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

Androgen has been claimed for so long as a pivotal hormone in regulating male sexual function, acting both at the central and peripheral level. We believe that androgen is indeed the main synchronizer of sexual activity regulating libido and enzymes as nitric oxide synthase (NOS) and phosphodiesterase type 5 ( PDE5) , which are crucial for the erectile process. The main action of androgen is to timely adjust the erectile process as a function manifestation of sexual desire, therefore finalizing erection to sex.
Androgens ; pharmacology ; physiology ; Animals ; Male ; Nitric Oxide Synthase ; metabolism ; Penile Erection ; drug effects ; physiology ; Phosphoric Diester Hydrolases ; metabolism ; Rats

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

OBJECTIVETo explore the molecular mechanism of APL cell resistance to ATRA.

METHODSThe ATRA sensitive and resistant APL cell lines, NB4 and NB4-R1, were used as in vitro models. The effects of specific inhibitors and activators of adenylate cyclase (AC) and phosphodiesterase (PDE) on ATRA-induced differentiation was evaluated by cell morphology, cell surface antigen expression and nitroblue-tetrazolium (NBT) reduction assays.

RESULTSSQ22536, a specific antagonist of AC, could dramatically block ATRA-induced NB4 cell differentiation. When ATRA + SQ22536 group compared with ATRA group, the positivity of CD11b decreased from (95.9 +/- 2.5)% to (60.3 +/- 7.1)%, while the A(540) in NBT reduction assay decreased from 0.585 +/- 0.092 to 0.170 +/- 0.028 (P < 0.05). Forskolin, an agonist of AC, could overcome the resistance of NB4-R1 cells to ATRA. When ATRA + forskolin group compared with ATRA group, the positivity of CD11b increased from (34.3 +/- 5.3)% to (94.6 +/- 2.4)%, while the A(540) in NBT reduction assay increased from 0.110 +/- 0.028 to 0.395 +/- 0.049 (P < 0.05). In contrast, the specific antagonist and agonist of PDE, 3-isobutyl-1-methylxanthine (IBMX) and calmodulin, exerted little impact on ATRA treatment.

CONCLUSIONSThe defaults in the initiation of AC activation may contribute to the resistance to ATRA in some APL cells.

Adenine ; analogs & derivatives ; pharmacology ; Adenylyl Cyclase Inhibitors ; Adenylyl Cyclases ; metabolism ; Antineoplastic Agents ; pharmacology ; CD11b Antigen ; metabolism ; Cell Differentiation ; drug effects ; Cell Line, Tumor ; Drug Resistance, Neoplasm ; drug effects ; Enzyme Activation ; drug effects ; Enzyme Inhibitors ; pharmacology ; Humans ; Leukemia, Promyelocytic, Acute ; metabolism ; pathology ; Phosphoric Diester Hydrolases ; metabolism ; Tretinoin ; pharmacology

OBJECTIVETo evaluate the effect of Xuefu Zhuyu Capsule ()-containing serum (XFZY-CS) on EphB4/ephrinB2 and its reverse signal in human microvascular endothelial cell-1 (HMEC-1).

METHODSXFZY-CS and the blank control serum were collected. HMEC-1 cells were randomly assigned to 6 groups including the concentration 1.25%, 2.5%, and 5% XFZY-CS groups and their blank serum control ones. The angiogenesis effect of XFZY-CS was tested with an in vitro tube formation assay and the best condition of pro-angiogenesis was determined. The effect of XFZY-CS on EphB4/ephrinB2 and the reverse signal were determined by Western blot and real-time quantitative polymerase chain reaction, respectively; we also confifirmed the results through activating and inhibiting the reverse signal by EphB4/fc and pyrophosphatase/ phosphodiesterase2 (PP2).

