| Objective:Our previous studies have shown that glycolysis in RBC is depressed entirely in patients undergoing thoracic and upper abdomen operations, while pentose phosphorate pathway(PPP) is activated at the same time .Now We know that aldose reductase can be actived as the third pathway in RBC in hyperglycemia or with diabetes mellitus patients . We still do not know that how aldose redutase changes under surgical stress. Present literatures have shown that hyperglycemia is related to oxidative stress.In the present study, we investigated what has happened aldose reductase activity in patients undergoing thoracic operation, whether the change of glycose metabolism is related to oxidative stress, and what effect of anesthetics and different anesthetic techniques on glucose metabolism and oxidative stress. Methods:48 ASA physical status I and II patients, undergoing elective thoracic surgery were randomly allocated to one of the three groups with 16 cases each. Anesthesia was induced with midazolam O.lmg/kg, propofol Img/kg and vecuronium 0.15mg/kg and maintained with 1.5-2.0MAC desoflurane ( group I ) or isoflurane ( group II ) inhalation, or combined l.OMAC isoflurane inhalation with epidural block ( group III ) . The venous samples were collected for the measurements of PFK, G-6PD and AR activites, the levels of plasma glucose, cortisol andMDA,GSH before anaesthesia, at 90 min after incision, 60 min after surgery and on the 1st, 2nd postoperative days .Results:(l) The levels of plasma glucose were increased significantly at 90min after incision and kept at a high level till the 2nd postoperative day in all three groups(p<0.05) compared with those before anesthesia.(2) The levels of plasma cortisol in all three groups were increased in different exertent during and after operation . In comparison to the preanesthetic value of plasma cortisol, it was increased markedly from 90min after incision to the 1st postoperaive day of operation in group I ,60 min after completion of operation to the 1st postoperative day in group II (p<0.05),but only on the 1st postoperative day in group III (p<0.05) (3) Plasma MDA was increased significantly on the 1st postoperative day in group I and II (p<0.05), but not in group III, the change of MDA in group III was less than that in group I and II (p<0.05) at the same time .(4)Plasma GSH was decreased markedly on the 1st postoperative day in group I and II (p<0.05), and was not significantly changed in group III.(5) The activity of PFK decreased significantly on the 1st postoperative day in group I and II (p<0.05) ,but not in group III, at that time, the change of PFK in group III was less than that in group I (p<0.05) (6) Erythrocyte G-6PD activites increased significantly on the 1st postoperative day in group I and II (p<0.05) which were not at all time points after anesthesia in group III. (7) The activity of AR increased markedly on the 1st postoperative day in group I and II (p<0.05),while there was no marked increase of that in group III .Conclusions: (1) In the patients undergoing thoracic surgery, the polyol pathway activates while blood glucose and cortisol increase, besides that the glycolysis in RBC is depressed and the pentose phosphorate pathway activates, MDA increases and GSH decreases at the same time. On the 2nd postoperative day all parameters nearly return to the baseline. Thosesuggest that oxidative stress occurrs and the change of glucose metabolism in RBC is one of the oxidative stress responses to surgery. (2) On the 1st postoperative day the changes of cortisol, MDA, PFK in group III were less than those in group I and II, the changes of GSH, G-6PD, AR were lessen,suggest suitable anesthetic techaniques can control the effect of glucose metabolism on oxidative stress, while desflurane or isoflurane can not. |
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