Hypertensive left ventricular hypertrophy: Relation to β-adrenergic receptor kinase-1 (βARK1) in peripheral lymphocytes

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Abstract

Background: Left ventricular hypertrophy (LVH) is associated with increased cardiovascular risk and altered sympathetic regulation in hypertension. Objectives: To determine whether the level of β-adrenergic receptor kinase-1 (βARK1) in lymphocytes is related to LVH in patients with hypertension. Methods: Forty-nine patients with untreated essential hypertension were recruited to the study and classified into two groups: left ventricular hypertrophy (LVH: left ventricular mass index ≥ 134 g/m2 in men and ≥ 110 g/ m2 in women; ages 52.4 ± 12.8 years, n = 25) and non-LVH (NLVH: left ventricular mass index < 134 g/m2 in men and < 110 g/m2 in women; ages 50.8 ± 13.1 years, n = 24). Lymphocytes were isolated from patients and quantitative-competitive reverse transcriptase-polymerase chain reaction (RT-PCR) and immunoblotting were used to estimate the expression of βARK1 in the lymphocytes. G-protein-coupled receptor kinase activity was assessed by rhodopsin phosphorylation assay. Results: The expression of βARK1 in lymphocytes was greater in the LVH group than in the NLVH group (0.0069 ± 0.002 ng compared with 0.0048 ± 0.0017 ng, P < 0.01) and correlated well with left ventricular mass index (r = 0.527, P < 0.001) and relative wall thickness (r = 0.627, P < 0.001). The concentration of βARK1 protein in lymphocytes from individuals with LVH was increased two-fold compared with that in the NLVM group (both n = 7). Lymphocyte G-protein-coupled receptor kinase activity from LVH was enhanced 1.7-fold compared with NLVH (1.03 ± 2.16 and 1.79 ± 1.87 pmol phosphate/min per mg protein, respectively; P < 0.05, n = 7 for each group). Conclusions: The concentration of βARK1 in lymphocytes is greater in hypertensive individuals with LVH than in those without LVH and parallels the degree of hypertrophy. Generalized alterations in β-adrenergic signalling, including βARK1, could be a major contributory factor in the development of LVH in hypertension, and the concentration of βARK1 in lymphocytes can reflect the development of LVH in a patient with hypertension.

Original languageEnglish
Pages (from-to)1025-1032
Number of pages8
JournalJournal of Hypertension
Volume22
Issue number5
DOIs
StatePublished - May 2004
Externally publishedYes

Keywords

  • Cardiac hypertrophy
  • Hypertension
  • Lymphocyte
  • β-adrenergic receptor kinase-1

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