Alterations of the β-adrenergic receptor system after thoracic and abdominal surgery

We studied perioperative regulation of the β-adrenergic receptor (βAR) in lymphocytes obtained from 12 patients undergoing noncardiac thoracic surgery and 12 patients undergoing abdominal surgery. βAR number (B(max)) and dissociation constant (K(D)) were determined from [¹²⁵I]iodopindolol saturation binding curves. Function of the βAR/adenylyl cyclase system was assessed by measuring cyclic adenosine monophosphate (cAMP) production in the unstimulated state and in response to maximal stimulation by isoproterenol (ISO) and prostaglandin E₁ (PGE₁). In thoracic surgery patients, basal and ISO-stimulated cAMP production were significantly decreased postoperatively, by 44% and 45%, respectively, with no change in PGE₁-stimulated cAMP. B(max) decreased from 1369 ± 138 (mean ± SE) sites/cell to 891 ± 82 sites/cell postoperatively, while the K(D) increased from 26.7 ± 5.6 pM to 37.8 ± 5.1 pM. In the abdominal surgery patients, there were no significant alterations in cAMP production, but B(max) decreased, from 1235 ± 146 sites/cell preoperatively to 888 ± 65 sites/cell postoperatively, while the K(D) increased from 18.8 ± 3.6 pM to 58.1 ± 12.5 pM. The βAR and its associated effector system are altered during the perioperative period of abdominal and thoracic surgery.