P2RY4 and myocardial infarction: NTA experiments were used to determine the concentration and median volume of particles isolated using the Exo-spin kit from plasma samples of WT and P2Y4 KO mice, without MI, 24 h post-MI or 24 h post-MI injected intraperitoneally with exosome inhibitor GW4869 (2.5 μg/g), 1 h before LAD ligation.