovine adrenal subcapsular cells was used to investigate direct effects of catecholamines on aldosterone secretion. Cells dispersed with collagenase and DNAse and cultured at high density (1.5-2 million/ml) for 3 days displayed high sensitivity to angiotensin II and ACTH, with an ED50 of 1.4 and 1.5 nM, respectively. Adrenergic agonists elicited a 4- to 6-fold stimulation of aldosterone secretion with potency order (-)isoproterenol greater than (-)epinephrine equals (-)norepinephrine greater than (+)isoproterenol, and corresponding ED50 5, 240, 213, and 3000 nM, respectively. No reproducible inhibition by dopamine of basal or stimulated levels of aldosterone secretion could be detected, but a weak stimulatory effect was sometimes observed at high concentration greater than 10 microM. (-)Isoproterenol stimulation of aldosterone production was potently inhibited by the beta-adrenergic antagonists (-)alprenolol and (+)alprenolol with potencies of 1.8 and 110 nM, respectively. The alpha-adrenergic antagonists prazosin, yohimbine, and phentolamine only weakly inhibited (-)isoproterenol stimulation with potencies of 5, 13, and 140 microM, respectively. The potent beta 2-adrenergic antagonist ICI 118.551 and the weaker beta 1-adrenergic antagonist atenolol were roughly equipotent with potencies of 0.27 and 0.44 microM, respectively. Addition of the phosphodiesterase inhibitor Ro 20-1724 at 10 microM doubled the maximum stimulation effect of (-)isoproterenol without changing the potency of the catecholamine or the basal level of aldosterone secretion, suggesting a potential role of cAMP as a mediator of isoproterenol stimulation. These results indicate the presence of a beta 1-adrenergic receptor stimulating aldosterone secretion in bovine zona glomerulosa cells. The physiological significance of direct beta-adrenergic stimulation of aldosterone production is currently being assessed.
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PMID:Direct beta-adrenergic stimulation of aldosterone secretion in cultured bovine adrenal subcapsular cells. 614 9

Short-term (4 h) incubation of collagenase-dispersed Leydig cells from adult rats in the presence of an LHRH agonist caused a 2-3-fold stimulation (P less than 0.001) of testosterone production. This effect was dose-dependent and as little as 5 x 10(-11) M LHRH agonist caused significant stimulation whilst maximal effects were achieved with 10(-9) M concentrations. Stimulation of steroidogenesis by LHRH agonist was prevented by addition of an antiserum specific for the peptide, but was exaggerated in the presence of the phosphodiesterase inhibitor MIX, suggesting the involvement of cyclic AMP in the response of the Leydig cells to the agonist. Native LHRH caused a similar degree of stimulation of testosterone secretion to LHRH agonist but concentrations 1000 times greater than those of the agonist were required to achieve this, a finding consistent with the known affinities of these 2 peptides for the Leydig cell LHRH-receptor. The addition of LHRH agonist also enhanced (P less than 0.001) testosterone secretion by adult rat Leydig cells in response to hCG or dibutyryl cyclic AMP, and this effect was still evident in the presence of maximally-stimulating concentrations of these factors. LHRH agonist also stimulated testosterone secretion by Leydig cells from immature rats, but this effect differed from that in the adult in being of smaller magnitude and being restricted to effects on basal secretion or secretion elicited by low concentrations of hCG. These results show for the first time (a) that LHRH and its agonists can exert effects on Leydig cell steroidogenesis during short-term incubation, and (b) that these effects are stimulatory, which contrasts with the inhibitory effects reported after long-term (2-3 days) exposure of Leydig cells to LHRH agonists in vivo and in vitro. The availability of this simple and rapid measure of a biological action of LHRH on the Leydig cell should enable its precise mode of action to be determined, and should throw light on the physiological role of endogenously produced testicular 'LHRH'.
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PMID:Stimulatory effect of LHRH and its agonists on Leydig cell steroidogenesis in vitro. 617 69

