BACKGROUND: Intercellular adhesion molecule(ICAM)-1 mediates cell to cell adhesion by acting as a receptor for leukocyte surface antigen. Increased ICAM-1 expression was observed in chronic inflammatory skin diseases, such as psoriasis, atopic dermatitis and allergic contact dermatitis. Adenosine is an endogenous antiinflammatory agent released by cells under metabolically unfavorable conditions, recently the studies about antiinflammatory effects of adenosine in various tissues were increased, but there are few studies about the effect of adenosine on epidermal keratinocytes. OBJECTIVE: We investigated the effects of adenosine on ICAM-1 expression in cultured human keratinocyte cell line HaCaT cells. METHODS: Our study analyses the ICAM-1 expression in HaCaT cells by various stimulants and the effects of adenosine, adenosine receptor agonist&antagonist and an inhibitor of cellular adenosine uptake on ICAM-1 expression of cells stimulated by IFN-gamma through the cell-ELISA (enzyme-linked immunosorbent assay)&FACS (fluorescence-activated cell sorter) analysis. RESULTS: The results are summerized as follows: 1. ICAM-1 expression was significantly increased by IFN-gamma(500U/ml), IFN-gamma&TNF-alpha(10-8M) and IFN-gamma&LPS(10-8M)(p<0.05), but not by TNF-alpha, LPS and TNF-alpha & LPS. 2. Incubation of HaCaT cells with IFN-gamma(1-2000U/ml) for 48 hours induced dose-dependent expression of ICAM-1 at above 500U/ml of IFN-gamma. 3. Adenosine had no effect on ICAM-1 expression of unstimulated cells. 4. Adenosine(esp. 10-4M) significantly inhibited ICAM-1 expression of cells stimulated by IFN-gamma(p<0.01). 5. Adenosine(10-4M) significantly inhibited ICAM-1 expression of cells stimulated by IFN-gamma(p<0.01), IFN-gamma & TNF-alpha(p<0.05) and IFN-gamma&LPS. 6. The inhibition of ICAM-1 expression was not observed when cells were preincubated with an adenosine A1 receptor agonist(R-PIA) or an adenosine A2 receptor agonist (NECA). 7. The inhibition of ICAM-1 expression of adenosine was not affected by pretreatment state with an adenosine A1 & A2 receptor antagonist(theophylline)(p<0.01). 8. The inhibition of ICAM-1 expression of adenosine was not observed by pretreatment state with an inhibitor of adenosine cellular uptake (dipyridamole). CONCLUSION: High concentration of adenosine inhibits enhanced ICAM-1 expression on HaCaT cells by stimulated with IFN-gamma and these inhibitory effects of adenosine are mediated through other adenosine receptors excect adenosine A1 and A2 receptors. And we suggest that there may be an unknown intracellular mechanism about inhibition of ICAM-1 expression via intracellular-uptaken adenosine.
Adenosine* ; Antigens, Surface ; Cell Adhesion ; Cell Line* ; Dermatitis, Allergic Contact ; Dermatitis, Atopic ; Humans* ; Intercellular Adhesion Molecule-1* ; Keratinocytes* ; Leukocytes ; Psoriasis ; Receptor, Adenosine A1 ; Receptors, Adenosine A2 ; Receptors, Purinergic P1 ; Skin Diseases ; Tumor Necrosis Factor-alpha

Adenosine Triphosphate ; Mouth ; metabolism ; Receptors, Purinergic P2X ; metabolism

