The Rho kinase inhibitor, fasudil, ameliorates diabetes-induced cardiac dysfunction by improving calcium clearance and actin remodeling.

Previous study showed inhibition of RhoA and Rho kinase (ROCK) activity with fasudil could alleviate diabetes-induced cardiac dysfunction partially due to improvement of myocardial fibrosis. However, the effect of fasudil on intracellular calcium cycling and actin remodeling, both of which are important to regulate excitation-contract coupling, is still not fully elucidated. In this study, a diabetic cardiomyopathy model was induced by a single intraperitoneal injection of streptozotocin (STZ) in male Sprague Dawley rats. Diabetic rats were treated with fasudil or placebo for 8 weeks. We found that long-term administration of fasudil, a specific Rho kinase inhibitor, significantly ameliorated diabetes-induced contractile dysfunction both at cellular and whole organ levels. Fasudil-treated rats displayed improved diastolic intracellular calcium ([Ca²⁺]_i) removal and rescued expression of protein responsible for [Ca²⁺]_i clearance. Furthermore, our study indicated that fasudil treatment normalized the phosphorylation of the pathway in the diabetic heart, which might be the underlying mechanism accounting for the protective effect of fasudil on [Ca²⁺]_i clearance. In addition, compared to the diabetes group, fasudil also normalized the G/F-actin ratio by preventing cofilin phosphorylation and promoted F-actin organization, suggesting a beneficial effect on actin remodeling. These findings indicate the protective effect of fasudil against diabetes-induced cardiac dysfunction via modulation of Ca²⁺ handling and actin remodeling. Overactivation of RhoA/ROCK plays a key role in the development of DCM. Inhibition of ROCK activity with fasudil improved [Ca²⁺]_i removal in diabetic cardiomyocytes. Fasudil normalized the G/F-actin ratio and promoted F-actin organization. ROCK may be an excellent therapeutic target for the treatment of DCM. KEY of RhoA/ROCK plays a key role in the development of DCM. Inhibition of ROCK activity with fasudil improved [Ca²⁺]_i removal in diabetic cardiomyocytes. Fasudil normalized the G/F-actin ratio and promoted F-actin organization. ROCK may be an excellent therapeutic target for the treatment of DCM.

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