ADRB1 and type 1 diabetes mellitus: Another evidence in favor of compensatory redistribution of β1-AR and β2-AR-mediated signaling pathways in the diabetic heart is the fact that in the heart of 14-week-STZ diabetic rats the contents of β1-AR protein and β1-AR mRNA were decreased to 35% and 45%, respectively, whereas the decrease of the maximum chronotropic response of the right atria to β1-AR agonists exceeded 70% of that in control, indicating an increase of the contribution of β2-AR-signaling to β-AR-mediated chronotropic effects in T1DM [86, 103].