Patients are randomly allocated to blinded intravenous infusion of 0.125M L-glutamic acid solution or saline at a rate of 1.65 ml/kg and hour commencing at or up to 20 minutes before the release of aortic cross-clamp. The infusion is continued for two hours after declamping the aorta after which an additional 50 ml is given at a halved infusion rate.