Fig. 1.

A_2a adenosine receptor (AR) modulation of the A₁AR antiadrenergic effect. The A₁AR-mediated antiadrenergic response was evaluated using wild-type (WT) and A_2aAR knockout (A_2aKO) mouse hearts. A: left ventricular systolic pressure (LVSP). B: +dP/dt. C: −dP/dt. Data are expressed as percent increases above baseline values after isoproterenol (Iso) stimulation. For A₁AR activation, hearts were preincubated with 200 nM of the A₁AR agonist 2-chloro-N-cyclopentyladenosine (CCPA) for 5 min before Iso stimulation. Data are means ± SE; n ≥ 5 hearts/group. *P < 0.05 vs. Iso; #P < 0.05, A_2aKO mice with CCPA + Iso vs. WT mice with CCPA + Iso.