Effect of Cesarean Delivery on Perioperative Regulation of the β-Adrenergic Receptor System of Human Lymphocytes

We studied the perioperative regulation of the β-adrenergic receptor (βAR) system in lymphocytes obtained before and after surgery from 12 patients undergoing cesarean delivery with spinal anesthesia. Receptor number (B_max) and binding affinity (K_D) were determined by Scatchard analysis of [¹²⁵I]iodopindolol saturation binding curves. Receptor function was assessed by measuring cyclic adenosine 3′,5′-monophosphate (cAMP) production in the unstimulated state and in response to stimulation by isoproterenol, forskolin, and prostaglandin E₁. Basal cAMP production increased 48% postoperatively (P < 0.05), while stimulated cAMP production and B_max and K_D were not significantly changed after surgery. The response to surgery of the βAR system of these patients differed from that of patients undergoing cardiothoracic and abdominal surgery in whom we previously found postoperative down-regulation and desensitization of the βAR system. It is possible that this difference in response is due to amelioration of the stress response to surgery by regional anesthesia, and/or alterations in βAR status by pregnancy. We conclude that pregnancy and regional anesthesia, but not changes in lymphocyte subset distribution, contributed to the lack of effect of surgery on the βAR system in the patients studied.