Glycerophosphrylocholine (GPC) is a renal medullary compatible organic osmolyte that is derived from choline via phosphatidylcholine, which is catalyzed in part by phospholipase A2 (PLA2) and its degradation by GPC: choline phosphodiesterase (GPC: choline PDE). We found that caffeine elevated intracellular free calcium ([Ca2+]i) and GPC level in cultured MDCK cells, canine kidney epithelial cells, and propose a possible biochemical mechanism. When MDCK cells were incubated for 3 h with 1 to 10 mM caffeine, cellular GPC was elevated in a dose-dependent manner, and this occurred independently of the extracellular osmolality. Caffeine stimulated the rate of [14C]choline incorporation into [14C]GPC and PLA2 activity. Whereas, GPC: choline PDE activity was accompanied by less of increase. These enzyme changes demonstrate the increased net synthesis of MDCK GPC. In order to identify what triggers the PLA2 activation, [Ca2+]i was measured by using a fluorescence dye, Fura-2. Caffeine (10 mM) resulted in a typical transient increase in MDCK [Ca2+]i concentration, and this increase was greatly inhibited by pretreatment of MDCK cells with 10 mM ryanodine for 5 min. Ryanodine (10 mM) also inhibited the caffeine-induced stimulation of PLA2 activity. These findings provide the first evidence that caffeine in MDCK cells causes a ryanodine-inhibitable increase of [Ca2+]i and PLA2 activity, resulting in cellular GPC accumulation.
Animal ; Caffeine/pharmacology* ; Calcium/metabolism* ; Carbon Radioisotopes ; Cell Line ; Choline/metabolism ; Dogs ; Glycerylphosphorylcholine/metabolism* ; Kidney/cytology ; Phospholipases A/metabolism* ; Phospholipases A/drug effects ; Phospholipases A/antagonists & inhibitors ; Phosphoric Diester Hydrolases/metabolism ; Phosphoric Diester Hydrolases/drug effects ; Ryanodine/pharmacology* ; Ryanodine/metabolism

Animals ; Anti-Asthmatic Agents ; therapeutic use ; Asthma ; drug therapy ; etiology ; Humans ; Phosphodiesterase Inhibitors ; pharmacology ; Phospholipase D ; physiology ; Phosphoric Diester Hydrolases ; physiology

Since the introduction of the phosphodiesterase type 5 (PDE-5) inhibitor sildenafil in 1998, there has been a fundamental change in the treatment of erectile dysfunction (ED). Sildenafil has already been used by over 20 million men in over 100 countries, with a death rate similar to that of general population. The success rate of sildenafil amounts to an average of over 80%, and sildenafil has become the first choice for patients with ED. The development of two new PDE-5 inhibitors, vardenafil and tadalafil, has added to the options for the treatment of ED. In this review, a comparison is made of the pharmcodynamics, pharmacokinetics and adverse reactions between the three PDE-5 inhibitors to assess their efficacy and safety.
3',5'-Cyclic-GMP Phosphodiesterases ; Cyclic Nucleotide Phosphodiesterases, Type 5 ; Erectile Dysfunction ; drug therapy ; Humans ; Male ; Phosphodiesterase Inhibitors ; adverse effects ; pharmacokinetics ; therapeutic use ; Phosphoric Diester Hydrolases ; physiology ; Piperazines ; therapeutic use ; Purines ; Sildenafil Citrate ; Sulfones

Autotaxin (ATX), a member of nucleotide pyrophosphatase/phosphodiesterase (NPP) family, is also named as phosphodiesterase Iα (PD-Iα) or NPP2. ATX is the unique member among the NPPs that can function as a lysophospholipase D (lysoPLD), converting lysophosphatidylcholine into lysophosphatidic acid (LPA). LPA acts on specific G-protein-coupled receptors to elicit a wide range of cellular response, including cell proliferation, cell migration and cell contraction, etc. As the major LPA-producing phospholipase, many ATX's features and functions are dependent on the production of LPA. ATX and LPA together form the ATX-LPA functional axis. The present review summarizes the current progress in function and biological activities of ATX-LPA axis.
Animals ; Cell Movement ; physiology ; Cell Proliferation ; Humans ; Lysophosphatidylcholines ; metabolism ; Lysophospholipids ; metabolism ; physiology ; Phospholipases ; metabolism ; Phosphoric Diester Hydrolases ; metabolism ; physiology ; Receptors, G-Protein-Coupled ; physiology

