Our previous studies revealed the protection of
stachydrine hydrochloride (STA) against cardiopathological remodeling. One of the underlying mechanisms involves the
calcium/calmodulin-dependent protein kinase Ⅱ (
CaMKII). However, the way STA influences
CaMKII needs to be further investigated. The
nicotinamide adenine dinucleotide phosphate oxidase 2 (NOX2)-coupled
reactive oxygen species (ROS) overproduction putatively induces the oxidative activation of
CaMKII, resulting in the occurrence of pathological cardiac remodeling and dysfunction in experimental models of mice. Thus, in this study, we assessed the role of the NOX2-ROS signal axis in STA cardioprotection. The transverse aortic constriction (TAC)-induced
heart failure model of mice, the
phenylephrine-induced hypertrophic model of neonatal rat primary cardiomyocytes, and the H2O2-induced oxidative stress models of adult mouse primary cardiomyocytes and H9c2 cells were employed. The echocardiography and histological staining were applied to assess the cardiac effect of STA (6 mg/kg/d or 12 mg/kg/d), which was given by gavage. NOX2, ROS, and excitation-contraction (EC) coupling were detected by Western blotting, immunofluorescence, and
calcium transient-contraction synchronous recordings. ROS and ROS-dependent cardiac
fibrosis were alleviated in STA-treated TAC mice, demonstrating improved left ventricular ejection fraction and
hypertrophy. In the
heart failure model of mice and the hypertrophic model of cardiomyocytes, STA depressed
NOX2 protein expression and activation, as shown by inhibited translocation of its phosphorylation,
p67phox and p47phox, from the cytoplasm to the cell membrane. Furthermore, in cardiomyocytes under oxidative stress, STA suppressed NOX2-related cytosolic Ca2+ overload, enhanced cell contractility, and decreased Ca2+-dependent regulatory
protein expression, including CaMKⅡ and
Ryanodine receptor calcium release channels. Cardioprotection of STA against pressure overload-induced pathological cardiac remodeling correlates with the NOX2-coupled ROS signaling cascade.