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 modulation of neuronal adenylylcyclase by Ca2+, acting via calmodulin, is a long-established example of a positive interaction between the Ca2(+)-mobilizing and cAMP-generating systems. In the present study, concentrations of Ca2+ that stimulate brain adenylylcyclase inhibit the adenylylcyclase of NCB-20 plasma membranes. These inhibitory effects of Ca2+ have been characterized and seem to be exerted at the catalytic unit of the enzyme; they are independent of calmodulin, Gi, and phosphodiesterase. To determine whether this inhibition of adenylylcyclase by Ca2+ could occur in the intact cell, cAMP accumulation was measured in response to bradykinin. Bradykinin, which mobilizes Ca2+ in NCB-20 cells, as a consequence of stimulating inositol phosphate production, causes a transient inhibition of prostaglandin E1 stimulation of cAMP accumulation. The inhibitory action of bradykinin is attenuated significantly by treatment of cells with the cell-permeant Ca2+ chelator, 1,2-bis-(2-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid. It seems likely that the inhibition of adenylylcyclase by low concentrations of Ca2+ represents a novel means for a negative interaction between Ca2(+)-mobilizing and cAMP-generating systems.
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PMID:Bradykinin stimulates Ca2+ mobilization in NCB-20 cells leading to direct inhibition of adenylylcyclase. A novel mechanism for inhibition of cAMP production. 184 32

Caffeine was used to study the intracellular Ca2+ pools of bovine chromaffin cells. Its effects on cytosolic Ca2+ concentration ([Ca2+]i) were examined using fura-2. Caffeine caused a transient increase in [Ca2+]i in the presence or absence of extracellular Ca2+. In the former case, the caffeine-induced [Ca2+]i increase was higher and stayed above the basal value for several minutes. In the latter case, the [Ca2+]i rise was lower and fell to the basal level within 1 min. These results suggest that caffeine increases [Ca2+]i by causing both Ca2+ influx and Ca2+ release from intracellular pools. In the absence of extracellular Ca2+, ionomycin but not caffeine caused a further increase in [Ca2+]i in cells that had been treated with caffeine. Apparently there are at least two intracellular Ca2+ pools, only one of which is sensitive to caffeine. The caffeine-induced [Ca2+]i rise became smaller when the cells were pretreated with the inositol trisphosphate-generating agonists, methacholine and bradykinin. In addition, methacholine was unable to initiate a [Ca2+]i transient after the cells had been treated with caffeine. The results indicate that the caffeine-sensitive Ca2+ pools overlap with the inositol trisphosphate-sensitive pool and that the size of the latter pool is smaller than that of the former. The caffeine-sensitive Ca2+ pools were refilled after high K+ treatment, which suggests that the caffeine-sensitive Ca2+ pools may be important in buffering the cytosolic Ca2+. The effect of caffeine on [Ca2+]i is not due to inhibition of phosphodiesterase. Our results support a Ca2+ entry model in which depletion of intracellular Ca2+ pools controls the rate of Ca2+ entry across the plasma membrane.
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PMID:Caffeine-sensitive calcium stores in bovine adrenal chromaffin cells. 189 65

The effect of Cyclosporin A (CsA) on vascular vasomotor responses was determined in two isolated tissue preparations. The first preparation was the rat mesenteric vascular bed which was constricted by phenylephrine (EC80) and perfused with CsA (8.32 x 10(-8) to 8.32 x 10(-6) M). Vasodilation responses to acetylcholine, bradykinin and the calcium ionophore, A23187, were impaired, as was the response to sodium nitroprusside at high CsA concentrations. Indomethacin had no effect suggesting that the CsA effect is unrelated to the synthesis of cyclooxygenase products. In the second preparation, thoracic aortic rings from rats treated with CsA (5-10 and 20-50 mg/kg/daily for 3 and 1 weeks, respectively) were used. Aorta rings precontracted by phenylephrine (EC80) also showed impaired responses to both endothelium-dependent (acetylcholine) and endothelium-independent (sodium nitroprusside) vasodilators. Furthermore, a marked decrease of the guanosine 3',5'-cyclic monophosphate (cGMP) content in aortic preparations was found to accompany the in vivo effect of CsA on relaxation. In addition, exposure of aortic rings to CsA (8.32 x 10(-8) to 8.32 x 10(-6) M) in vitro, also inhibited markedly the cGMP response induced by acetylcholine or sodium nitroprusside. This effect of CsA was not modified by isobutyl methylxanthine, a phosphodiesterase inhibitor. We conclude that CsA acts directly on the vascular smooth muscle; and speculate that CsA may compromise the response to vasodilators by inhibiting cGMP formation.
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PMID:Attenuation of vascular relaxation and cyclic GMP responses by cyclosporin A. 215 99

