Protective Effectof the NHE1 Inhibitor Buthutin Aon Oxidative Stress-Induced Apoptosis in HUVECs

Abstract Objective: Na+/H+-exchanger 1 (NHE1) inhibitors are considered promising drugs for cardiovascular diseases. Buthutin A (Buth A) is a novel NHE1 inhibitor that was reported by our team recently. In this research, we explored the protective effect of Buth A against angiotensin II (AngII)-induced injury invitro and in vivo. Methods: H9c2 cells and human umbilical vein endothelial cells (HUVECs) were divided into eight groups to investigate whether NHE1, cytosolic calcium ([Ca2+]c), conventional protein kinase C (cPKC), and PKCβ are associated with the protective effect of Buth A invitro. Meanwhile, myocardial hypertrophy was induced by AngII in adult male C57BL/6 mice to verify the protective effect of Buth A invivo. Results: Buth A significantly increased cell viability in AngII-treated H9c2 and HUVEC cells, as well as the superoxide dismutase (SOD) activity of AngII-treated H9c2 cells. Moreover, Buth A reduced the lactate dehydrogenase (LDH) and reactive oxygen species (ROS) levels, number of TUNEL-positive cells, and Bax/Bcl-2 protein expression ratio in AngII-treated H9c2 and HUVEC cells. It also significantly decreased the malondialdehyde (MDA) levels, cell size, and mitochondrial membrane potential in H9c2 cells, all of which were attenuated by the NHE1 activator (LiCl). We further found that the calcium chelator (BAPTA-AM), Na+/Ca2+-exchanger (NCX) inhibitor (SN6), cPKC inhibitor (Go6976), and PKCβ inhibitor (LY317615) had no effect on the protective effect of Buth A in HUVECs, including the inhibition of oxidative stress and apoptosis. Further results indicated that Buth A alleviated oxidative stress and apoptosis caused by myocardial hypertrophy via NHE1 inhibition in AngII-induced mice. Conclusions: Buth A reduced oxidative stress-induced apoptosis and exerted protective effects against AngII-induced cardiac injury invivo and invitro via NHE1 inhibition, which might be associated with [Ca2+]c and PKCβ activities.