ARRB2 (β-Arrestin-2) Deficiency Alters Fluid Homeostasis and Blood Pressure Regulation
Natalia M. Mathieu, Pablo Nakagawa, Connie C. Grobe, John J. Reho, Daniel Brozoski, Ko‐Ting Lu, Kelsey K. Wackman, McKenzie L. Ritter, Jeffrey L. Segar, Justin L. Grobe, Curt D. Sigmund
Abstract
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 ( Arrb1 ) and β-arrestin2 ( Arrb2 ) knockout mice were employed to evaluate drinking behavior, and BP was evaluated in Arrb2 -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), Arrb2 -knockout mice exhibited a significant elevation in saline intake with no change in water intake. With DOCA treatment, Arrb2 -knockout mice exhibited a significant increase in both saline and water intake. Although Arrb2 -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 Arrb2 -knockout and C57BL/6 mice with and without DOCA. Arrb2 -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, Arrb2 -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.