The present study was designed to evaluate the binding and functional characterization of A2A and A3 adenosine receptors in human neutrophils exposed to low frequency, low energy, pulsing electromagnetic fields (PEMFs). Saturation binding experiments on A2A and A3 adenosine receptors revealed a single class of binding sites with similar affinity in control and in PEMF-treated human neutrophils (KD=1.050.10 and 1.080.12 nM for A2A receptors and KD=2.360.16 and 2.450.15 nM for A3 receptors, respectively). PEMFs treatment revealed that the A2A and A3 receptor density was statistically increased (Bmax=12610 and 21515* fmol mg-1 protein and Bmax=45118 and 73625* fmol mg-1 protein, respectively, *, P<0.01). In the adenylyl cyclase assays the A2A agonists, HE-NECA and NECA increased cAMP accumulation in untreated human neutrophils with an EC50 value of 43 (40-47) and 255 (228-284) nM, respectively. The capability of the examined compounds to stimulate cAMP levels in human neutrophils was increased after PEMF exposure with an EC50 value of 10 (8-13)* and 61 (52-71)* nM, respectively, *, P<0.01. In the superoxide anion production assays examined agonists inhibited the generation of O2- in untreated human neutrophils with an EC50 value of 3.6 (3.1-4.2) and of 23 (20-27) nM, respectively. In PEMF-treated human neutrophils, the same compounds show an EC50 value of 1.6 (1.2-2.1)* and of 6.0 (4.7-7.5)* nM, respectively, *, P<0.01. Similarly, typical A3 agonists such as Cl-IB-MECA and IB-MECA were able to inhibit cyclic AMP accumulation and superoxide anion production. The potencies of Cl-IB-MECA and IB-MECA were statistically increased after exposure to PEMFs. These data indicate in human neutrophils treated with PEMFs the presence of significant alterations in the A2A and A3 adenosine receptor density and functionality. In summary, these results should serve as an impetus for further investigation of the pharmacological changes in the adenosine receptors and PEMF treatment. From a clinical point of view a clarification of the potential effects of PEMFs facilitate the development of alternative treatments or the elaboration of novel promising therapeutic tools.
Effect of low frequency electromagnetic fields on A2A and A3 adenosine receptors in human neutrophils.
BOREA, Pier Andrea;VARANI, Katia;GESSI, Stefania;MERIGHI, Stefania;CATTABRIGA, Elena;VINCENZI, Fabrizio;
2005
Abstract
The present study was designed to evaluate the binding and functional characterization of A2A and A3 adenosine receptors in human neutrophils exposed to low frequency, low energy, pulsing electromagnetic fields (PEMFs). Saturation binding experiments on A2A and A3 adenosine receptors revealed a single class of binding sites with similar affinity in control and in PEMF-treated human neutrophils (KD=1.050.10 and 1.080.12 nM for A2A receptors and KD=2.360.16 and 2.450.15 nM for A3 receptors, respectively). PEMFs treatment revealed that the A2A and A3 receptor density was statistically increased (Bmax=12610 and 21515* fmol mg-1 protein and Bmax=45118 and 73625* fmol mg-1 protein, respectively, *, P<0.01). In the adenylyl cyclase assays the A2A agonists, HE-NECA and NECA increased cAMP accumulation in untreated human neutrophils with an EC50 value of 43 (40-47) and 255 (228-284) nM, respectively. The capability of the examined compounds to stimulate cAMP levels in human neutrophils was increased after PEMF exposure with an EC50 value of 10 (8-13)* and 61 (52-71)* nM, respectively, *, P<0.01. In the superoxide anion production assays examined agonists inhibited the generation of O2- in untreated human neutrophils with an EC50 value of 3.6 (3.1-4.2) and of 23 (20-27) nM, respectively. In PEMF-treated human neutrophils, the same compounds show an EC50 value of 1.6 (1.2-2.1)* and of 6.0 (4.7-7.5)* nM, respectively, *, P<0.01. Similarly, typical A3 agonists such as Cl-IB-MECA and IB-MECA were able to inhibit cyclic AMP accumulation and superoxide anion production. The potencies of Cl-IB-MECA and IB-MECA were statistically increased after exposure to PEMFs. These data indicate in human neutrophils treated with PEMFs the presence of significant alterations in the A2A and A3 adenosine receptor density and functionality. In summary, these results should serve as an impetus for further investigation of the pharmacological changes in the adenosine receptors and PEMF treatment. From a clinical point of view a clarification of the potential effects of PEMFs facilitate the development of alternative treatments or the elaboration of novel promising therapeutic tools.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
