Liguzinediol exerts positive inotropic effect by enhancing Ca 2+release from sarcoplasmic reticulum mediated by sarcoplasmic reticulum Ca2+ATPase / 中国药理学与毒理学杂志

ABSTRACT

OBJECTIVE To explore kinetic features and its underlying mechanism of the positive inotropic effect of liguzinediol(LZDO)in rats. METHODS ①An In vivo study was made to record the effect of LZDO 20 mg · kg-1 injected for 30 consecutive min from the left external jugular vein on pressure-volume relationships. ②Ex vivo study was used to record the antagonistic effect of LZDO on reduced contractility induced by caffeine. Caffeine and LZDO were perfused as follows:normal perfusion solution, caffeine 0.5 mmol · L-1,and then caffeine 0.5 mmol · L-1+LZDO 100 μmol · L-1. ③ Ca2+ transient from cardiomyocyte sarcoplasmic reticulum (SR) was measured to analyze the effect of LZDO on Ca2 +release blocked by thapsigargin. Thapsigargin and LZDO were perfused as follows:normal perfusion solution,thapsigargin 2 μmol · L-1,and then thapsigargin 2 μmol · L-1+LZDO 100 μmol · L-1.④The SR vesicles were prepared and the effect of LZDO(1,10 and 100μmol·L-1)on sarcoplasmic reticulum Ca2+ATPase(SERCA2a)activity was determined according to the ultramicro-Ca2+-ATP enzyme kit. RESULTS ① LZDO 20 mg · kg- 1 significantly reduced the end-systolic volume (Ves) and enhanced the end-systolic pressure (Pes),stroke volume (SV),ejection fraction (EF),cardiac output(CO),peak rate of rise of left ventricular pressure(+dp/dtmax)and stroke work(SW)(P<0.05). However,LZDO 20 mg · kg-1 did not significantly change the heart rate(HR )or the end-diastolic volume (Ved). ② Caffeine 0.5 mmol · L- 1 significantly enhanced HR,left ventricular developed pressure (LVDP ),and+dp∶dtmax at 5 min after caffeine and decreased at 30 min. However,LZDO 100μmol·L-1 restored the reduced HR,LVDP,and+dp/dtmax induced by caffeine at 30 min(P<0.05).③Thapsigargin 2μmol·L-1 significantly reduced the SR Ca2+transient from perfusion solution group(100±5)%to(51± 5)%(P<0.05) and LZDO 100 μmol · L-1 failed to restore the decreased Ca2+ transient〔(49 ± 4)%〕. Normalized Ca2+transients were reduced by thapsigargin 2μmol·L-1 and thapsigargin 2μmol·L-1+LZDO 100 μmol · L-1. ④ LZDO(10 and 100 μmol · L-1)significantly increased the activities of SERCA2a in perfusion solution group 0.98±0.10 to 1.17±0.20 and (1.43±0.09)μmol Pi·g-1·h-1,respectively(P<0.05). CONCLUSION LZDO can enhance SR Ca2+ gradient by activating the SERCA2a and might be developed to serve as a potential positive inotropic agent in clinical settings.