Effects Of Hesperetin On Blood Pressure And Cardiac Function In Rats

Objectives:1.To observe the effects of hesperetin?HSP?on heart rate and blood pressure in normal rats.2.To investigate the effects of HSP on coronary artery flow and cardiac function in isolated rat hearts by Langendorff isolated heart perfusion system.3.To explore the mechanism of the effects of HSP on the cardiac function of isolated rat hearts by potassium channel blockers.Methods:1.The effects of different doses of HSP?0.3 mg/kg,1 mg/kg,3 mg/kg?on heart rate?HR?,systolic pressure?SP?,diastolic pressure?DP?,mean arterial pressure?MAP?and rate pressure product?RPP?in normal rats were observed by using a single femoral intravenous administration.2.The effects of different concentrations of HSP(10^-5 moL/L,3×10^-5 mo L/L,10^-4 mo L/L)on coronary flow?CF?and cardiac function indexes including heart rate?HR?,left ventricular developed pressure?LVDP?,left ventricular end-diastolic pressure?LVEDP?,positive dp/dtmax?+dp/dtmax?and negative dp/dtmax?-dp/dtmax?in isolated rat hearts were recorded by using of the Langendorff isolated heart perfusion system.3.The mechanism of effects of HSP on cardiac function in isolated rat hearts was explored by applying the calcium-activated potassium channel(K_Ca)blocker tetraethylamonium?TEA?,ATP-sensitive potassium channel(K_ATP)blocker glibenclamide?Gli?,inward rectifier potassium channel(K_IR)blocker barium chloride?BaCl₂?and voltage-activated potassium channel?K_V?blocker 4-aminopyridine?4-AP?,respectively.Results:1.Compared with before administration,HSP?0.3 mg/kg,1 mg/kg,3 mg/kg?could decrease SP,MAP and RPP of normal rats in a dose-dependent manner?P<0.05?,but there were no significant effect on HR and DP of normal rats?P>0.05?.2.Compared with before administration,HSP(10^-5 moL/L,3×10^-5 mo L/L,10^-4 mo L/L)could increase the CF and decrease the LVDP,+dp/dtmax of isolated rat hearts in a concentration-dependent manner?P<0.05?,but there were no significant effect on HR,LVEDP and-dp/dtmax of isolated rat hearts?P>0.05?.3.Compared with HSP 3×10^-5 mo L/L group,the effect of HSP on CF,LVDP and +dp/dtmax could be partially inhibited by 4-AP?P<0.05?,but TEA,Gli and BaCl₂ had no obvious effect?P>0.05?.Conclusion:1.HSP reduces the SP,MAP and myocardial oxygen consumption in normal rats.2.HSP increases the CF and inhibits myocardial systolic function in isolated rat hearts.3.The effects of HSP on isolated rat hearts may be related to the activation of K_V channels on cardiomyocytes,but independent on K_Ca channels,K_ATP channels and K_IR channels.