After hypothermic CPB, glucagon levels were lower than in the normothermic group. Similar findings were observed by Kuntschen et al. Lower central temperature or a higher blood glucose level after hypothermic CPB may explain this difference. Moreover, it appears that glucagon is not responsible for the greater hyperglycemia observed after hypothermic CPB.
As reported previously, plasma cortisol concentrations were lower during hypothermic CPB than during normothermic CPB. This result was similar to that of other studies using different anesthetic agents in that plasma cortisol decreased 15 min after starting hypothermic CPB which was most likely because of hemodilution in the face of unchanged secretion. By contrast, cortisol secretion increased during normothermic CPB. After rewarming, cortisol was higher than in the normothermic group in the study of Kuntschen et al but the difference was not significant in the present study.
In previous studies GH increased before and during normothermic and hypothermic CPB.* In group 1, GH decreased significantly after induction of anesthesia and 15 min after starting hypothermic CPB, then slightly increased at 30 min of CPB. A parallel trend was observed in group 2 but the changes were not significant.