Comparative effects of garlic and aspirin on diabetic cardiovascular complications.

By using streptozotocin-induced diabetic rats as a studied model, our previous experimental results have indicated that daily oral feeding of garlic extract (100 mg/kg BW) could increase the cardiovascular functions in streptozotocin (STZ) rats; the abnormality of lipid profile was prevented; and garlic extract could increase fibrinolitic activities with the decrease of platelet aggregation. Moreover, the plasma insulin level was increased concomitantly with the decrease of plasma glucose level. However, due to the high incidence of atherosclerosis in diabetes, the present study has been continued for further investigation of the effect of garlic extract on the coronary vascular ultrastructural changes. In addition, to identify the possible mechanism(s) of garlic's therapeutic effects, the cyclooxygenase inhibitor, aspirin, has been included in this present study. By using transmission electron microscopic studies, 16 weeks of daily oral feeding of garlic extract (100 mg/kg BW) caused as an antiatherosclerotic agent at the coronary arteriolar (15-30 microns) wall in STZ-rats. Interestingly, the thickening of coronary capillary (5-10 microns) basement membrane also was significantly attenuated within the group of STZ-rats treated with garlic extract. However, the possible direct action of garlic through the cyclooxygenase pathway has not been confirmed by the results of aspirin: The daily oral feeding of aspirin (10 mg/kg BW) in 16-week STZ-rats has not showed reduced arteriolar vascular wall abnormalities. The irregular patterns of fiber matrix, arranging the basement membrane at the arteriolar walls, were still recognized in the same manner as in STZ-rats. Interestingly, the thickening of the capillary basement membrane occurred in 16-week STZ-rats seems to be attenuated by the aspirin received. At present, garlic extract may open the new era in the medicinal use of garlic to prevent diabetic cardiovascular complications.

Effects of adrenomedullin on the cardiac performance and coronary flow in an isolated perfused rat heart model.

The effect of adrenomedullin (AM) on the cardiac performance and coronary flow were studied in an isolated perfused rat heart model based on the modified Langendorff method. The heart rate (HR), electrocardiogram (ECG), left ventricular contraction (LVC) (dP/dt), and coronary flow (CF) were measured before and after the application of AM. The effect of AM on the coronary flow was examined in the model with and without endothelial degradation, using different inhibitors such as N(G)-nitro-L-arginine, glibenclamide, and indomethacin. The present results indicated that AM increased HR and CF, but decreased LVC significantly, while it had no effect on ECG. The vasodilatory effect of AM was discussed in views of endothelial-dependence due to nitric oxide and K+ channel activation.