P2X7 receptor antagonism attenuates the hypertension and renal injury in Dahl salt-sensitive rats

The P2X(7) receptor is a ligand-gated ion channel activated by extracellular ATP, and a common genetic variation in the P2X(7) gene significantly affects blood pressure. P2X(7) receptor expression is associated with renal injury and some inflammatory diseases. Brilliant blue G (BBG) is a selective rat P2X(7) receptor antagonist. In this study, to test whether BBG has protective effects on salt-sensitive hypertension and renal injury, Dahl salt-sensitive (DS) rats fed an 8% NaCl diet were i.p. injected with BBG (50 mg kg(-1) per day) for 4 weeks. We also tested another P2X(7) receptor antagonist, namely A-438079 (100 mg kg(-1) per day), for 7 days. We found that P2X(7) antagonism markedly attenuated salt-sensitive hypertension, urinary protein or albumin excretion, renal interstitial fibrosis and macrophage and T-cell infiltration in the DS rats, and significantly improved creatinine clearance. In an in vitro experiment using macrophages, we showed that lipopolysaccharide (LPS)-primed macrophages from the DS rats released more interleukin-1 beta in response to BzATP, a P2X(7) receptor agonist, than the macrophages from Lewis rats, possibly due to higher P2X(7) expression in the DS rats. In conclusion, in vivo blockade of P2X(7) receptors attenuated salt-sensitive hypertension and renal injury in the DS rats. Thus, P2X(7) appears to be responsible for a vicious cycle of salt-sensitive hypertension and renal injury in the DS rats, through higher expression in the immune cells. Furthermore, P2X(7) antagonists can prevent the development of salt-sensitive hypertension and renal injury, thus confirming that the P2X(7) receptor is an important therapeutic target. Hypertension Research (2012) 35, 173-179; doi:10.1038/hr.2011.153; published online 15 September 2011