P2RX4 and autosomal recessive polycystic kidney disease: Although no study has investigated the effect of P2X4R antagonists on ARPKD, one study showed that knocking out P2X7R in PCK rats slowed the cyst's growth but not the formation of new cysts, increased epithelial sodium channel activity, and restored impaired channel function (Arkhipov et al., 2019).