Cardiac metallothionein overexpression improves cardiac contractile function and attenuates oxidative stress in lipopolysaccharide-treated mice
10.3760/cma.j.issn.0253-3758.2011.08.006
- VernacularTitle:金属硫蛋白对败血症小鼠心功能不全及氧化应激作用的研究
- Author:
Peng ZHAO
1
;
Jie ZHANG
;
Xi CHU
;
Hai-Tao YUAN
;
Lian-Qun CUI
;
Xing-Lei ZHU
Author Information
1. 山东大学附属省立医院
- Keywords:
Ventricular function,left;
Sepsis;
Metallothionein;
Oxidative stress
- From:
Chinese Journal of Cardiology
2011;39(8):711-716
- CountryChina
- Language:Chinese
-
Abstract:
Objective This study was designed to examine the impact of the antioxidant metallothionein (MT) on cardiac contractile, intracellular Ca2+ function and oxidative stress in lipopolysaccharide (LPS)-treated mice. Methods Weight and age matched adult male FVB and cardiacspecific MT-overexpressing transgenic mice were injected intraperitoneally with 4 mg/kg Escherichia Coli LPS dissolved in sterile saline or an equivalent volume of pathogen-free saline ( control groups). Six hours following LPS or saline injection, cardiac geometry and function were evaluated in anesthetized mice using the 2-D guided M-mode echocardiography. Mechanical and intracellular Ca2+ properties were examined in hearts. Cell shortening and relengthening were assessed using the following indices: peak shortening (PS)-indicative of the amplitude a cell can shorten during contraction; maximal velocities of cell shortening and relengthening ( ± dl/dt) -indicative of peak ventricular contractility; time-to-PS (TPS) -indicative of systolic duration; time-to-90% relengthening ( TR90 )-indicative of diastolic duration ( 90% rather 100%relengthening was used to avoid noisy signal at baseline concentration). The 360 nm excitation scan was repeated at the end of the protocol and qualitative changes in intracellular Ca2+ concentration were inferred from the ratio of fura-2 fluorescence intensity (FFI) at two wavelengths (360/380). Fluorescence decay time was measured as an indicator of the intracellular Ca2+ clearing rate. Glutathione/glutathione disulfide ratio and ROS generation were detected as the markers of oxidative stress. Results Heart rate was increased while EF was reduced in LPS-FVB mice and heart rate was reduced and EF increased in MT-LPS transgenic mice [(528 ±72) beats/min vs (557 ±69) beats/min, (66 ± 14)% vs (42 ± 10)%, P ＜0.05].Cardiomyocytes from the LPS treated FVB mice displayed significantly reduced peak shortening (PS) and maximal velocity of shortening/relengthening ( ± dl/dt ) associated with prolonged time-to-90%relengthening (TR90), these effects were attenuated in cardiomyocytes from the MT-LPS mice [PS (5 ±1.1 )% vs (7.2 ± 0. 8)%, dl/dt (160 ± 15) μm/s vs (212 ± 36) μm/s, - dl/dt (175 ± 32) μm/s vs (208 ±29)μm/s, TR90 (0.24 ±0.03)s vs (0.19 ±0.02) s, P ＜0.05].LPS treated mice showedsignificantly reduced peak intracellular Ca2 + and electrically- stimulated rise in intracellular Ca2 + as well as prolonged intracellular Ca2+ decay rate without affecting the basal intracellular Ca2+ levels, again, these effects were significantly attenuated in MT-LPS transgenic mice. Metallothionein overexpression also ablated oxidative stress [reduced ROS generation and increased glutathione/glutathione disulfide ratio, ROS(0. 35 ±0.08)A/μg protein vs (0.24 ±0.03) A/μg protein] . GSH/GSSG 2.1 ±0.2 vs 2.6 ±0.4, P ＜0. 05. Conclusion MT overexpression improved cardiac function and ablated oxidative stress in LPS treated mice.
