Figure 5.

Expression pattern of β‐ARs. A, Representative immunoblots and densitometric analysis of (B) the β₁‐AR, (C) the β₂‐AR and (D) the β₃‐AR. Remodeling and intracellular coupling of cardiac β‐ARs. E, Representative blots and densitometric data of the (F) phosphorylated and (G) total GRK2 protein. H, The pGRK2 to β₁‐AR ratio was calculated for each animal, and group means were expressed as fold change of Sham. I, The mRNA expression of GRK2 was analyzed in left ventricular tissue and normalized to HPRT. J, β‐Arrestin1/2, also critically involved in β‐AR coupling, was exclusively upregulated in IPoC hearts. K, Na⁺/K⁺ ATPase was determined as a surrogate marker for the membrane density. Immunoblot bands were normalized to GAPDH and expressed as a percentage of Sham. Data are means±SD of n=6 hearts. *P≤0.05 vs Sham, ^# P≤0.05 vs IR. AR indicates adrenergic receptor; arr, arrestin; GAPDH, Glyceraldehyde 3‐phosphate dehydrogenase; GRK2, G protein‐coupled receptor kinase 2; HPRT, hypoxanthine‐guanine phosphoribosyltransferase; IPC, ischemic preconditioning; IPoC, ischemic postconditioning; IR, ischemia/reperfusion; p‐GRK2, phosphorylated GRK2.