G protein, phosphorylated-GATA4 and VEGF expression in the hearts of transgenic mice overexpressing β(1)- and β(2)-adrenergic receptors

β(1)- and β(2)-adrenergic receptors (ARs) regulate cardiac contractility, calcium handling and protein phosphorylation. The present study aimed to examine the expression levels of vascular endothelial growth factor A (VEGF-A) and several G proteins, and the phosphorylation of transcription factor GATA binding protein 4 (GATA4), by western blot analysis, using isolated hearts from 6 month-old transgenic (TG) mice that overexpress β(1)AR or β(2)AR. Cardiac contractility/relaxation and heart rate was increased in both β(1)AR TG and β(2)AR TG mouse hearts compared with wild type; however, no significant differences were observed between the β(1)- and β(2)AR TG mouse hearts. Protein expression levels of inhibitory guanine nucleotide-binding protein (Gi) 2, Gi3 and G-protein-coupled receptor kinase 2 were upregulated in both TG mice, although the upregulation of Gi2 was more prominent in the β(2)AR TG mice. VEGF-A expression levels were also increased in both TG mice, and were highest in the β(1)AR TG mice. In addition, the levels of phosphorylated-GATA4 expression were increased in β(1)- and β(2)AR TG mice. In conclusion, the present study demonstrated that cardiac contractility/relaxation and heart rate is increased in β(1)AR TG and β(2)AR TG mice, and indicated that this increase may be related to the overexpression of G proteins and G-protein-associated proteins.