RESUMO
Objective To investigate the effect of ischemic preconditioning (IPC) on the expression of a disintegrin and metalloprotease with thrombospondin type 1 motifs (ADAMTS-1), and to study whether the application of small interfering (si)RNA specifically targeting ADAMTS-1 would help to recover IPC protection in the aged heart. Methods The 32 young (4 months) and 32 aged(24 months) male Sprague-Dawley (SD) rats were assigned randomly to IPC group (n=20) and sham operated group (n= 12) respectively. Myocardial samples from the ischemic-reperfused region were harvested for detecting the ADAMTS-1 expression. In addition, the 110 aged SD rats were assignedrandomly to ADAMTS-1 siRNA group and control group (n=55, each). The effects of ADAMTS-1siRNA transfcction on the expression of ADAMTS-1 protein, myocardial infarction survival rate,heart function and myocardial infarction size after IPC were observed.Results Twenty-four hours after IPC, the ADAMTS-1 protein expression increased significantly in iscbemic-reperfused region both in young and aged rats (P＜0. 05), and the protein expression was higher in aged rats than in young rats (P＜0.05). In young-IPC group, the absorbency showed ADAMTS-1 protein expression at 0 hrs and 24 hrs after IPC were 0. 05±0.01 and 0.12±0.03 by immunohistochemical staining, and were 0.68±0. 16 and 1. 17±0.21 by Western blots respectively. In aged-IPC group, the absorbency showed ADAMTS-1 protein expression at 0 hrs and 24 hrs after IPC were 0.07±0. 03 and 0.21 ±0.04 by immunohistochemical staining, and were 0. 76±0. 21 and 1. 48±0. 17 by Western blots. In the aged rats, ADAMTS-1 siRNA transfection inhibited ADAMTS-1 protein expression (0. 66±0. 19and 0.78±0.21, by Western blots at 0 hrs and 24 hrs after IPC, P＞0.05), but didn't improve myocardial infarction survival rates [ADAMTS-1 siRNA group and sham operated group: 14.3% (5/35) vs. 17.1 %(6/35), P＞0.05], left ventricular fractional shortening [(14.0±3.2)% vs. (13.0±2.9)%, P＞0.05] and myocardial infarction size[(39.0±4.1)% vs. (38.0±5.3)%, P＞0.05].Conclusions ADAMTS-1 expression induced by IPC increases significantly in aged versus in young rats. ADAMTS-1 knockdown by siRNA inhibits ADAMTS-1 protein expression but cannot recover the age-associated loss of IPC protection.
RESUMO
AIM:To study the effect of adiponectin (APN) on lipid peroxidation in human umbilical vein endothelial cells (HUVECs) induced by hydrogen peroxide (H2O2) in vitro. METHODS:The effect of H2O2 on apoptosis was measured by flow cytometry with Annexin V-FITC labeling. The concentration of malonaldehyde (MDA) in HUVECs was detected by thiobarbituric acid (TBA) method. The activities of superoxide dismutase (SOD) and catalase (CAT) were measured by colorimetric assay. The scavenging rate on superoxide anion radicals in xanthine oxidase system and OH radicals produced by Fenton reaction were also tested. RESULTS:APN significantly inhibited H2O2-induced apoptosis. H2O2 increased MDA production and reduced the activities of SOD and CAT,which were inhibited by APN. APN did not alter the activities of SOD and CAT in normal condition. APN dose-dependently decreased the superoxide anion radicals,with the scavenging rate of 11.9%,21.4%,36.9%,respectively,and scavenged OH radicals. CONCLUSION:APN inhibits apoptosis and protects endothelial cells against lipid peroxidation insult by scavenging the free radicals.
