IMPROVED BETA-ADRENERGIC-RECEPTOR FUNCTION AFTER CORONARY-ARTERY BYPASS-GRAFTING IN PATIENTS WITH CONGESTIVE-HEART-FAILURE

Background: To evaluate whether coronary artery bypass grafting (CABG) in patients with congestive heart failure (CHF) modifies beta-adrener gic receptor dysfunction, we measured lymphocytic beta-adrenergic rece ptor 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 foll owing CABG; 20 age-matched healthy subjects served as the control grou p. Results: Preoperative lymphocyte beta-adrenergic receptor density w as significantly reduced in patients with CHF compared with the contro l 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. Con versely, no difference was found in forskolin-stimulated adenylyl cycl ase activity between the two groups of patients. Preoperatively, plasm a levels of both noradrenaline and adrenaline were significantly highe r in patients with CHF compared with the control group. CABG was assoc iated with clinical and haemodynamic improvement in all patients. Lymp hocyte beta-adrenergic receptor density and function were also improve d. Basal beta-adrenergic receptor density improved from 39.2+/-1.7 to 46+/-1.5 fmol/mg protein. Basal adenylyl cyclase activity increased fr om 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 pmo l/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 o ur study indicate that CABG in patients with CHF is accompanied by the restoration of an almost normal functional state of the lymphocytic b eta-adrenergic receptor system.