ABSTRACT
<p><b>OBJECTIVE</b>To investigate the effect and mechanism of Compound Salvia injection (CSI) on nitrate ester tolerance.</p><p><b>METHODS</b>Eighty-four patients with coronary heart disease (CHD) were randomly divided into three groups, Group A treated with isosorbide dinitrate (ISD, 15 mg, 4 times per day) alone, Group B with ISD plus CSI and Group C with ISD plus vitamin C. The therapeutic course for all groups was 10 days. The tolerance to nitrate ester and blood pressure were monitored. Before and after treatment, the color Doppler ultrasonic apparatus was used to detect the baseline value of humeral arterial internal diameters (D0), the humeral arterial dilatory response under compression [D1, that is, the flow-mediated vasodilation (FMD)] and the vasodilatory response after sucking of nitroglycerin (D2). And the blood levels of endothelin-1 (ET-1), endothelial nitric oxide synthase (eNOS) mRNA expression were determined. The endothelial-dependent vasodilation (EDD) was expressed by (D1 - D0)/D0 x 100%, and the endothelial-independent vasodilation (EID) was expressed by (D2 - D0)/D0 x 100%.</p><p><b>RESULTS</b>(1) The occurrence rate of nitrate tolerance in Group B and C (28.57% and 35.7%) was lower than that in Group A (64.29%), but insignificant difference was found between the former two. (2) After treatment, blood pressure increased in Group A to the level of pre-treatment, that in Group C also increased but still lower than that of pre-treatment, while insignificant increase was observed in Group B, comparison between Group B and C showed significant difference (P < 0.05). (3) After treatment, EID lowered in Group A, EDD increased in Group B and C (P < 0.05), EDD and EID in Group B and C were higher than those in Group A (P < 0.05), and EDD was higher in Group B than in Group C (P < 0.05). (4) After treatment, ET-1 mRNA expression lowered in Group B, eNOS mRNA expression increased in Group B and C, with significant difference as compared with those before treatment and those in Group A (P < 0.05), and eNOS mRNA expression in Group C was lower than that in Group B (P < 0.05).</p><p><b>CONCLUSION</b>CSI could partially prevent the occurrence of tolerance to nitrate ester, with the effect better than vitamin C, the mechanism might be related with its regulation on eNOS, ET-1 mRNA expression and protection on vascular endothelial function.</p>