Comparison of the Effects of Chlorpropamide and Glibenclamide on Contractions of Rat Thoracic Aorta

Diabetes mellitus is one of the most common endocrine disorders with increasing prevalence. Cardiovascular complications are among the major causes of death in diabetic patients. Type II diabetes mellitus is generally treated by sulfonylureas. There are contraversial reports regarding cardiovacular side effects of these drugs. Evidence exists about differences in side effects between the first and the second generatins of sulfonylureas. In the present study, the vascular effects of chlorpropamide and glibenclamide belong to the first generation of sulfonyloreas were investigated in healthy male rats. Healthy rats were treated by the above mentioned drugs for periods of one and two months and the response of aortic rings to phenylephrine was examinde and compared to control. The results showed that after two months administration of chlorpropamide the smooth muscle function was changed. These changes included a significant decrease in phenylephrine-induced contraction. Since such changes were not observed after one month chloropropamdie administration it may be concluded that these changes are time-dependent. Such changes were not observed after one or two months Glibenclamide administration. Phenylephrine EC50s was not differ in test groups when compared to control. Thus it is suggested that changes in the characteristics of aortic smooth muscle alpha-adrenoceptors may not be involved in the observed responses. With respect to the result of this study we concluded that at least part of the vascular effect of chlorpropamide can be attributed to the changes in post-receptor cellular components which are involved in signal transduction.