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)

This study was conducted to further characterize the previously described phenomenon of growth inhibition of neoplastically transformed C3H/10T1/2 cells (T10T1/2) by nontransformed C3H/10T1/2 clone 8 mouse embryo fibroblast (10T1/2) cells in the presence of inhibitors of cyclic adenosine 3':5'-monophosphate (cAMP) phosphodiesterase. The cAMP phosphodiesterase inhibitor dl-4-(3-butoxy-4-methoxybenzyl)-2-imidazolidinone (RO20-1724) was shown to be completely nontoxic to T10T1/2 cells at 10(-4) M, yet when added to mixed cultures of T10T1/2 cells and postconfluence growth-arrested 10T1/2 cells, colony formation and [3H]thymidine incorporation into T10T1/2 cells were virtually eliminated. This effect was dose dependent and was reversible upon drug withdrawal. In 10T1/2 cells, RO20-1724 caused a dose-dependent increase in cAMP levels from about 5 to 150 pmol/10(6) cells; in T10T1/2 cells, 10(-4) M drug treatment caused a 5-fold elevation in cAMP without a clear dose dependency. Cyclic guanosine 3':5'-monophosphate levels in 10T1/2 cells fell by 50% with drug treatment but were unmeasurable in T10T1/2 cells. When intracellular cyclic AMP levels were elevated by the adenyl cyclase stimulator forskolin, growth inhibition of T10T1/2 cells was again induced in mixed cultures but was not observed when added to T10T1/2 cells alone. Addition of RO20-1724 to low concentrations of forskolin produced a greater than additive effect on growth inhibition. Growth inhibition of T10T1/2 cells by RO20-1724 was shown to (a) require contact with, or extremely close proximity to, a confluent monolayer of 10T1/2 cells, (b) be maximum when seeded upon a growth-inhibited monolayer and not an actively growing 10T1/2 culture, and (c) not be decreased by continuous agitation of the culture medium, indicating that readily diffusible inhibitory factors are not involved. A model is presented whereby transformed cells can respond to but cannot themselves generate growth-inhibitory signals produced by post-confluence growth-inhibited nontransformed cells. The existence of these cellular interactions may well explain problems in the quantitation of transformed foci encountered in the use of this cell line as an assay system for chemical and physical carcinogens.
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PMID:Requirements for and kinetics of growth arrest of neoplastic cells by confluent 10T1/2 fibroblasts induced by a specific inhibitor of cyclic adenosine 3':5'-phosphodiesterase. 298 40

Theophylline and its derivatives have been used in the treatment of asthma for over 50 years, but since the advent of more potent bronchodilators their use has become cloaked in controversy. Their continued existence results from their undoubted usefulness in severe acute asthma, nocturnal asthma, childhood asthma and moderate to severe chronic airflow limitation, and because of habitual use by physicians in other situations. The precise mechanism of action of theophylline remains uncertain. The role of phosphodiesterase inhibition and adenosine antagonism has been reviewed and the clinical significance of the anti-inflammatory action of theophylline discussed. Theophylline has unpredictable metabolism when first administered, and continued monitoring of drug concentrations is essential. Commonly encountered adverse effects may occur at therapeutic serum concentrations, frequently necessitating drug withdrawal. The overlapping therapeutic and toxic theophylline serum ranges can lead to life-threatening adverse effects at the upper end of the therapeutic range, especially in the elderly in whom special precaution is required.
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PMID:Theophylline. Current thoughts on the risks and benefits of its use in asthma. 847 Nov 84

Previous studies have demonstrated a role for adenosine in mediating opiate effects. This study examines the effects of indirect activation of adenosine receptors, via treatment with adenosine kinase inhibitors, on the expression of opiate withdrawal in mice. Mice receive chronic morphine treatment via implantation of subcutaneous morphine pellets (75 mg) for 72 h. Mice then receive parenteral treatment with adenosine kinase inhibitors, either 5'-amino-5'-deoxyadenosine (2, 5, 20, 40 mg/kg, intraperitoneal or i.p.) or iodotubericidin (1, 2, 5 mg/kg, i.p.), followed by naloxone injection and opiate withdrawal signs are measured over 20 min. Both adenosine kinase inhibitors significantly reduce the following opiate withdrawal signs in a dose-dependent manner compared to vehicle: withdrawal jumps, teeth chattering, forepaw tremors, and forepaw treads. Additionally, 5'-amino-5'-deoxyadenosine significantly reduces withdrawal-induced diarrhea and weight loss. Effects of 5'-amino-5'-deoxyadenosine (40 mg/kg) on opiate withdrawal signs appear to be mediated via adenosine receptor activation as they are reversed by pretreatment by adenosine receptor antagonist caffeine (20 mg, i.p.) but not by selective phosphodiesterase inhibitor Ro 20-1724 (10 mg/kg, i.p.). Adenosine receptor activation via adenosine kinase inhibitor treatment attenuates opiate withdrawal and these agents may be generally useful in the treatment of drug withdrawal syndromes.
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PMID:Adenosine kinase inhibitors attenuate opiate withdrawal via adenosine receptor activation. 986 23

Erectile dysfunction (ED) and endothelial dysfunction are common in individuals with multiple cardiovascular risk factors (CRFs) and are longitudinal predictors of cardiovascular events. ED is associated with systemic endothelial cell activation/dysfunction independent from CRFs or from diffuse, unrecognized vascular damage. The pathogenesis of endothelial dysfunction and ED is intimately linked through decreased expression and activation of endothelial nitric oxide (NO) synthase and the subsequent physiologic actions of NO. Furthermore, reduced biologic activity of endothelium-derived NO links atherosclerosis to ED and underscores the role of altered endothelium in the pathogenesis of both conditions. Evidence-based data suggest that daily use of phosphodiesterase type-5 inhibitors (PDE5-i) improves endothelial and erectile functions and that this benefit is lost upon drug withdrawal. Daily PDE5-i may also improve lower tract urinary symptoms related to benign prostatic hyperplasia through a reduction of adrenergic overtone. The relevance for these drugs in the prevention of complications in internal medicine diseases, i.e. cardiovascular disease, clotting disorders and autoimmune disease is uncertain. Finally, endothelial dysfunction is present in testosterone deficiency syndromes and replacement therapy is able to revert ED and to improve endothelial function. Aim of the present review is to discuss the systemic effects of drugs designed to treat ED, such as testosterone and PDE5-i, with regard to safety, unwanted effects and efficacy in improving endothelial function; finally, a goal-oriented approach to rehabilitation using daily vs. on-demand PDE5-i in difficult patients is discussed.
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PMID:Endothelial effects of drugs designed to treat erectile dysfunction. 1912 29

Erectile dysfunction (ED) is a common disorder that affects the quality of life of both men and their partners. The phosphodiesterase type 5 inhibitor is the first-line drug for ED. Recent researches found that long-term administration of low-dose phosphodiesterase type 5 inhibitors to be a safe and effective therapy for ED, as well as for couples who may prefer more convenience and spontaneity in their sexual activities. Besides, it provides a new therapeutic option for refractory ED. Its action mechanism mainly involves the improvement of the endothelial function of penile vessels and/or maintenance of the function and number of smooth muscle cells. However, whether this therapy can maintain the improved erection function after drug withdrawal needs further studies.
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PMID:[Long-term administration of low-dose phosphodiesterase type 5 inhibitors for erectile dysfunction: an update]. 2370 Jul 21