ATP pyrophosphohydrolase was partially purified from fetal bovine epiphyseal cartilage. The purification was about 10- and 100-fold over the enzyme activities of matrix vesicle fraction and cell homogenate, respectively. The pyrophosphohydrolase and alkaline phosphatase were separated by a sequential application of Sepharose CL-6B and DEAE-cellulose column chromatographies. The purified enzyme migrated as a single band corresponding to the molecular weight of 230,000 in sodium dodecyl sulfate-polyacrylamide disc gel by electrophoresis. The enzyme absolutely required Zn2+ for its activity and appeared to bind Zn2+ strongly with an apparent affinity of p[Zn2+]0.5 = 13.4. The apparent Km for ATP was 0.18 mM. The enzyme was also reactive toward various nucleoside triphosphates including GTP, CTP, and UTP. In contrast, various phosphodiesters including RNA, UDP-glucose, NAD, and bis-p-nitrophenylphosphate were 5% or less as reactive as the nucleoside triphosphates. The pyrophosphohydrolase was inactive toward adenosine 3':5'-monophosphate or various phosphonates. UDP-glucose (1 mM), NAD (1 mM), or RNA (1 mg/ml) failed to inhibit the ATP pyrophosphohydrolase activity. These observations suggest that the ATP pyrophosphohydrolase of the cartilage is probably not a phosphodiesterase I. The matrix vesicle fraction, which probably also included some plasma membrane vesiculated during collagenase digestion, contained the highest specific activity of the enzyme as compared to other subcellular fractions of either epiphyseal or articular cartilage.
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PMID:Purification and partial characterization of ATP pyrophosphohydrolase from fetal bovine epiphyseal cartilage. 621 90

Capillaries isolated by collagenase digestion of hamster epididymal fat pads were used to examine the properties of endothelial adenylate cyclase and cyclic nucleotide phosphodiesterase. Adenylate cyclase activity in capillary homogenates was increased by 10 microM GTP or 100 microM isoproterenol. Lower concentrations of the catecholamine and 5.7 microM prostaglandin E1 did not stimulate endothelial adenylate cyclase activity unless GTP was included in the assay system. The effects of isoproterenol on capillary adenylate cyclase activity were blocked by propranolol, but were not affected by phentolamine. Phosphodiesterase activity in endothelial homogenates showed anomalous kinetic behavior with either cyclic AMP or cyclic GMP as the enzyme substrate. At substrate concentrations below 1 microM, capillary phosphodiesterase activity hydrolyzed cyclic GMP 2-6 times faster than cyclic AMP. However, at high substrate levels, e.g., 100 microM, cyclic AMP and cyclic GMP were degraded at similar rates. Hydrolysis of 1 microM cyclic AMP by capillary homogenates was stimulated by 0.1 and 1 microM cyclic GMP. Caffeine, 1-methyl-3-isobutylxanthine, papaverine and dipyridamole SQ 20009 were effective inhibitors of capillary phosphodiesterase activity. In contrast, imidazole enhanced the activity of the enzyme. The presence of adenylate cyclase and phosphodiesterase activities in hamster isolated capillaries is consistent with a role for cyclic AMP in the regulation of endothelial function. Moreover, the experiments described here indicate that hamster isolated capillaries are useful model systems for studying the metabolism of vascular endothelium.
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PMID:Properties of adenylate cyclase and cyclic nucleotide phosphodiesterase in hamster isolated capillary preparations. 624 1

The maximum phosphodiesterase activity (Vmax) with low and high Km was, respectively, 10- and 3-times greater in tissue fragments than in collagenase-isolated adipocytes obtained from subcutaneous fat layers in man. The exposure of such tissue fragments to collagenase of various origins in order to isolate the fat cells resulted in a 60-70% inhibition of phosphodiesterase (PDE) activity. Noradrenaline- and isopropyl noradrenaline-induced rates of lipolysis were more rapid in the isolated fat cells than in the tissue fragments. The sensitivity to catecholamines, however, was the same for the two tissue preparations. Nor did they differ in respect to the effect of theophylline, a PDE inhibitor, on the rate of lipolysis. The time curve for cyclic AMP accumulation was significantly higher in the isolated adipocytes than in tissue fragments in the presence of isopropyl noradrenaline. It is concluded that the greater lipolytic response of collagenase-isolated adipocytes than of tissue fragments to catecholamines may be attributed, at least in some measure, to the higher concentration of cyclic AMP resulting from a decrease in PDE activity.
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PMID:Influence of adipocyte isolation by collagenase on phosphodiesterase activity and lipolysis in man. 624 9


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