Alterations of the β-adrenergic receptor system after thoracic and abdominal surgery
Receptors, Adrenergic, beta
We studied perioperative regulation of the beta-adrenergic receptor (beta AR) in lymphocytes obtained from 12 patients undergoing noncardiac thoracic surgery and 12 patients undergoing abdominal surgery. beta AR number (Bmax) and dissociation constant (KD) were determined from [125I]iodopindolol saturation binding curves. Function of the beta AR/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. Bmax decreased from 1369 +/- 138 (mean +/- SE) sites/cell to 891 +/- 82 sites/cell postoperatively, while the KD 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 Bmax decreased, from 1235 +/- 146 sites/cell preoperatively to 888 +/- 65 sites/cell postoperatively, while the KD increased from 18.8 +/- 3.6 pM to 58.1 +/- 12.5 pM. The beta AR and its associated effector system are altered during the perioperative period of abdominal and thoracic surgery.