Chronic beta-adrenergic receptor stimulation enhances the expression of G-Protein coupled receptor kinases, GRK2 and GRK5, in both the heart and peripheral lymphocytes.
BACKGROUND
Enhanced expression of G protein-coupled receptor kinase (GRK) has been reported in failing hearts and in the present study the stability of enhanced GRK mRNA expression, and the correlation between the expression level of GRK mRNA in peripheral lymphocytes and in the heart were both evaluated.


RESULTS
Isoproterenol was injected into rats for 2 weeks, and then GRK5 mRNA was assessed by quantitative reverse transcriptase-palymerase chain reaction. An enhanced expression of cardiac GRK5 mRNA was observed even after 4 weeks of recovery. The isoproterenol-induced increased expression of GRK2 and GRK5 mRNA was equally observed in the heart and lymphocytes, and there was a close correlation between the heart and lymphocytes in the level of expression of each GRK mRNA.


CONCLUSIONS
The GRK mRNA level is maintained at a high level for a long period without continuous beta-adrenergic receptor stimulation. The level in circulating lymphocytes could be used as a surrogate marker to estimate the level of cardiac GRK expression and, presumably, the beta-adrenergic receptor function of cardiomyocytes.
Oyama
Naotsugu
N
Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
Urasawa
Kazushi
K
Kaneta
Satoshi
S
Sakai
Hidetsugu
H
Saito
Takahiko
T
Takagi
Chika
C
Yoshida
Ichiro
I
Kitabatake
Akira
A
Tsutsui
Hiroyuki
H
D000318:Adrenergic beta-Agonists / Q000008:administration & dosage*; D000818:Animals; D017868:Cyclic AMP-Dependent Protein Kinases / Q000096:biosynthesis* / Q000235:genetics; D054774:G-Protein-Coupled Receptor Kinase 5; D005786:Gene Expression Regulation / Q000187:drug effects*; D007545:Isoproterenol / Q000008:administration & dosage*; D008214:Lymphocytes / Q000378:metabolism*; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D011943:Receptors, Adrenergic, beta / Q000378:metabolism; D051552:beta-Adrenergic Receptor Kinases
D000318:Adrenergic beta-Agonists; D012333:RNA, Messenger; D011943:Receptors, Adrenergic, beta; D017346:Protein Serine-Threonine Kinases; D017868:Cyclic AMP-Dependent Protein Kinases; D051552:beta-Adrenergic Receptor Kinases; D054774:G-Protein-Coupled Receptor Kinase 5; C517897:Grk5 protein, rat; D007545:Isoproterenol