Perioperative lymphocyte adenylyl cyclase function in the pediatric cardiac surgical patient

Objective: To examine intraoperative and postoperative lymphocyte adenylyl cyclase activities in children undergoing repair of congenital cardiac defects with hypothermic cardiopulmonary bypass. Design: A prospective study. Setting: Tertiary university pediatric hospital. Patients: Twelve children were enrolled into the study to examine intraoperative lymphocyte adenylyl cyclase activities and 12 children were enrolled to examine postoperative lymphocyte adenylyl cyclase activities. Interventions: None. Measurements and Main Results: Basal (unstimulated), isoproterenol, and prostaglandin E-1 stimulated adenylyl cyclase activities, and plasma norepinephrine and epinephrine concentrations were measured. Intraoperative basal (unstimulated), β-adrenergic receptor-stimulated (in response to isoproterenol), and prostaglandin E₁ (PGE₁)-stimulated lymphocyte adenylyl cyclase activities all increased during cardiopulmonary bypass, then decreased immediately after cardiopulmonary bypass. In the postoperative group, a significant decrease in basal (unstimulated), β-adrenergic receptor- and PGE₁-stimulated adenylyl cyclase activities were observed on postoperative day 1 as compared with precardiopulmonary bypass values. Conclusions: In the pediatric cardiac surgical patient, there was an intraoperative enhancement of lymphocyte adenylyl cyclase activities. This increase in adenylyl cyclase activities was followed by reduced lymphocyte adenylyl cyclase activities, including β-adrenergic receptor desensitization, postoperatively, as we have previously documented in adults.