β2-adrenergic responsiveness in vivo during abdominal surgery

Abstract

We have studied adrenergic function in vivo during anaesthesia and surgery. Epinephrine 50 ng kg-1 min-1 was given by i.v. infusion over 30 min to 10 healthy adult volunteers and to 10 patients undergoing abdominal operations. The cAMP response to stimulation by epinephrine, which was obtained as the area under the curve (AUC) for plasma cAMP concentration divided by the AUC for plasma concentration of epinephrine, was more pronounced during surgery (mean ratio 3.5) than in the control situation (ratio 1.4; P < 0.02). This resulted in greater hypokalaemic and hyperglycaemic responses (ratios -0.67 and 4.5) than in the control group (ratios -0.33 and 1.6, respectively; P < 0.004). Mean arterial pressure decreased in the control group while it increased in the study group, and serum cortisol concentration was higher in those who underwent surgery (P < 0.02). These results are consistent with an increased adrenergic response during abdominal surgery.