It was shown that in the right atrium of swine with STZ-induced DM the density of β-AR was 14% lower, and the forskolin- and GppNHp-stimulated AC activities were reduced by 34 and 23%, respectively, whereas the basal and isoproterenol-stimulated AC activities as well as the content of Gs and Gi proteins did not change. Here, GNAI1 is linked to diabetes mellitus.