Bradykinin (10(-6) and 10(-5) M) stimulated ACTH-IR release from rat anterior pituitary tissue in vitro concentration-dependently. The onset of this effect was delayed in comparison to that of AVP or CRF. The combined treatment of bradykinin with AVP or CRF produced additive effects of ACTH-IR release. Bradykinin may represent another candidate involved in the regulation of ACTH release. In contrast to AVP, bradykinin did not stimulate prostaglandin E2 synthesis in the pituitary tissue. Bradykinin-induced ACTH-IR release remained unchanged following cyclooxygenase inhibition by indomethacin. It can be concluded that prostaglandins are not involved in the action of bradykinin on the anterior pituitary. Bradykinin did stimulate cyclic AMP accumulation in pituitary tissue. Inhibition of phosphodiesterase by 3-isobutyl-l-methylxanthine (IBMX) potentiated the ACTH-IR release evoked by bradykinin. From the results obtained, we concluded that cyclic AMP appears to be involved as a second messenger in the bradykinin-evoked ACTH-IR release.
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PMID:Bradykinin-induced ACTH release from rat pituitary tissue in vitro. 242 24

The rat adipocyte contains two separate mechanisms for prostaglandin (PG) production. Norepinephrine stimulates prostacyclin (PGI2) and PGE2 production and triglyceride lipolysis in isolated rat adipocytes. In contrast, the vasoactive peptides angiotensin II, vasopressin, and bradykinin stimulate PGI2 production, but not PGE2 production or triglyceride lipolysis, in these cells. In this study, we characterized the two separate mechanisms of PG production with respect to the time course, the role of cAMP, the identity of the adrenergic receptor, and the effects of insulin and glucocorticoids. Angiotensin II stimulated PGI2 production rapidly (at 5 min) and independently of cAMP. beta-Adrenergic stimulation with isoproterenol produced a rapid 11-fold increase in the cAMP concentration and stimulated PGI2 production more slowly (at 120 min). The phosphodiesterase inhibitor 1-methyl-3-isobutylxanthine (0.2 and 0.5 mM) and the adenylate cyclase activator forskolin (10 microM) also stimulated cAMP production rapidly and PGI2 production more slowly. 1-Methyl-3-isobutylxanthine (5.0 mM) further stimulated cAMP levels, but prevented the increase in PGI2 production and blunted the increase in glycerol release seen at lower concentrations. beta-Adrenergic blockade with propranolol or timolol completely inhibited the norepinephrine- or isoproterenol-stimulated production of PGI2 and triglyceride lipolysis, respectively. Insulin selectively inhibited isoproterenol-stimulated PGI2 production and triglyceride lipolysis at physiological concentrations, but had no effect on angiotensin II-stimulated PGI2 production. In contrast, dexamethasone inhibited PGI2 production induced by both isoproterenol and angiotensin II. We conclude that: angiotensin II stimulates PGI2 production rapidly and independently of cAMP, but isoproterenol stimulates PGI2 production more slowly, an effect that is cAMP dependent; insulin inhibits the cAMP-dependent beta-adrenergic stimulation of PGI2 production (and triglyceride lipolysis), but not the cAMP-independent angiotensin II-induced stimulation of PGI2 production (this suggests that the former effect is mediated by a decrease in cAMP levels in the adipocyte); and dexamethasone inhibits both mechanisms of PGI2 production. Both mechanisms of PGI2 production by rat adipocytes are exquisitely sensitive to hormonal regulation.
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PMID:Prostacyclin production by isolated rat adipocytes: evidence for cyclic adenosine 3',5'-monophosphate-dependent and independent mechanisms and for a selective effect of insulin. 242 31

