A2B adenosine receptor is involved in the control of mast cell degranulation, interleukin-8 synthesis and cell growth. A2B adenosine receptor antagonists may serve as novel drugs for asthma, Alzheimer' s disease, cystic fibrosis and type-II diabetes. Therefore, seeking for the highly selective A2B adenosine receptor antagonists has been one of great interest. The molecular basis, structure-activity relationship of selective A2B adenosine receptor antagonists and their interactions with A2B adenosine receptor were reviewed.
Adenosine ; pharmacology ; Adenosine A2 Receptor Antagonists ; Adenosine A3 Receptor Antagonists ; Adenosine-5'-(N-ethylcarboxamide) ; pharmacology ; therapeutic use ; Animals ; Anti-Asthmatic Agents ; therapeutic use ; Asthma ; drug therapy ; Humans ; Pulmonary Artery ; drug effects ; Structure-Activity Relationship ; Xanthines ; pharmacology

AIMTo clarify the relationship between bicarbonate and cAMP in the promoting effects on the sperm agglutination.

METHODSSpermatozoa were collected from mature boars, washed and resuspended in a modified Krebs-Ringer HEPES lacking calcium chloride (mKRH). The sperm suspensions were incubated in a water bath (38.5 degrees C) for 60 min and then the percentage of head-to-head agglutinated spermatozoa was determined.

RESULTSSupplementation of the mKRH with sodium bicarbonate (5-10 mM) significantly raised the percentage of head-to-head agglutinated spermatozoa in the samples. The addition of selective inhibitors for calcium/calmodulin-dependent phosphodiesterases (type 1: 8-methoxymethyl-IBMX and vinpocetine, 25-50 micro M) or for cAMP-specific phosphodiesterases (type 4: Ro20-1724 and rolipram, 25-50 microM) enhanced the effect of bicarbonate on sperm agglutination as highly as did the addition of non-selective inhibitors for phosphodiesterases (IBMX and papaverine, 25-50 microM). A calmodulin antagonist (W-7, 2 microM), that potentially blocks the stimulator of the calcium/calmodulin-dependent phosphodiesterases, significantly enhanced the effect of bicarbonate on sperm agglutination. Moreover, a phosphodiesterase-resistant cAMP analogue (cBiMPS, 0.1 mM) markedly induced agglutination in more spermatozoa (76%) after the incubation without bicarbonate and phosphodiesterase inhibitors than did a less potent cAMP analogue (dibutyryl cAMP, 1 mM) (21%), while three kinds of cGMP analogues (0.1-1 mM) had no effect on sperm agglutination. In addition, a cAMP antagonist (Rp-cAMPS, 1 mM) significantly reduced the sperm agglutination resulting from the actions of bicarbonate and IBMX. On the other hand, the effect of bicarbonate was abolished by a change of incubation temperature from 38.5 degrees C to 25 degrees C.

CONCLUSIONThese findings demonstrate that the bicarbonate-induced agglutination of boar spermatozoa is controlled via the cAMP-mediated, temperature-dependent signaling cascade. This cascade is suppressed by the action of the phosphodiesterase (at least types 1 and 4).

1-Methyl-3-isobutylxanthine ; pharmacology ; Animals ; Bucladesine ; pharmacology ; Cyclic AMP ; physiology ; Cyclic GMP ; analogs & derivatives ; pharmacology ; physiology ; Male ; Papaverine ; pharmacology ; Purinergic P1 Receptor Antagonists ; Sodium Bicarbonate ; pharmacology ; Sperm Agglutination ; drug effects ; physiology ; Sperm Head ; drug effects ; physiology ; Swine ; Theophylline ; analogs & derivatives ; pharmacology

