ARRB2 (β-Arrestin-2) Deficiency Alters Fluid Homeostasis and Blood Pressure Regulation.

Background: GPCRs (G protein-coupled receptors) are implicated in blood pressure (BP) and fluid intake regulation. There is a developing concept that these effects are mediated by both canonical G protein signaling and noncanonical β-arrestin mediated signaling, but the contributions of each remain largely unexplored. Here, we hypothesized that β-arrestin contributes to fluid homeostasis and blood pressure (BP) regulation in deoxycorticosterone acetate (DOCA) salt hypertension, a prototypical model of salt-sensitive hypertension.

Methods: Global β-arrestin1 () and β-arrestin2 () knockout mice were employed to evaluate drinking behavior, and BP was evaluated in -knockout mice. Age- and sex-matched C57BL/6 mice served as controls. We measured intake of water and different sodium chloride solutions and BP employing a 2-bottle choice paradigm with and without DOCA.

Results: Without DOCA (baseline), -knockout mice exhibited a significant elevation in saline intake with no change in water intake. With DOCA treatment, -knockout mice exhibited a significant increase in both saline and water intake. Although -knockout mice exhibited hypernatremia at baseline conditions, we did not find significant changes in total body sodium stores or sodium palatability. In a separate cohort, BP was measured via telemetry in -knockout and C57BL/6 mice with and without DOCA. -knockout did not exhibit significant differences in BP before DOCA treatment when provided water alone, or when provided a choice of water and saline. However, -knockout exhibited an increased pressor response to DOCA-salt.

Conclusions: These findings suggest that in salt-sensitive hypertension, ARRB2, but not ARRB1 (β-arrestin 1), might counterbalance the canonical signaling of GPCRs.