We know that the mast cell or basophil degranulation and the release of chemical mediators such as histamine may play an important role in inducing immediate type allergic reactions. In this experiment, employing purified rat peritoneal mast cells (RPMC) the degranulation pattern of RPMC and percent release of histamine from RPMC by pharmacologic (compound 48/80, kallikrein or peptidoglycan) or allergic (IgE-anti IgE complex) stimuli were examined. The inhibitory effects of catecholamine (isoproterenol), an adenylate cyclase stimulator, methylxanthine (IBMX: 3-isobutyl-1-methyl-xanthine), a phosphodiesterase inhibitor and chemical mediators (histamine, serotonin, bradykinin) on compound 48/80-induced RPMC degranulation and also those of catecholamine, methylxanthine and chemical mediators on IgE-anti IgE complex-induced histamine release from RPMC were tested. Compound 48/80-induced RPMC degranulation was remarkably inhibited not only by treatment with isoproterenol and IBMX, but also by treatment with histamine. It was not, however, inhibited by serotonin or bradykinin. The inhibitory effect of histamine on compound 48/80-induced RPMC degranulation was blocked by pretreatment with H2-antagonist (cimetidine), but not by H1-antagonist (diphenhydramine). The cyclic adenosine 3',5'-monophosphate (cAMP) content of RPMC was significantly increased by pretreatment with histamine as well as isoproterenol and IBMX. These facts suggest that cAMP acts as a regulator or modulator of the RPMC degranulation and the histamine release from mast cells and that the inhibitory effect induced by histamine may be related to the H2-receptor existing on the surface of mast cells.
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PMID:[Studies on the degranulation and histamine release of purified rat peritoneal mast cells. The inhibitory effect of histamine and other chemicals]. 247 72

Muscarinic receptor stimulation increased the accumulation of 3H-inositol phosphates in PC12 cells whose phospholipids had been prelabeled with [3H]inositol. Muscarine also inhibited the increase in cyclic AMP (cAMP) accumulation caused by 5'-N-ethylcarboxamide adenosine or by vasoactive intestinal peptide. This effect of muscarine was apparently due to the inhibition of adenylate cyclase rather than to a stimulation of a cAMP specific phosphodiesterase. The muscarinic receptor antagonist pirenzepine inhibited both the stimulation of inositol-phospholipid metabolism and the inhibition of cAMP production with Ki values of 0.34 microM and 0.36 microM, respectively. PC12 cells contained a single class of N-[3H]methylscopolamine ([3H]NMS) binding sites. Competition studies with muscarine (KD, 15 microM) and pirenzepine (Ki, 0.12 microM) revealed no evidence for multiple muscarinic receptors. The Ki of pirenzepine for the inhibition of [3H]NMS binding and the inhibition of muscarinic actions is consistent with the possibility that this is not an M1 receptor. Muscarine inhibited cAMP accumulation in cells made deficient in protein kinase C; therefore, this protein kinase is probably not involved in mediating the inhibitory effect of muscarine. The phorbol ester 12-O-tetradecanoylphorbol 13-acetate also inhibited cAMP accumulation in PC12 cells but the mechanism of this effect differed from that of muscarine. Bradykinin caused a large increase in the accumulation of 3H-inositol phosphates and [3H]diacylglycerol relative to muscarine but did not inhibit cAMP production. Oxotremorine inhibited cAMP accumulation but it did not stimulate inositol-phospholipid metabolism.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Muscarinic receptor stimulation increases inositol-phospholipid metabolism and inhibits cyclic AMP accumulation in PC12 cells. 254 58

