Dlitiazem inhibits the oxidative stress induced by angiotensin II through growth hormone secretagogue receptor type 1a in human umbilicus vein endothelial cells

Diltiazem has been used for post-transplant hypertension, but the mechanism underlying its protective effect of endothelial cells against angiotensin II (Ang II) - induced impairment remains unclear. Human umbilicus vein endothelial cells (HUVECs) were cultured and divided into seven groups: control, Ang II (10-6M), diltiazem (10-6M), [D-Lys3]-GHRP-6(25μM), diltiazem (10-6M)+Ang II (10-6M), losartan (10-6M)+Ang II (10-6M), [D-Lys3]-GHRP-6 (25μM) + Dil(10-6M)+Ang II (10-6M) groups. Nitric oxide (NO) production, intracellular reactive oxygen species (ROS) levels, protein and mRNA expressions of endothelial nitric oxide synthase (eNOS) and p47 phox subunit of NADPH were evaluated. Results indicated that pre- treatment with diltiazem significantly decreased the intracellular ROS levels and increased NO production. Treatment with 10-6M Ang II for 24h induced a significant decrease in the mRNA and protein levels of eNOS, which was significantly increased by the pre-incubated with diltiazem (10-6M). Treatment with 10-6M Ang II for 24h induced a significant increase in the mRNA and protein levels of p47 phox subunit of NADHP oxidase, which was significantly decreased by the pre-incubated with diltiazem. However, all of these protective roles of diltiazem were attenuated by pre-incubation of [D-Lys3]-GHRP-6. The results reveal that diltiazem inhibits the Ang II - induced oxidative stress in HUVECs, which may be partly mediated by GHSR1a.