MECHANISMS UNDERLYING ACTION OF INJECTION, A TRADITIONAL CHINESE MEDICINE IN CARDIAC FUNCTION IMPROVEMENT.

BACKGROUND

As a bioactive composite extracted from American cockroach, injection (XML) is used for the treatment of congestive heart failure (CHF) in China. Clinical data has provided evidence that XML has positive inotropic properties. The objective of this study was to assess the mechanisms involved in the therapeutical effect of XML on CHF.

MATERIALS AND METHODS

The effects of XML on the cardiac function in isolated rat heart were measured. A Ca imaging technology was used in rat cardiomyocytes (H9c2 cells) to reveal the role of XML on Ca channels. Meanwhile, the effects of XML on the activities of Na+/K+ ATPase and sodium/calcium exchanger were measured. In addition, the level of reactive oxygen species and the protein expressions for the superoxide dismutase and hemeoxygenase were determined in the cardiomyocytes.

RESULTS

The results showed that XML increased the electrical impulse-induced [Ca] in H9c2 cells, which was dependant on extracellular Ca and was abolished by ML218-HCl (a T-type Cachannels antagonist) but not nimodipine (a L-type Cachannels antagonist). Ouabain, a Na+/K+-ATPase inhibitor, increased the electrical impulse-induced [Ca], which was significantly inhibited by XML. Moreover, XML markedly inhibited the Na+/K+ ATPase activity in H9c2 cells. In addition, XML notably reduced the production of reactive oxygen species and enhanced the protein expressions of antioxidant enzymes including superoxide dismutase 1, superoxide dismutase 2 and hemeoxygenase 1 in H9c2 cell.

CONCLUSION

Our findings pave the ways to the better understandings of the therapeutic effects of XML on cardiovascular system.