Abstract:

Objective To investigate the effects of hydroxy safflor yellow A (HSYA) on contractile function of left ventricle of isolated rat heart. Methods Forty-two rats were randomly divided into control group, HSYA (1-100 μmol/L) group, HSYA (30 μmol/L) control group, HSYA (30 μmol/L)＋glibenclamide (Gli) group, HSYA (30 μmol/L)＋tetraethylammonium (Tea) group, HSYA (30 μmol/L)＋4-aminopyridine (4-AP) group and HSYA (30 μmol/L)＋atropine (Art) group, with 6 rats in each group. Langendorff perfused heart preparation was made, and the isolated hearts were perfused with HSYA in a stepwise fashion. The effects on contractile function of left ventricle before and after treatment with different concentrations of HSYA were observed by PowerLab system from a fluid filled latex balloon in the left ventricle. The influence of different types of K⁺ channel blockers on the effects of HSYA was also observed. Results HSYA reduced left ventricular systolic pressure, left ventricular end-diastolic pressure, maximum rate of increase of left ventricular pressure  and heart rate in a dose-dependent manner （P<0.05 or P<0.01）, while had no significant effect on maximum rate of decrease of left ventricular pressure (P>0.05). Gli and Tea blocked the effects of HSYA in a concentration-dependent manner (P<0.05 or P<0.01), but 4-AP and Art did not block the effects of HSYA (P>0.05). Conclusion HSYA could significantly decrease the myocardial contractility and heart rate in a dose-dependent manner, and its action mechanism might be related to the opening of ATP sensitivity K⁺ channel and Ca²⁺ dependent K⁺ channel.

Key words: hydroxy safflor yellow A, isolated hearts, cardiac function, K⁺ channel