The influence of glucose-insulin-potassium (GIK) on the GH/IGF-1/IGFBP-1 axis during elective coronary artery bypass surgery.

ABSTRACT

OBJECTIVES: To investigate the influence of glucose-insulin-potassium (GIK) on the growth hormone/insulin-like growth factor-1 axis. DESIGN: Randomized clinical study. SETTING: University hospital. PARTICIPANTS: Twenty patients, without metabolic disorders, admitted for elective aortocoronary bypass surgery. INTERVENTIONS: GIK therapy. Measurements and main results Blood samples were taken repeatedly during the day of surgery. Ejection fraction (EF) was determined by transesophageal echocardiography before and at the end of surgery. Blood samples were taken on the first postoperative day and at discharge (8 am and 8 pm). During coronary artery bypass graft (CABG) surgery, a rapid decrease (44%) in total IGF-1 occurred in both groups. Directly after cessation of extracorporeal circulation, there was a prompt rise in IGFBP-1. The mean peak value in the control group was more than 3 times higher than in the GIK group. GH secretion was stimulated by surgery in both groups and was enhanced by GIK. B-glucose was significantly higher in the control group during surgery. EF ( approximately 55% at baseline) was unchanged in both groups. Postoperatively, there were no differences between the groups (all parameters). At discharge, IGFBP-1 was unchanged, but insulin was elevated compared with preoperative levels. This was seen in both groups, reflecting a hepatic insulin resistance. Conclusions The authors conclude that GIK blunts the rise of IGFBP-1 and thereby increases the bioavailability of IGF-1. GIK also seems to speed up the return of IGF-1 to baseline. Both mechanisms could be of importance to catabolic high-risk patients with low IGF-1. Hence, GIK has favorable effects on the GH/IGF-1 axis during CABG surgery.