Effect of exogenous insulin on endoplasmic reticulum stress in myocardial tissues during insulin resistance in rabbits undergoing cardiopulmonary bypass / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the effect of exogenous insulin on endoplasmic reticulum stress in myocardial tissues during insulin resistance in the rabbits undergoing cardiopulmonary bypass (CPB).Methods Forty healthy adult New Zealand white rabbits of both sexes,weighing 2.5-3.0 kg,were divided into 4 groups (n =10 each) using a random number table method:control group (group C),CPB group,CPB plus insulin group (group Ⅰ) and CPB plus normal saline group (group NS).Group C received no treatment.An insulin resistance model was established in group CPB.Insulin was continuously infused (the infusion rate was adjusted according to the blood glucose) starting from establishing CPB to 1 day after operation in group Ⅰ.The equal volume of normal saline was given starting from establishing CPB to 1 day after operation in group NS.Blood samples were collected from the left femoral artery,and myocardial tissues obtained before CPB (T1) and at 15,30 and 60 min after aortic opening (T2-4).The level of blood glucose was determined using oxidase method,the level of glucagon was detected by the radioimmunoassay method,and the insulin resistance index was calculated.The expression of inositol-requiring protein-1α(IRE1α),XBP1 and caspase-12 was measured by Western blot.The expression of IRE1α,XBP1 and caspase-12 mRNA was measured by fluorescent quantitative real-time polymerase chain reaction.Cell apoptosis was detected by TUNEL.Results Compared with group C,blood glucose and glucagon levels at T2-4 and insulin resistance index at T4 were significantly increased,and the expression of inositol-requiring protein-1α (IRE1α),XBP1 and caspase-12 protein and mRNA was up-regulated at T4 in CPB,I and NS groups (P＜0.05).Compared with group CPB,blood glucose and glucagon levels at T2-4 and insulin resistance index at T4 were significantly decreased,and the expression of IRE1α,XBP1 and caspase-12 protein and mRNA was down-regulated at T4 in group Ⅰ (P＜0.05).Conclusion Exogenous insulin significantly improves insulin resistance in myocardial tissues,and the mechanism is related to inhibiting endoplasmic reticulum stress and reducing cell apoptosis in the rabbits undergoing CPB.