AGTR1 and Hypertension: In the present study, we use specific G protein or β-arrestin-biased GPCR agonists and knockout mouse models to investigate the role of β-arrestin or G protein subtype-mediated GPCR signalling in catecholamine secretion after angiotensin II receptor type 1 (AT1R) activation, which may mimic clinical conditions, such as hypertension or response to severe haemorrhage19.