Increased β2-adrenergic vasorelaxation at the early phase of endotoxemic shock in rats.
Vascul Pharmacol 2015;
72:181-9. [PMID:
25921926 DOI:
10.1016/j.vph.2015.04.007]
[Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 03/09/2015] [Accepted: 04/20/2015] [Indexed: 12/15/2022]
Abstract
BACKGROUND AND PURPOSE
The early management of the cardiovascular dysfunction of septic shock is critical as it is associated with a poor outcome. Although the use of catecholamines is a common therapy in this syndrome, no data are available on the involvement of β-adrenoceptor (β-AR) subtypes and only few studies report an alteration of β-adrenergic-induced vasodilation in septic shock. The purpose of the study was to evaluate vascular β1, β2 and β3-AR expression and function in an endotoxemic rat model.
EXPERIMENTAL APPROACH
Endotoxemia was induced in rats by intravenous injection of lipopolysaccharide (LPS). β1, β2 and β3-AR mRNA expression was evaluated by RT-PCR in aorta and vascular β1, β2 and β3-AR responses were determined on conducting (aorta) and/or resistance (mesenteric and renal) arteries by constructing relaxation curves in response to different β-AR agonists.
RESULTS
The maximal effect of isoproterenol decreased by 31 to 61% in the three vascular beds of LPS-treated rats compared to controls. In aortas from LPS-treated rats, β1 and β3-AR mRNA expression was decreased and associated to a reduced β1 and β3-induced vasodilation. Conversely, albeit β2-AR mRNA was unchanged, the maximal β2-AR-induced vasodilation increased by 49% in aortas from LPS-treated rats compared to controls. This increase was not affected by endothelium removal but was abolished in the presence of a β2-AR antagonist or an adenylate cyclase inhibitor.
CONCLUSIONS
In endotoxemia, β2-AR vasodilation was increased by a potential recruitment of β2-AR located on smooth muscle cells. This study suggests that vascular β2-AR should be a putative new therapeutic target in septic shock.
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