Erectile response is centrally and peripherally regulated by androgens. The original insights into the mechanisms of action of androgens were that androgens particularly exert effects on libido and that erections in response to erotic stimuli were relatively androgen-independent. It was shown that sexual functions in men required androgen levels at the low end of reference values of testosterone. So it seemed that testosterone was not useful treatment for men with erectile difficulties, particularly following the advent of the phosphodiesterase type 5 (PDE5) inhibitors. However, approximately 50% of those treated with PDE5 inhibitors discontinue their treatment. A number of recent developments shed new light on testosterone treatment of erectile dysfunction (ED) in aging men. (1) A recent insight is that, in contrast to younger men, elderly men might require higher levels of testosterone for normal sexual functioning. (2) Several studies have indicated that PDE5 inhibitors are not always sufficient to restore erectile potency in men, and that testosterone improves the therapeutical response to PDE5 inhibitors considerably. (3) There is growing insight that testosterone has profound effects on tissues of the penis involved in the mechanism of erection and that testosterone deficiency impairs the anatomical and physiological substrate of erectile capacity, reversible upon androgen replacement. The synthesis of PDE5 is upregulated by androgens, and the arterial inflow into the penis is improved by giving androgen. The above invites a re-examination of the merits of giving testosterone to aging men with ED. The beneficial effects of PDE5 inhibitors may only be optimally expressed in a eugonadal environment.
3',5'-Cyclic-GMP Phosphodiesterases ; Aging ; physiology ; Animals ; Cyclic Nucleotide Phosphodiesterases, Type 5 ; Humans ; Male ; Middle Aged ; Penile Erection ; drug effects ; physiology ; Penis ; anatomy & histology ; drug effects ; Phosphodiesterase Inhibitors ; pharmacology ; therapeutic use ; Phosphoric Diester Hydrolases ; physiology ; Piperazines ; therapeutic use ; Purines ; Sildenafil Citrate ; Sulfones ; Testosterone ; blood ; physiology

This study was conducted to investigate the effects of extremely low frequency electromagnetic fields (EMF) on signal pathway in plasma membrane of cultured cells (RAW 264.7 cells and RBL 2H3 cells), by measuring the activity of phospholipase A2 (PLA2), phospholipase C (PLC) and phospholipase D (PLD). The cells were exposed to the EMF (60 Hz, 0.1 or 1 mT) for 4 or 16 h. The basal and 0.5 microM melittin-induced arachidonic acid release was not affected by EMF in both cells. In cell-free PLA2 assay, we failed to observe the change of cPLA2 and sPLA2 activity. Also both PLC and PLD activities did not show any change in the two cell lines exposed to EMF. This study suggests that the exposure condition of EMF (60 Hz, 0.1 or 1 mT) which is 2.4 fold higher than the limit of occupational exposure does not induce phospholipases-associated signal pathway in RAW 264.7 cells and RBL 2H3 cells.
Arachidonic Acid ; Cell Line ; Cell Membrane ; Cells, Cultured ; Electromagnetic Fields ; Magnets ; Occupational Exposure ; Phospholipase D ; Phospholipases ; Phospholipases A2 ; Pyridoxal ; Signal Transduction ; Type C Phospholipases

OBJECTIVESTo investigate the effects of antisense oligodeoxynucleotide(ASON) on the cyclic nucleotide monophosphates (cNMP) in smooth muscle cells of human corpus cavernosum, and provide experimental groundwork for the gene therapy of erectile dysfunction.

METHODSPDE5 gene ASON(containing exon 1) was transfected into the corpus cavernosum smooth muscle cells with the presence of liposome DOTAP. Another sense oligodeoxynucleotide(SON) and 1% of bovine serum were also transducted into the cells as controls. Two of cNMP, cAMP and cGMP, were probed and measured by ELISA at 1, 2, 4, 6, 10, 24 and 48 h after transfection.

RESULTSAfter transfection, the level of cGMP(1-6 h) in human corpus cavernosum smooth muscle cells was significantly higher than that in controls(P < 0.01).

CONCLUSIONSThe PDE5 gene ASON had been showed to manifest stimulative effect on the cGMP in smooth muscle cells of human corpus cavernosum in vitro, and it provides experimental groundwork for the gene therapy of erectile dysfunction.

3',5'-Cyclic-GMP Phosphodiesterases ; antagonists & inhibitors ; genetics ; Cyclic AMP ; metabolism ; Cyclic GMP ; metabolism ; Cyclic Nucleotide Phosphodiesterases, Type 5 ; Humans ; Male ; Muscle, Smooth ; drug effects ; metabolism ; Oligodeoxyribonucleotides, Antisense ; pharmacology ; Penis ; cytology

