Desensitisation of the β-adrenergic (βAR) response is typically seen in heart failure (HF), caused by decreased β1AR expression and β1AR uncoupling. β-blockers are routinely used in treatment for left ventricular (LV) HF but are not currently recommended for patients with right ventricular (RV) HF induced by pulmonary artery hypertension (PAH). We have previously shown that treatment with the β1AR antagonist metoprolol can improve survival and increase cardiac myocyte responses to selective β1AR stimulation in a rat model of PAH. However, it is unclear how these improvements in function are linked to changes in expression of key signalling proteins. Membrane scaffolds such as caveolin 3 (Cav 3) help to create discrete microdomains allowing for effective intracellular signalling. Disruptions to these could perturb downstream signalling. Here we examine how the expression and membrane distribution of β1AR signalling components and caveolar proteins change in RV HF and if this is recovered with β-blocker treatment. Male Wistar rats (190-230g) received an i.p. injection of saline (CON group) or 60 mg/kg of monocrotaline(MCT). MCT animals were given metoprolol (10 mg/kg; MCT+BB group) or placebo (MCT group) daily by oral administration from 15 days post injection. MCT induces RV hypertrophy which progresses to RV HF by 21-28 days post-injection. MCT+BB and CON animals were time-matched to MCT animals. Western blotting was used to measure protein expression and protein membrane distribution (using a discontinuous sucrose gradient) in myocardial homogenates1. For fractionated samples, loading was standardised between groups to the total protein across all fractions. RV homogenate showed a significant reduction in total β1AR, adenyl cyclase (AC), Cav 3 and cavin 1 in the MCT animals compared with the control (P<0.05, n=6, one-way ANOVA), with no difference between CON and MCT+BB (n=6). Increased total Gαi3 and G protein coupled receptor kinase 2 (GRK2) was observed in the MCT RV compared to CON and MCT+BB (P<0.05). The majority of Cav 3 and AC was found within the buoyant caveolae-containing fractions (CF), while β1AR and Gαi3 were more evenly distributed. β1AR was redistributed from CF to non-CF in MCT (P<0.05). Cav 3 and AC were significantly decreased in the CF of the MCT animals (P<0.05 vs. CON, n=4, RM one-way ANOVA) with no difference in the non-CF. There was no difference between CON and MCT+BB (n=4). In MCT, changes in expression and membrane distribution of β1AR signalling components and caveolar proteins suggest a reduction in caveolae and β1AR-AC coupling, which is partially recovered by BB treatment. Targeted HF treatments for caveolar and membrane structure could help further improve function. These results highlight the importance of linking protein distribution/organisation with function within the cardiac myocyte.