BACKGROUND: Extracellular ATP, released from platelets and nerve endings, plays significant roles in the regulation of circulation. The effects of ATP depend on the location of the vessels and the species of experimental animals. Until now, studies were limited to arteries, so we compared the effects of ATP in rat vena cava with those in the aorta and attempted to identify the characteristics of their receptors. METHODS: Vascular rings were isolated from the rat inferior vena cava and descending thoracic aorta. Endothelial cells were preserved or removed by gentle rubbing. The isometric contractions were recorded on polygraph using a force transducer. RESULTS: In the vena cava ring precontracted by 100 nM norepinephrine (NE), ATP elicited relaxations in a dose-dependent manner. These effects were abolished by removal of the endothelium or pretreatment with a nitric oxide synthase inhibitor. Relaxations to ATP in the vena cava (EC50 :9.9 microM) were less potent than those in the aorta (1.7 microM). The relative order of potencies was ADP>ATP>AMP>adenosine, but the maximal relaxation to ADP was smaller than to ATP. ATP-induced vasorelaxation was blocked by suramin, a nonselective antagonist for P2 purinoceptor and reactive blue-2, a P2Y blocker. At basal tension, ATP contracted the vena cava dose-dependently and these effects were potentiated by endothelium-removal. Contractions in the vena cava were also less potent than in the aorta, and the order of potencies was alpha, beta-MeATP>UTP>ATP>ADP>AMP=adenosine. ATP-induced vasoconstriction was blocked by suramin and alpha, beta-MeATP, a desensitizing antagonist of P2X purinoceptor, and potentiated by pretreatment with UTP. CONCLUSION: These results suggest that ADP and ATP acts on P2Y1- and P2Y2-purinoceptor in the endothelium, respectively and induces vasorelaxation of the vena cava, which is mediated by nitric oxide. Since ATP and UTP induced vasoconstriction in endothelium-denuded condition, it may be mediated by the activation of the P2X and P2Y4, 6 purinoceptor on smooth muscles, respectively.
Adenosine Diphosphate ; Adenosine Triphosphate ; Animals ; Aorta ; Aorta, Thoracic ; Arteries ; Endothelial Cells ; Endothelium ; Isometric Contraction ; Muscle, Smooth ; Nerve Endings ; Nitric Oxide ; Nitric Oxide Synthase ; Norepinephrine ; Rats* ; Receptors, Purinergic P2 ; Receptors, Purinergic P2X ; Receptors, Purinergic* ; Relaxation ; Suramin ; Transducers ; Uridine Triphosphate ; Vasoconstriction ; Vasodilation ; Vena Cava, Inferior*

BACKGROUND: In two-kidney one clip Goldbaltt hypertensive rats(2K1C GHR), clipped kidney may be exposed to low pressure and unclipped kidney to high pressure. In addition, both kidneys may have a different amount of adenosine which is increased by ischemia and plays an important role for renin release. The aim of this study was to invstigate the responsmiveness for renin release to adenosine agonists and antagonist in clipped and unclipped kidney of 2K1C GHR. METHODS: Emplying kidney slices from both unclipped and unclipped kidney of 2K1C GHR, the alteration by adenosine agonists and antagonist of renin release was studied. RESULTS: The renal renin content and basal renin release from unclipped kidney slices were suppressed, whereas those from clipped kidney were augmented Adenosine Al receptor agonist, cyclohexyladenosne(CHA), phenylisopropyl adenosine(PIA) and adenosine caused a decrease in renin release from clipped kidney slices. Adenosine A2 receptor agonist, NECA, and nonspecific adenosine receptor aganist, 2-chloroadenosine(CA) caused an increase in renin release from clipped kidney slices. Adenosine receptor antagonist, 8-phenyltheophylline(8-PT) caused an increase in renin release from clipped kidney slices. In unclipped kidney, however, the renin release in response to NECA, CA or 8-PT was reversed and the decreasing effect of renin release to CHA and adenosine was slightly inereased. CONCLUSION: These results suggest that the responsiveness of adenosine receptors, which may participate in renin release is modified in clipped and unclipped kidney of 2K1C GHR.
Adenosine* ; Adenosine-5'-(N-ethylcarboxamide) ; Animals ; Hypertension, Renovascular ; Ischemia ; Kidney ; Rats* ; Receptors, Adenosine A2 ; Receptors, Purinergic P1 ; Renin*

Animals ; Oocytes ; metabolism ; physiology ; Receptors, G-Protein-Coupled ; physiology ; Receptors, Purinergic P2X ; physiology ; Xenopus laevis

