Twenty-three HT patients without evidence of acute rejection or echocardiographic dysfunction were assessed. Myocardial biopsy samples and peripheral blood lymphocytes were obtained, and α1- and β-adrenoceptor subtype and GRK subtype mRNA was analyzed using reverse transcript–polymerase chain reaction (RT-PCR).
Mean age was 45 ± 15 years, with a median of time since HT of 205 (351) days. In biopsies, the β1/β2-adrenoceptor ratio was 57 % /42 % , and GRK5 was the most commonly expressed, followed by GRK2. In lymphocytes, the β1/β2 ratio was 3 % /96 % , whereas GRK2 mRNA expression was greater than that of other subtypes. There was no correlation between myocardial and lymphocyte parameters. There were no correlations with clinical variables, but lymphocyte β2 and GRK2 were increased with time since HT.
In the transplanted heart, there is no correlation between mRNA expression of adrenoceptors and GRKs in myocardium and peripheral lymphocytes. With time since transplant, mRNA expression of lymphocyte but not myocardial β2-adrenoceptor and GRK2 increases. Therefore, this dissociation between myocardial and lymphocyte mRNA expression limits the potential use of peripheral blood samples for diagnosis of graft dysfunction.