Association between betaARK1 Level of Circulating Mononuclear Leukocytes and Left Ventrcular mass in Non-treated Hypertensive Patients

Choi, Bong Ryong; Kim, Eun Ji; Lee, Ji Eun; Yun, Ji Cheol; Nam, Jung Hee; Park, Seong Ji; Hwang, Jin Yong; Choi, Dong Ju; Seo, Bong Gwan

Abstract

BACKGROUND: Beta-adrenergic receptor Kinase 1(betaARK1) is a serine/threonine kinase attached, which inhibits the coupling of beta-adrenergic receptor with G-protein. Myocardial betaARK1 level is usually elevated in heart failure and hypertrophy, but it is not known whether the circulating betaARK1 level is related with the degree of cardiac hypertrophy. This study was performed to evaluate the association of the betaARK1 level in circulating mononuclear leukocytes(MNL) in untreated hypertension with left ventricular mass in hypertensive patients. Method: Nineteen non-treated hypertensive patients were included for this study. High blood pressure was confirmed when systolic BP is over 150 mmHg or diastoli BP is over 95 mmHg. Echocardiography was performed to evaluate the degree of hypertrophy by measuring the left ventricular mass index(LVMI) and relative wall thickness(RWT), and test the LV function by measuring the ejection fraction(EF) according to ASE guideline. At the same time, blood was collected from each patient and MNL were isolated by gradient centrifuge with Ficoll-400. Total RNA was purified from MNL and semi-quantitative RT-PCR was performed. After reverse transcription, PCR was done with primers for human betaARK1 and GAPDH as external control. betaARK1 levels were expressed by ratio to GAPDH level and estimated the relations with clinical and Echocardiographic parameters. Result: We studied confirmed 19 hypertensive patients(10 men and 9 women, mean age of 50.6 years). Echocardiographically measured indices(mean+/-SD) were as follows; LVMI(137.3+/-30.6g/m2), PWT(0.53+/-0.09) and EF(54.6+/-8.5%). Ratio of betaARK1 levels to GAPDH was from 0.10 to 0.96 (0.62+/-0.25). betaARK1 levels were correlated with LVMI(correlation coefficient: r=.502, p=.029) and RWT(r=.627, p=.004). But Systolic BP(r=0.009, p=.93), diastolic BP(r=.07, p=.85) or EF(r=.045, p=.84) were not related to level of betaARK1.
CONCLUSIONS
The betaARK1 level of circulating MNL was correlated well with the degree of the cardiac hypertrophy estimated by LVMI and RWT. This data suggests that activation of sympatho-adrenal system would exert a major role in developing cardiac hypertrophy and we can expect the decreased responsiveness to catecholamine in the heart of hypertensive patients. betaARK1 in circulating MNL might be used as a predictor or marker for LV hypertrophy in hypertensive patients.