P2X7 receptor is a member of ATP-gated non-selective cation channels. P2X7 receptor is widely distributed in vivo, and its expression is always observed to be up-regulated in the pathological inflammatory circumstances. P2X7 receptor has an unusual property of forming membrane pore during prolonged agonist exposure or high concentrations of agonist activation, different from other members of P2X receptors (P2X1-6). Because of this property, P2X7 receptor has been implicated in inflammatory cytokine release, and is closely related to inflammatory diseases. With the wide application of the P2X7-knockout animal model and specific P2X7 receptor antagonists in inflammatory disease research, P2X7 receptor is emerging as a new target for the treatment of inflammatory diseases. This article will review the recent progress regarding the effect of P2X7 receptor on inflammatory diseases and its mechanism.
Animals ; Cytokines ; metabolism ; Disease Models, Animal ; Inflammation ; metabolism ; Purinergic P2X Receptor Antagonists ; pharmacology ; Receptors, Purinergic P2X7 ; metabolism

Diabetic peripheral neuropathy (DPN), one of the most common chronic complications of diabetes, is characterized by allodynia, hyperalgesia and spontaneous pain. Chinese epidemiological studies have shown that at least 25% diabetic patients suffered from painful DPN, which compromises patients' daily functioning and becomes a major health care problem. Although the pathogenesis of painful DPN is not fully understood and current treatment options are very limited, research in the field has advanced our understanding on the mechanism of painful DPN in the past Decade of Pain Research and Control. This review will mainly focus on evaluation of current diabetic animal models, possible molecular pathways and available therapies, with an emphasis on roles of purinergic receptor and its signaling transduction pathways. Common therapies address one or two DPN symptoms, while others offer wider symptom control, presumably by targeting pathophysiological mechanisms of DPN. Purinergic receptor signaling transduction pathways might become potential targets for treatment for painful DPN.
Animals ; Diabetes Mellitus ; physiopathology ; Diabetic Neuropathies ; physiopathology ; Humans ; Hyperalgesia ; physiopathology ; Pain ; physiopathology ; Receptors, Purinergic P2X ; physiology

Numerous studies have shown that adenosine or adenosine agonists can stimulate angiogenesis. However, the effect of caffeine (a known adenosine receptor antagonist) on angiogenesis has not been previously studied. Accordingly, this study was undertaken to examine the effect of caffeine on angiogenesis and to clarify the mechanism involved. Chick chorioallantoic membrane assays were used to investigate the effect of caffeine on angiogenesis and proliferation assays using human umbilical vein endothelial cells (HUVECs), were used to study its effects on specific aspects of angiogenesis. The expressions of caspase-3 and Bcl-2 were examined by western blotting, immunofluorescence staining was used to identify HUVEC morphological changes, and fluorescence activated cell sorting (FACS) and DAPI staining were used to detect HUVEC apoptosis. Caffeine was found to inhibit blood vessel formation dose-dependently and to inhibit the proliferation of HUVECs time- and dose-dependently. FACS analysis and DAPI staining showed that inhibitory effect of caffeine on HUVEC proliferation was the result of apoptosis and the up-regulation of thrombospondin-1 (TSP-1). Furthermore, TSP-1 levels were down-regulated by NECA but were unaffected by CGS21680, indicating that caffeine regulated TSP-1 expression via adenosine A2B receptor. In addition, caffeine up-regulated caspase-3 and down-regulated Bcl-2 at the protein level. These results suggest that the inhibitory effect of caffeine on angiogenesis is associated, at least in part, with its induction of endothelial cell apoptosis, probably mediated by a caspase-3 dependent mechanism.
Adenosine ; Adenosine-5'-(N-ethylcarboxamide) ; Apoptosis ; Blood Vessels ; Blotting, Western ; Caffeine ; Caspase 3 ; Chorioallantoic Membrane ; Endothelial Cells ; Flow Cytometry ; Fluorescent Antibody Technique ; Glycosaminoglycans ; Human Umbilical Vein Endothelial Cells ; Indoles ; Phenethylamines ; Receptor, Adenosine A2B ; Receptors, Purinergic P1 ; Thrombospondin 1 ; Up-Regulation