This study is to examine the sedative, hypnotic and anticonvulsive effects of an adenosine analogue, WS090501. The spontaneous locomotor activity was recorded by open field equipment, and the EEG of rats was recorded by polyphysiograph. Pentylenetetrazol (PTZ)-induced seizure model was used. The spontaneous locomotor activity was decreased by WS090501 at various doses (0.06, 0.13, and 0.25 mg x kg(-1)), and the decreasing rate was 28.4%, 47.1% and 61.2% respectively. Furthermore, the effect of WS090501 on spontaneous locomotor activity of mice can be antagonized by DPCPX, a selective adenosine A1R antagonist, but cannot be antagonized by SCH58261, a selective adenosine A2AR antagonist. The NREM sleep was significantly increased by WS090501 (0.05 and 0.2 mg x kg(-1)), and the increasing rate was 27.6% and 102.8%, respectively, at 6th hour after administration. The REM sleep decreased significantly at the higher dose. PTZ induced serious convulsion in mice. The latency of convulsion was prolonged, and the number of seizure and mortality decreased after administration of WS090501. These results show that WS090501 has potent sedative, hypnotic and anticonvulsive effects, which may be mediated through adenosine A1R.
Adenosine ; analogs & derivatives ; antagonists & inhibitors ; pharmacology ; Adenosine A1 Receptor Antagonists ; pharmacology ; Adenosine A2 Receptor Antagonists ; pharmacology ; Animals ; Anticonvulsants ; antagonists & inhibitors ; pharmacology ; Convulsants ; Electroencephalography ; Hypnotics and Sedatives ; antagonists & inhibitors ; pharmacology ; Male ; Mice ; Mice, Inbred ICR ; Motor Activity ; drug effects ; Pentylenetetrazole ; Pyrimidines ; pharmacology ; Rats ; Rats, Wistar ; Seizures ; chemically induced ; prevention & control ; Sleep ; drug effects ; Triazoles ; pharmacology ; Xanthines ; pharmacology

AIMTo study the effect of AMP579 and adenosine on potassium ionic (K+) or sodium ionic (Na+) channels and to elucidate ionic mechanisms underlying negative inotropic and antiarrhythmic effects of AMP579 and adenosine.

METHODSIonic channel currents of rat and guinea pig ventricular myocytes were recorded by patch clamp technique in whole-cell configuration.

RESULTSAdenosine showed a stronger activating effect on transient outward K+ current (I(to)) than AMP579, EC50 of adenosine and AMP579 were 2.33 and 8. 32 micromol x L(-1), respectively (P < 0.05). An adenosine A1 receptor blocker, 1,3-dipropyl-8-cyclopentylxanthine (PD116948), can abolish the effects of AMP579 and adenosine on I(to), demonstrating that the effect is mediated by adenosine A1 receptor. Adenosine exerted a more obvious inhibitory effect on delayed rectifier K+ current (IK) than AMP579. IC50 of adenosine and AMP579 were 1.21 and 2.31 micromol x L(-1), respectively (P < 0.05). AMP579 had a more powerful inhibitory effect on inward rectifier K+ current (IK1) than adenosine. IC50 of AMP579 and adenosine were 4.15 and 20.7 micromol x L(-1), repectively (P < 0.01). AMP579 and adenosine exerted a similar inhibitory effect on fast inward Na+ current (INA), IC50 of AMP579 and adenosine were 9.46 and 6.23 micromol x L(-1), respectively (P > 0.05).

CONCLUSIONAdenosine showed a stronger activating effect on I(to) than AMP579, however, the mechanism of AMP579 and adenosine activating I(to) was mediated by adenosine A1 receptor. AMP579 has a more powerful inhibitory effect on IK1, and less inhibitory effect on IK than adenosine. Both drugs have a similar inhibitory effect on INa. The negative inotropic and antiarrhythmic effects are related to these ionic mechanisms.

Adenosine ; chemistry ; pharmacology ; Adenosine A1 Receptor Antagonists ; Adenosine A2 Receptor Antagonists ; Animals ; Dose-Response Relationship, Drug ; Electric Stimulation ; Guinea Pigs ; Heart Ventricles ; cytology ; Imidazoles ; chemistry ; pharmacology ; Male ; Membrane Potentials ; drug effects ; Molecular Structure ; Myocytes, Cardiac ; cytology ; drug effects ; physiology ; Potassium Channels ; physiology ; Potassium Channels, Inwardly Rectifying ; physiology ; Pyridines ; chemistry ; pharmacology ; Rats ; Rats, Wistar ; Sodium Channels ; physiology ; Theobromine ; analogs & derivatives ; pharmacology ; Xanthines ; pharmacology

Adenosine is a metabolite produced abundantly in the tumor microenvironment, dampening immune response in inflamed tissues via adenosine A2A receptor (A2AR) which is widely expressed on immune cells, inhibiting anti-tumor immune response accordingly. Therefore, blocking adenosine signaling pathway is of potential to promote anti-tumor immunity. This review briefly introduces adenosine signaling pathway, describes its role in regulating tumor immunity and highlights A2AR blockade in cancer therapy. Prospective anti-tumor activity of adenosine/A2AR inhibition has been revealed by preclinical data, and a number of clinical trials of A2AR antagonists are under way. Primary results from clinical trials suggest that A2AR antagonists are well tolerated in cancer patients and are effective both as monotherapy and in combination with other therapies. In the future, finding predictive biomarkers are critical to identify patients most likely to benefit from adenosine pathway blockade, and further researches are needed to rationally combine A2AR antagonists with other anti-tumor therapies.
.
Adenosine/therapeutic use* ; Adenosine A2 Receptor Antagonists/therapeutic use* ; Humans ; Lung Neoplasms ; Receptor, Adenosine A2A/metabolism* ; Tumor Microenvironment

