Role of a disintegrin and metalloprotease with thrombospondin type 1 motifs in aged rat myocardium after ischemic preconditioning / 中华老年医学杂志

ABSTRACT

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.