The aim of this study is to investigate the effect of isosorbide-5-mononitrate (ISMN) on the electric field stimulation induced sympathetic purinergic vasoconstriction of the rabbit saphenous arterial rings. Isometric vasoconstrictive responses to electric field stimulation and to exogenous noradrenaline and adenosine triphosphate were recorded. We found that the vasoconstrictive responses to electric field stimulation (15 V, 1 ms pulse duration, 2 - 16 Hz) were frequency-dependant in the rabbit saphenous arterial rings, and abolished by tetrodotoxin (0.1 micromol x L(-1)). The alpha1-adrenoceptor antagonist prazosin (1 micromol x L(-1)) did not affect the vascular responses to the electric field stimulation (2 -8 Hz). After a combination treatment with both alpha,beta-meATP (3 micromol x L(-1), desensitizing P2X1 receptors) and prazosin (1 micromol x L(-1)), the vasoconstrictive responses to electric field stimulation were abolished. When the arterial preparation was treated with ISMN (one preparation was exposed to only one concentration of ISMN), ISMN at 0.1 mmol x L(-1) significantly inhibited the vasoconstriction induced by electric stimulation at 8 Hz, 0.3 and 1.0 mmol x L(-1) significantly inhibited the vasoconstrictive responses to electric stimulation at 2 - 16 Hz. The highest concentration of ISMN (1.0 mmol x L(-1)) reduced the vasoconstrictive responses by 46% (2 Hz), 47% (4 Hz), 34% (8 Hz) and 22% (16 Hz), separately. ISMN (0.3 and 1.0 mmol x L(-1)) did not affect the vascular responses to exogenous noradrenaline (0.01-100 micromol x L(-1)) and adenosine triphosphate (1 mmol x L(-1)). It is reasonable to suggest that ISMN inhibits the purinergic vasoconstriction induced by sympathetic nerve stimulation via a prejunctional mechanism.
Adenosine Triphosphate ; analogs & derivatives ; pharmacology ; Adrenergic alpha-Antagonists ; pharmacology ; Animals ; Arteries ; drug effects ; Delayed-Action Preparations ; Electric Stimulation ; Isosorbide Dinitrate ; administration & dosage ; analogs & derivatives ; pharmacology ; Male ; Norepinephrine ; pharmacology ; Prazosin ; pharmacology ; Purinergic P2 Receptor Agonists ; Rabbits ; Receptors, Purinergic P2X ; Vasoconstriction ; drug effects

PURPOSE: To simultaneously monitor electrical discharges in various bladder regions and the external urethral sphincter (EUS) during voiding contractions, and to assess the functional role of myogenic modulation of the lower urinary tract (LUT) by ionotropic purinergic receptors containing the P2X3 subunit. METHODS: Female Sprague-Dawley rats were anesthetized with urethane, and implanted with a suprapubic catheter for open cystometry. Flexible microelectrodes were placed ventrally in the bladder dome, upper bladder, lower bladder, and bladder base, along with the middle section of the exposed EUS. Intravesical P2X3-containing receptors were blocked with AF-323, a specific P2X3-P2X2/3 receptor antagonist. A digital electrophysiology amplifier was used to record electrical and cystometric signals throughout the LUT. RESULTS: Electrical activity in the LUT started before effective voiding contractions. Bladder pressure and electrical waveforms showed consistent out-of-phase activity when compared with the recordings made at the EUS. This pattern was also observed during voiding contractions in the presence of AF-353, supporting the hypothesis that during bladder distension, activation of P2X3-containing receptors is required for voiding contractions. Furthermore, the inhibition of P2X3-containing receptors significantly decreased the amplitude of electrical signals in the urinary bladder, but not the base or EUS. CONCLUSIONS: Our results provide novel information about the regulation of the micturition process by P2X3-containing receptors located in the inner layers of the bladder.
Animals ; Catheters ; Electrophysiology ; Female* ; Humans ; Lower Urinary Tract Symptoms ; Microelectrodes ; Purinergic P2X Receptor Antagonists ; Rats* ; Rats, Sprague-Dawley ; Receptors, Purinergic ; Urethane ; Urethra ; Urinary Bladder* ; Urinary Tract ; Urination*