Given the unclear role of P2X2 receptors in heart failure and possible presence of P2X2/X3 heterodimeric receptors [6], it is likely that a high concentration of P2X3 receptor antagonist AF-353 applied in the in situ preparation may also act at P2X2 receptors and result in non-specific effects, which could partially contribute to the therapeutic effect. This evidence concerns the gene XPR1 and heart failure.