Adenosine receptors (AR) play an important role in the regulation processes for body temperature and vigilance states. During our previous studies, we noticed that aminophylline (a non-selective, blood-brain-barrier penetrably AR antagonist) could attenuate the effects of YZG-330 [(2R,3S,4R,5R)-2-(hydroxymethyl-5-(6-(((R)-1-phenylpropyl)amino)-9H-purin-9-yl)tetrahydrofuran-3, 4-diol] on lowering the body temperature. Hereby, we focused ourselves on the character of thermal regulation effect of YZG-330 in mice and tried to specify the receptor subtype via giving typical adenosine receptor antagonists. The results showed that both of the magnitude and lasting time of the effect that YZG-330 played on decreasing body temperature are in a dose-dependent manner: within the next 3 hour after intragastric administration (ig) of 0.25, 1 or 4 mg . kg-1 YZG-330, the extreme values on body temperature decreasing were (1.2 ± 0.3) °C, (3.6 ± 0.4) °C (P<0.001) and (7.4±0.5) °C (P<0.001), separately; whereas the duration that body temperature below 34 °C were 0, (10±5) and (153±4) min, separately. Adenosine A1 receptor (A1R) antagonist (DPCPX) could effectively reverse YZG-330's effect on decreasing body temperature, with intraperitoneal administration of DPCPX (5 mg . kg-1) 20 min prior than YZG-330 (4 mg.kg-1, ig), the extreme value on body temperature decreasing was (3.5 ± 0.7) °C (P<0.001), the duration that body temperature below 34 °C was (8±6) min (P<0.001). However, adenosine A2a receptor antagonist, SCH-58261, did not show any influence on the effects of YZG-330 at all. Combined with the fact that 8-SPT (a non-selective, blood-brain-barrier impenetrably AR antagonist) did not reverse the effect of YZG-330, we come to the conclusion that central-adenosine A, receptor plays a significant role on the thermal regulation effect of YZG-330.
Adenosine ; analogs & derivatives ; pharmacology ; Adenosine A1 Receptor Antagonists ; pharmacology ; Animals ; Body Temperature Regulation ; drug effects ; Mice ; Pyrimidines ; pharmacology ; Receptor, Adenosine A1 ; physiology ; Triazoles ; pharmacology ; Xanthines ; pharmacology

This study is to investigate the effect of compound B2 on the damage of PC12 cells induced by serum deprivation and to explore its related mechanisms. The binding characteristics of B2 to rat striatum adenosine A2A receptor was studied by radioligand 3H-MSX-2 binding assay. Cell viability was detected by MTT assay. ROS formation was measured after DCFDA fluorescent staining. B2 has affinity to rat adenosine A2A receptor (K1 = 0.37 micromol x L(-1)). B2 remarkably increased PC12 cell survival rate in serum deprivation-induced PC12 cells. The percentage of serum deprivation-induced death of PC12 was 49.6%, and the treatment of B2 (0.1-100 micromol x L(-1)) increased the cell viability to 63.3%, 74.9%, 86.3% and 88.1%, respectively. Adenosine A2A receptor antagonist SCH 58261 could significantly block the protective effect of B2. The cell viability with 0.1 micromol x L(-1) SCH 58261 decreased by 16.1%, 24.0% and 19.8%, in the presence of B2 (0.1-10 micromol x L(-1)). Serum deprivation-induced ROS formation was 3.5 times more than that of control group, and treatment with B2 significantly and dose-dependently inhibited ROS over-formation. The protective effect of B2 may be related with adenosine A2A receptor. Decrease of serum-deprivation induced ROS formation may also be one of the mechanisms.
Adenosine ; analogs & derivatives ; metabolism ; pharmacology ; Adenosine A2 Receptor Antagonists ; pharmacology ; Animals ; Cell Survival ; drug effects ; Corpus Striatum ; metabolism ; Culture Media, Serum-Free ; Female ; Male ; PC12 Cells ; Pyrimidines ; pharmacology ; Rats ; Rats, Wistar ; Reactive Oxygen Species ; metabolism ; Receptor, Adenosine A2A ; metabolism ; Triazoles ; pharmacology