We previously reported that some components of ginsenosides decreased mediator releases evoked by the activation of mast cells with specific antigen-antibody reactions. This study aimed to assess the effects of ginsenosides (Rb2, Re) on the mechanism of histamine release in the mast cell activation. We partially purified guinea pig lung mast cells by using enzyme digestion, the rough and the discontinuous percoll density gradient method. Mast cells were sensitized with IgG1 and challenged with ovalbumin (OA). Histamine was assayed by fluorometric analyzer, leukotrienes by radioimmunoassay. Phospholipase D (PLD) activity was assessed more directly by the production of (3H)phosphatidylbutanol (PBut) which was produced by PLD-mediated transphosphatidylation in the presence of butanol. The amount of 1,2-diacylglycerol (DAG) were measured by the (3H)DAG labeled with (3H)palmitic acid or (3H)myristic acid. Pretreatment of Rb2 (300 microgram) significantly decreased histamine release by 60%, but Re (300 gg) increased histamine release by 34%. Leukotrienes release in Rb2 was decreased by 40%, Re was not affected in the leukotrienes release during mast cell activations. An increasing PLD activity during mast cell activation was decreased by the dose-dependent manner in the pretreatment of Rb2, but Re pretreatment facilitated the increased PLD activity during mast cell activation. The amount of DAG produced by phospholipase C (PLC) activity was decreased by Rb2 pretreatment, but Re pretreatment was not affected. The amount of mass DAG was decreased by Rb2 and Re pretreatment during mast cell activation. The data suggest that Rb2 purified from Korean Red Ginseng Radix inhibits the DAG which is produced by the activation of mast cells with antigen-antibody reactions via both phosphatidylinositide-PLC and phosphatidylcholine-PLD systems, and then followed by the inhibition of histamine release. However, Re increases histamine release by stimulation of DAG production, which is mediated by phosphatidylcholine-PLD system rather than by phosphatidylinositide-PLC system, but inhibits the mass DAG production. Thus, it could be inferred that other mechanisms play a role in the increase of histamine release during mast cell activation.
Animals ; Antigen-Antibody Reactions* ; Digestion ; Ginsenosides* ; Guinea Pigs* ; Guinea* ; Histamine Release* ; Histamine* ; Immunoglobulin G ; Leukotrienes ; Lung* ; Mast Cells* ; Ovalbumin ; Panax ; Phospholipase D ; Radioimmunoassay ; Type C Phospholipases

BACKGROUND AND OBJECTIVES: Time-phasic development of nitrate tolerance in cardiovascular diseases is very important because it can contribute to the advent of blunted vasodilation or rebound ischemia even during continuous NTG treatment. In such a condition, we should change the therapeutic regimen of nitrate treatment to prevent the worsening of symptoms. MATERIALS AND METHODS: We created a nitrate-tolerant rat model using an osmotic minipump, and we examined the hemodynamic response to bolus NTG infusion in vivo. We checked the phosphodiesterase (PDE) 1A1 mRNA and protein level by relative quantitative RT-PCR and western blot analysis. We used 8-cpt-cGMP for investigating the development of a time-phasic nitrate tolerance mechanism after nitrate infusion. RESULTS: NTG-treated rats revealed a significant decrease in NTG-induced MAP drop (nitrate tolerance) from 1-day and this continued to the third day. The mRNA and protein levels of PDE1A1 similarly increased during these periods. CONCLUSION: This study revealed the development of time-phasic nitrate tolerance from the the aspects of in vivo hemodynamic responses and PDE 1A1 gene expression, and our work supports the need for further investigation to come up with a different therapeutic strategy and new drugs.
Animals ; Aorta ; Blotting, Western ; Cardiovascular Diseases ; Gene Expression ; Hemodynamics* ; Ischemia ; Models, Animal ; Nitrates ; Phosphoric Diester Hydrolases ; Rats ; RNA, Messenger ; Vasodilation

OBJECTIVETo investigate the changes in the expression of phospholipase C-gamma1tyr783 (PLC-γ1tyr783) in the condylar cartilage of a young rat during functional mandibular protraction. This work also explores the function of PLC-γ1tyr783 in the rat mandibular condylar cartilage bone remodeling, which could provide experimental evidence for clinical bone ortho- pedic work.

METHODSA total of 60 four-week-old male Sprague-Dawley (SD) rats were used in this study. The rats were divided equally and randomly into experimental group and control group. The functional appliances that were fitted to the upper incisors of the animals in the experimental group were worn 24 h a day after the rats were fed for 7 d with homemade pellet feed. The animals in the experimental group, along with their matched controls, were sacrificed after 1, 3, 7, 14, 21, and 28 d. The bilateral condylar was fixed, decalcified, dehyded, and then conventional paraffin embedded. Immunohisto- chemistry of PLC-γ1tyr783 was applied to observe its express distribution and variation.

RESULTSThe expression of PLC-γ1tyr783 decreased gradually in the control group, which showed age-related changes (P > 0.05). On the 14th day, PLC-γ1tyr783 expres- sion in the experimental group was significantly higher than that in the control group. PLC-γ1tyr783 expression began to appear statistically and significantly different between the two groups (P < 0.01).

CONCLUSIONPLC-γ1tyr783 is involved in the bone remodeling process of the rat condylar cartilage after functional mandibular-protraction.

Animals ; Bone Remodeling ; Cartilage ; Male ; Mandibular Condyle ; Phospholipase C gamma ; Phosphoric Diester Hydrolases ; Rats ; Rats, Sprague-Dawley