AGTR1 and cardiac hypertrophy: It is also noteworthy that cardiac hypertrophy has been shown associated with increased concentration of intracellular Ca2+ due to the activation of the AT1R. In this regard, AT1R -Gq/11-phospholipase Cβ (PLCβ) coupling has been reported to produce IP3, which activates IP3 receptor and release Ca2+ from the sarcoplasmic reticulum.