Cardio-renal syndromes are disorders of the heart and kidney wherein acute or long-term dysfunction in one organ may induce acute or long-term dysfunction of the other. Because of this complex organ interaction, management of cardiorenal syndrome must be tailored to the underlying pathophysiology. Clinical guidelines exist for the treatment of heart failure or renal failure as separate conditions. Thus far, however, there has been no consensus about managing patients with cardio-renal and reno-cardiac syndromes. Pharmacologic treatment remains a controversial subject. Standard cardiac drugs such as diuretics and inotropes may have limited effect because resistance often develops after long-term use. Recent studies of patients with acute cardio-renal syndromes have focused on newer therapies, including phosphodiesterase inhibitors, vasopressin antagonists, adenosine A1 receptor antagonists, and renal protective dopamine. Initial clinical trials of these agents have shown encouraging results in some patients with heart failure, but have failed to demonstrate a clear superiority over more conventional treatments. Similarly, the benefits of diuretics, aspirin, erythropoietin agents, and iron supplements for management of chronic cardiorenal syndromes are unknown.
Adenosine A1 Receptor Antagonists ; Aspirin ; Cardio-Renal Syndrome ; Consensus ; Diuretics ; Dopamine ; Erythropoietin ; Heart ; Heart Failure ; Humans ; Iron ; Kidney ; Phosphodiesterase Inhibitors ; Renal Insufficiency ; Vasopressins

The effects of injection of adenosine into the renal artery on multi- and single-unit spontaneous discharges of renal afferent nerve fibers were investigated in anesthetized rabbits. The results obtained are as follows: (1) injection of 50, 100, and 200 nmol/kg adenosine into the renal artery increased the renal afferent nerve activity (ARNA) in a dose-dependent manner with unchanged arterial pressure; (2) pretreatment with 8-cyclopenthl-1,3-dipropylxanthine (DPCPX, 160 nmol/kg), an adenosine A1 receptor antagonist, partly abolished the effect of adenosine; and (3) pretreatment with a nitric oxide synthase inhibitor N(omega)-nitro-L-arginine methylester (L-NAME, 0.1 mmol/kg) significantly enhanced the ARNA response to adenosine. The results suggest that injection of adenosine into the renal artery activates ARNA via adenosine receptors in anesthetized rabbits and that nitric oxide may be involved in regulating the activity of renal sensory nerve fibers as an inhibitory neurotransmitter.
Adenosine ; pharmacology ; Adenosine A1 Receptor Antagonists ; Afferent Pathways ; drug effects ; physiology ; Animals ; Dose-Response Relationship, Drug ; Electrophysiology ; Female ; Injections, Intra-Arterial ; Kidney ; innervation ; Male ; Nerve Fibers ; drug effects ; physiology ; Nitric Oxide ; physiology ; Rabbits ; Renal Artery ; Xanthines ; pharmacology

AIMTo observe the effect of adenosine A, receptor antagonist on synaptic transmission in the dentate gyrus of hippocampus and its relations with NMDA receptor.

METHODSUsing electrophysiological technique to record the long-term potentiation (LTP), the relation between selective adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) and NMDA receptor agonist/antagonist, in both basic synaptic transmission and 200 Hz high-frequency stimulation (HFS) induced LTP of the dentate gyrus of hippocampus in anesthetized rats, was studied.

RESULTSDPCPX (6 mg x L(-1), 5 microL, icv) or NMDA (0.2 mg x L(-1), 5 microL, icv) was shown not to affect the synaptic transmission in the dentate gyrus in rats. DPCPX was found not to affect the keeping of LTP induced by HFS after icv NMDA. But the basic synaptic transmission and the magnitude of LTP induced by HFS in the dentate gyrus after icv NMDA could be enhanced significantly by icv DPCPX in advance. DPCPX could not affect the magnitude of LTP inhibited by AP5 (0.5 mg x L(-1), 5 microL) NMDA receptor antagonist, but the inhibitory effect of AP5 on LTP could be antagonized by icv DPCPX in advance.

CONCLUSIONThe selective adenosine A1 receptor antagonist DPCPX could not affect the synaptic transmission in the dentate gyrus of hippocampus, but could significantly enhance the effect of NMDA receptor in both basic synaptic transmission and HFS induced LTP in the dentate gyrus of hippocampus in anesthetized rats.

2-Amino-5-phosphonovalerate ; pharmacology ; Adenosine A1 Receptor Antagonists ; Animals ; Dentate Gyrus ; drug effects ; physiology ; Long-Term Potentiation ; drug effects ; Male ; N-Methylaspartate ; pharmacology ; Rats ; Rats, Wistar ; Receptors, N-Methyl-D-Aspartate ; antagonists & inhibitors ; Synaptic Transmission ; drug effects ; Xanthines ; pharmacology