The intracellular messengers that seem to be involved in renin secretion (RS) from juxtaglomerular cells (JG) are calcium (Ca), cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). Unlike the majority of secretory systems, an increase in intracellular Ca concentration and calmodulin and protein kinase C activation inhibit RS. The intracellular Ca concentration in JG cells can be modified if: 1) the normal mechanisms of Ca extrusion of these cells is altered; 2) the calcium output is blocked by lanthanum; 3) the function of the voltage-sensitive Ca-channels is modified; 4) uptake or liberation of Ca from endoplasmic reticulum is modified; 5) plasmatic membrane is bypassed with calcium ionophores such as A 23187. 6) JG cells are stimulated by hormones that increase Ca and activate protein kinase C such as angiotensin II, vasopressin or alpha-1 adrenergic agonists; 7) extracellular Ca concentration increases or decreases. RS is stimulated by dibutyryl cAMP, cAMP phosphodiesterase inhibitors and by hormones and agents that activate adenylate cyclase (beta adrenergic agonists, bradykinin, histamine, forskolin and ethylcarboxamide adenosine). On the contrary, RS is inhibited by hormones and agents that inhibit adenylate cyclase such as: alpha-2 adrenergic agonists, neuropeptide Y, angiotensin II and cyclohexyladenosine. Pertussis toxin increases basal RS, blocks the inhibition by agents and hormones which inhibit adenylate cyclase and potentiate the stimulation produced by beta-adrenergic agonists. In JG cells, atrial natriuretic peptide inhibits RS, increases cGMP and decreases cAMP. The increase in cGMP correlates well with the inhibition of RS.
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PMID:[Intracellular messengers in the regulation of renin secretion]. 255 Oct 26

To investigate the hypothesis that cyclic AMP (cAMP) regulates arachidonic acid metabolism in vascular tissue, we have studied the effects of forskolin (FSK), an activator of adenylate cyclase, and 3-isobutyl-1-methylxanthine (IBMX), a phosphodiesterase inhibitor, on hormone-stimulated prostacyclin (PGI2) synthesis in porcine aortic endothelial cells grown in culture. In these experiments, bradykinin (1 microgram/ml) and A23187 (0.2 microM) potently stimulated PGI2 biosynthesis (9- and 10-fold respectively). However, prostaglandin synthesis in response to either of these agents was not affected by FSK even though FSK elevated intracellular levels of cAMP 10-fold. IBMX failed to elevate basal cAMP levels when incubated with unstimulated cells. Stimulation of IBMX-treated (0.1 but not 1.0 or 4.0 mM) cells with bradykinin, however, did result in increased cAMP levels, presumably due to PGI2 formation and subsequent activation of adenylate cyclase. In addition to phosphodiesterase inhibition, IBMX inhibited PGI2 formation (72% at 1 mM) in a dose-dependent manner so that, at higher doses of IBMX, cAMP levels returned to baseline. Thus, prostacyclin synthesis inhibition by IBMX could not be attributed to elevated cAMP. In other experiments, IBMX (1 mM) was found to directly inhibit arachidonic acid release (32%) and arachidonic acid metabolism (65%) in endothelial cells and to inhibit arachidonic acid conversion to PGE2 by sheep seminal vesicle microsomes (65%). These data suggest that IBMX directly inhibits both phospholipase and cyclooxygenase activities. These experiments do not support the contention that cAMP regulates these enzymes in cultured aortic endothelial cells.
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PMID:Arachidonic acid metabolism in cultured aortic endothelial cells. Effect of cAMP and 3-isobutyl-1-methylxanthine. 257 80

Isolated rabbit renal papillary collecting tubule cells were used to examine the effects of phosphodiesterase inhibitors on intracellular cyclic AMP and prostaglandin synthesis. Experiments performed on confluent primary tissue cultures demonstrated that bradykinin increases intracellular cyclic AMP by a prostaglandin-dependent mechanism. Phosphodiesterase inhibitors induced a dose-dependent decrease in bradykinin-stimulated prostaglandin synthesis. Fifty percent inhibition occurred with approximately 0.7 mM 3-isobutyl-1-methylxanthine (IBMX). Inhibition was found to be reversible. IBMX did not inhibit bradykinin-induced prostaglandin synthesis as a result of increased intracellular cyclic AMP. The nonmethylxanthine phosphodiesterase inhibitor RO 20-1724 also reduced bradykinin-stimulated prostaglandin synthesis. IBMX inhibited calcium-ionophore-A23187-induced prostaglandin synthesis but did not inhibit arachidonic acid stimulation of prostaglandin synthesis. The data demonstrate that bradykinin increased renal papillary collecting tubule cell cyclic AMP in a prostaglandin-dependent manner. Based on the data presented, phosphodiesterase inhibitors act to decrease arachidonic acid availability for prostaglandin synthesis, independent of changes in cellular cyclic AMP content.
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PMID:Effect of phosphodiesterase inhibitors on bradykinin-mediated prostaglandin E2 and cyclic AMP synthesis in renal papillary collecting tubule cells. 258 85


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