RESULTSXFZY-CS promoted angiogenesis at the concentration of 2.5% corresponding serum after being cultured for 48 h, while inhibited angiogenesis at the concentration of 5% after culturing for 48 and 72 h. Under the 2.5% serum concentration, XFZY up-regulated the expression of EphB4-mRNA at 12 h (P<0.05), and down-regulates its expression at 24 h (P<0.01). Protein expression of EphB4 was apparently up-regulated at 12 h and down-regulated at 24 h. The phosphorylation of ephrinB2 increased at 9 h (P<0.05). In addition, 2.5% XFZY-CS played a similar role as the reverse signaling activator EphB4/Fc ranging from 0.5 to 5 μg/mL (P>0.05). XFZY-CS also reduced the inhibitive effect of PP2 in limited periods.

CONCLUSIONSEphB4/ephrinB2 was the upstream signal in the process of angiogenesis and its reverse signaling was responsible for XFZY's effect on promoting angiogenesis.

Adult ; Capsules ; Drugs, Chinese Herbal ; pharmacology ; Endothelial Cells ; drug effects ; metabolism ; Ephrin-B2 ; metabolism ; Gene Expression Regulation ; drug effects ; Humans ; Male ; Microvessels ; pathology ; Middle Aged ; Neovascularization, Physiologic ; drug effects ; genetics ; Phosphoric Diester Hydrolases ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Receptor, EphB4 ; genetics ; metabolism ; Serum ; metabolism ; Time Factors ; Young Adult

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

OBJECTIVETo investigate the molecular mechanism of human ether-a-go-go-related gene (HERG) potassium channels regulated by protein kinase A (PKA) in a human cell line.

METHODSHERG channels were stably expressed in human embryonic kidney (HEK) 293 cells, and currents were measured with the patch clamp technique. The direct phosphorylation of HERG channel proteins expressed heterologously in Xenopus laevis oocytes was examined by (32)P labeling and immunoprecipitation with an anti-HERG antibody.

RESULTSElevation of the intracellular cAMP-concentration by incubation with the adenylate cyclase activator, forskolin (10 micromol/L), and the broad range phosphodiesterase inhibitor, IBMX (100 micromol/L), caused a HERG tail current reduction of 83.2%. In addition, direct application of the membrane permeable cAMP analog, 8-Br-cAMP (500 micromol/L), reduced the tail current amplitude by 29.3%. Intracellular application of the catalytic subunit of protein kinase A (200 U/ml) led to a tail current decrease by 56.9% and shifted the activation curve by 15.4 mV towards more positive potentials. HERG WT proteins showed two phosphorylated bands, an upper band with a molecular mass of approximately 155 kDa and a lower band with a molecular mass of approximately 135 kDa, indicating that both the core- and the fully glycosylated forms of the protein were phosphorylated.

CONCLUSIONSPKA-mediated phosphorylation of HERG channels causes current reduction in a human cell line. The coupling between the repolarizing cardiac HERG potassium current and the protein kinase A system could contribute to arrhythmogenesis under pathophysiological conditions.

1-Methyl-3-isobutylxanthine ; pharmacology ; 8-Bromo Cyclic Adenosine Monophosphate ; pharmacology ; Adenylyl Cyclases ; metabolism ; Animals ; Anti-Arrhythmia Agents ; pharmacology ; Cation Transport Proteins ; Cell Line ; Colforsin ; pharmacology ; Cyclic AMP ; metabolism ; Cyclic AMP-Dependent Protein Kinases ; metabolism ; DNA-Binding Proteins ; ERG1 Potassium Channel ; Enzyme Activation ; drug effects ; Ether-A-Go-Go Potassium Channels ; Female ; Humans ; Membrane Potentials ; drug effects ; Microinjections ; Oocytes ; Patch-Clamp Techniques ; Phenethylamines ; pharmacology ; Phosphodiesterase Inhibitors ; pharmacology ; Phosphoric Diester Hydrolases ; drug effects ; metabolism ; Phosphorylation ; Potassium Channels ; genetics ; metabolism ; physiology ; Potassium Channels, Voltage-Gated ; RNA, Complementary ; administration & dosage ; genetics ; Sulfonamides ; pharmacology ; Trans-Activators ; Transcriptional Regulator ERG ; Xenopus laevis