[Effects of captopril on myocardial ultrastructure in diabetic rats]

Diabetic rat models were established with intraperitoneal injection of streptozotocin. The animals were randomly divided into four groups: Group 1, normal control (n = 5); Group 2, diabetic control (n = 4); Group 3, diabetics treated with PZI (n = 5); Group 4, diabetics treated with PZI and captopril (n = 5). Specimens taken from free wall of the left ventricle were observed under electron microscope after 10-week treatment, and the volume density (Vv), numerical density on area (Na), numerical density (Nv) and mean volume (V) of mitochondria were measured with stereological quantitation. The results showed that the myocardial changes in Group 4 were much less severe than those in Group 3 and similar to those in Group 1. There was significant difference in Nv (P < 0.05) but not in Vv, Na and V between Group 4 and Group 1. While the changes of Group 3 were relatively obvious. As comparing Group 3 with Group 1, there were significant differences in all of the four parameters (P < 0.05-0.01). It is implied that the renin-angiotensin system may be involved in the pathogenesis of diabetic cardiomyopathy, since captopril can improve and reverse the cardiomyopathy of diabetic rats.