Combined antihypertensive effect of GSY and metoprolol,based on endothelium-dependent vasodilatation function

OBJECTIVE To investigate the synergistic effect on dilating blood vessels and anti-hypertension of GYS combined with metoprolol.METHODS ① Spontaneously hypertensive rats(SHR)were administered orally with the vehicle,GSY,metoprolol or GSY combined with metoprolol for 4weeks.Blood pressure,which included SBP,DBP and MBP was measured by a noninvasive method every week.At the end of4 weeks,blood was drawn from the ophthalmic venous plexus to determine blood fat levels(serum TC,TG,LDL-c,HDL-c),liver function(serum ALT,AST),and kidney function(serum BUN,UA and Cr)by the ACCUTE(TBA-40FR)automatic.② The aortae of normal SD rats were prepared and cleaned from periadventitial fat and surrounding connective tissue and cut transversely into 4-mm width rings.To observe different concentration of GYS,metoprolol or GSY combined with metoprolol causing relaxation of the isolated aortic rings precontracted until a stable plateau by noradrenaline(NA)directly or in the presence of eNOS inhibitor L-NAME and cyclooxygenase inhibitor indomethacin(INDO)respectively.③ The concentrations of plasma GSY was determined by the HPLC after rats administered orally with GSY or GSY combined with metoprolol for single-dose.DAS data processing software calculated the pharmacokinetic parameters of GSY.RESULTS There was a significant synergism between GYS and metoprolol in lowering blood pressure and the concentrations of serum TC and LDL-c of SHR.The relaxant effect of GYS combined with metoprolol on the aortic rings precontracted by NA could be attenuated by L-NAME or INDO.The AUC0-tof GSY significantly increased after in conjunction with metoprolol.CONCLUSION GYS combined with metoprolol increases the concentrations of plasma GSY and synergistically lowers blood pressure based on endothelium-dependent vasodilatation function(EDVF).