Rho-kinase inhibition reverses impaired Ca 2+ handling and associated left ventricular dysfunction in pressure overload-induced cardiac hypertrophy

摘要

Graphical abstract Display Omitted Highlights ? Upregulation of Rho/ROCK signaling pathway plays a significant role in cardiac hypertrophy. ? ROCK inhibition prevents the development of pathological cardiac hypertrophy and related myocardial dysfunction. ? Contractile abnormalities arising due to impaired Ca 2+ -handling improve following ROCK inhibition. ? ROCK inhibition restores the altered expression/activity of Ca 2+ regulating proteins. Abstract Recent studies have implicated a relationship between RhoA/ROCK activity and defective Ca 2+ homeostasis in hypertrophic hearts. This study investigated molecular mechanism underlying ROCK inhibition-mediated cardioprotection against pressure overload-induced cardiac hypertrophy, with a focus on Ca 2+ homeostasis. Cardiac hypertrophy model was established by performing transverse aortic constriction (TAC) in 8-week-old male rats. Groups were assigned as SHAM, TAC and TAC+Fas (rats undergoing TAC and treated with fasudil). Rats in the TAC+Fas group were administered fasudil (5mg/kg/day), and rats in the SHAM and TAC groups were treated with vehicle for 10 weeks. Electrophysiological recordings were obtained from isolated left ventricular myocytes and expression levels of proteins were determined using western blotting. Rats in the TAC group showed remarkable cardiac hypertrophy, and fasudil treatment significantly reversed this alteration. TAC+Fas myocytes showed significant improvement in reduced contractility and Ca 2+ transients. Moreover, these myocytes showed restoration of slow relaxation rate and Ca 2+ reuptake. Although L-type Ca 2+ currents did not change in TAC group, there was a significant reduction in the triggered Ca 2+ transients which was reversed either by long-term fasudil treatment or incubation of TAC myocytes with fasudil. The hearts of rats in the TAC group showed a significant decrease in ROCK1, ROCK2, RyR2 protein levels and p-PLB S16/T17 /SERCA2 ratio and increase in RhoA expression and MLC phosphorylation. However, fasudil treatment largely reversed TAC-induced alterations in protein expression. Thus, our findings indicate that upregulation of the RhoA/ROCK pathway is significantly associated with cardiac hypertrophy-related Ca 2+ dysregulation and suggest that ROCK inhibition prevents hypertrophic heart failure.