We employed a guinea pig model of heart failure (HF) that combines ascending aortic constriction with daily administration of the β-adrenergic agonist isoproterenol (1 mg/kg/day for 1 hour) via an implanted programmable pump. The experimental groups included: 1) Sham-operated controls; 2) ACi (Aortic Constriction + isoproterenol); and 3) ACi-SB (ACi with SB treatment delivered via an implanted osmotic pump at 0.5 mg/kg/day). To investigate the effects of P38 MAPK inhibition on the HF proteome and phosphoproteome, we performed a comprehensive 16-plex Tandem Mass Tag (TMT) analysis across these three groups. Phosphopeptide enrichment was carried out on 80% of the pooled sample using titanium dioxide (TiO2), while the remaining unenriched 20% was utilized for protein expression analysis. A 2D-LC-MS/MS workflow was employed to achieve detailed proteomic and phosphoproteomic profiling.