Increase in expression of P2X1 receptors in the atria of patients suffering from dilated cardiomyopathy.

P2X1 receptors are ATP-sensitive ligand-gated cation-selective channels abundant in smooth muscle tissues such as bladder and vas deferens. They have also been detected in the central and peripheral nervous system and in heart tissue. We have earlier reported distinct changes in the expression of the PX1 subtype of P2X receptors in hearts of patients suffering from dilated cardiomyopathy (DCM). The study was, however, based on Western blots from only five DCM samples and three control hearts. Moreover, the antibody was directed against a peptide derived from the sequence of rat P2X1. In the present project we have examined larger groups of both DCM and control hearts (n = 14 and 11, respectively). Furthermore, the antibody used in this paper differs significantly from the one used in our previous report. The present antibody was raised against an 18-residue peptide sequence (Lys 68-84 Val) derived from the human P2X1 sequence. Most of the label in the Western blots was concentrated over a triplet of bands migrating with an apparent Mr of about 45,000. Quantitative densitometry indicated that this band was more strongly expressed (by approximately 80%) in DCM hearts compared with the controls.