Insulin resistance and heart injury in rats with insulin resistance or type 2 diabetes mellitus.
OBJECTIVE
This study sought to observe heart injury in rats with insulin resistance and type 2 diabetes mellitus, and to explore the relation between insulin resistance and diabetic cardiomyopathy in the presence of type 2 diabetes mellitus.


METHODS
Type 2 diabetes mellitus and insulin resistance were studied in animal models using Wistar rats. Glucose infusion rates (index of insulin resistance, insulin resistance), heart weight, the heart weight to body weight ratio, myocardial apoptotic index, cardiac hydroxyproline content, and cardiac tissue collagen type I and collagen type 3 content were measured. Ultramicrostructure of cardiac muscle cells was also observed.


RESULTS
Glucose infusion rates in type 2 diabetes mellitus and insulin resistance rats decreased (P < 0.01). Injury change of the ultramicrostructure of myocardial cells occurred in rats with type 2 diabetes mellitus and insulin resistance. Heart weight, myocardial apoptotic index, cardiac hydroxyproline content, type I and collagen type 3 content increased in rats with type 2 diabetes mellitus, and insulin resistance (P < 0.05) and in rats with insulin resistance were all lower than they were in type 2 diabetes mellitus rats (P < 0.05). In rats with type 2 diabetes mellitus and insulin resistance, associations of glucose infusion rates with heart weight, heart weight to body weight ratio, myocardial apoptotic index, cardiac hydroxyproline content, and cardiac tissue collagen type I and collagen type 3 were all negative; this result was statistically significant (P < 0.05). However, in normal rats, none of these associations was statistically significant.


CONCLUSIONS
In the presence of type 2 diabetes mellitus, there exists insulin resistance and heart injury. Insulin resistance can injure the heart and plays a significant role in pathogenesis of diabetic cardiomyopathy in type 2 diabetes mellitus.
Yang
Zhong-Hua
ZH
Dept. of Geriatrics, West China Hospital of Sichuan University, Chengdu, Sichuan, China. kouwa9992006@yahoo.com.cn
Peng
Xiao-Dong
XD
D000704:Analysis of Variance; D000818:Animals; D017209:Apoptosis; D001786:Blood Glucose / Q000032:analysis; D001835:Body Weight; D003094:Collagen / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000503:physiopathology*; D006909:Hydroxyproline / Q000378:metabolism; D020287:In Situ Nick-End Labeling; D007333:Insulin Resistance; D008297:Male; D009206:Myocardium / Q000473:pathology*; D032383:Myocytes, Cardiac / Q000378:metabolism / Q000648:ultrastructure*; D051381:Rats; D017208:Rats, Wistar
D001786:Blood Glucose; D003094:Collagen; D006909:Hydroxyproline