Background: To evaluate whether coronary artery bypass grafting (CABG) in patients with congestive heart failure (CHF) modifies beta-adrenergic receptor dysfunction, we measured lymphocytic beta-adrenergic receptor density and function, and plasma catecholamine levels in patients with congestive ischaemic disease scheduled for CABG.
Methods: Assays were performed on 20 patients with CHF at admission and 6 months following CABG; 20 age-matched healthy subjects served as the control group.
Results: Preoperative lymphocyte beta-adrenergic receptor density was significantly reduced in patients with CHF compared with the control group. Similarly, basal adenylyl cyclase as well isoproterenol- and NaF-stimulated adenylyl cyclase activity was significantly reduced in lymphocytic membranes of patients with CHF compared with controls. Conversely, no difference was found in forskolin-stimulated adenylyl cyclase activity between the two groups of patients. Preoperatively, plasma levels of both noradrenaline and adrenaline were significantly higher in patients with CHF compared with the control group. CABG was associated with clinical and haemodynamic improvement in all patients. Lymphocyte beta-adrenergic receptor density and function were also improved. Basal beta-adrenergic receptor density improved from 39.2 +/- 1.7 to 46 +/- 1.5 fmol/mg protein. Basal adenylyl cyclase activity increased from 33.1 +/- 2.6 40 +/- 2.4 pmol/mg protein per min; a significant increase in activity stimulated by isoproterenol (from 41.5 +/- 3.1 to 61 +/- 3.8 pmol/mg protein per min) and by NaF (from 71.8 +/- 2.7 to 85.3 +/- 3.5 pmol/mg protein per min) was also observed. Although postoperative plasma catecholamine levels tended to decrease, the difference compared with preoperative values was not significant.
Conclusion: The results of our study indicate that CABG in patients with CHF is accompanied by the restoration of an almost normal functional state of the lymphocytic beta-adrenergic receptor system.