Effects of Shenmai injection and its bioactive components following ischemia/reperfusion in cardiomyocytes

The aim of the present study was to determine whether the myocardial protective function of Shenmai injection (SM) during ischemia/reperfusion (I/R) is attributable to its regulation of intracellular calcium (Ca²⁺) and phospholamban (PLB) levels. Cultured neonatal Sprague Dawley rat cardiomyocytes were used to compare the effects of normoxia, total saponins of Panax ginseng (TSPG), ginsenoside Rg1 (Rg1) and SM treatments in rat myocardial cells following I/R. For each of these treatment groups, the mRNA and protein levels of PLB and the sarco/endoplasmic reticulum Ca²⁺ ATPase (SERCA) were evaluated, in addition to the cytoplasmic Ca²⁺ concentration [Ca²⁺]_i and the rate of apoptosis. The results indicated that I/R markedly decreased phosphorylated PLB and SERCA expression and that SM was able to mitigate this effect, while TPSG and Rg1 were not. Furthermore, SM appeared to prevent aberrant apoptosis and restore the depleted [Ca²⁺]_i resulting from I/R. The protective efficacy of SM against heart disease following I/R may, therefore, be due in part to its effect on intracellular Ca²⁺ homeostasis. SM may exert its protective effects by relieving PLB inhibition, and the pharmacodynamic actions of SM appear to be significantly more effective than those of its bioreactive components, TPSG and Rgl.