활성산소종으로 손상되는 토끼 복부 대동맥 내피에서 Captopril과 Enalapril의 항산화효과

Abstract

배경: 활성산소종 (reactive oxygen species; ROS)은 다양한 심혈관계질환과 관계가 있는 것으로 알려져 있다. 특히 혈관 내피세포는 활성산소종에 의한 손상에 매우 취약하다. 여러 연구들에서 angiotensin-converting enzyme (ACE) inhibitor 들이 이러한 손상에 대하여 보호 효과가 있는 것으로 나타나고 있다. 하지만 이러한 효과들이 약제의 sulfhydryl group에 의해 이루어지는 지에 대해서는 논란이 있다. 이 연구에서는 흔히 쓰이는 sulfhydryl-containing ACE inhibitor인captopril과non-sulfhydryl-containing ACE inhibitor인enalapril의 항산화효과에 대해서, 토끼 복부 대동맥의 산화질소 매개 혈관 내피 의존성 이완 (nitric oxide-mediated vascular endothelial relaxation)을 통해 알아보았다.

대상 및 방법: 박리된 토끼 복부 대동맥 환상절편을 Krebs-Henseleit 용액이 들어있는 수조에 넣고, 여러 농도 (10-5, 3 × 10-5, 10-4과 3 × 10-4 M) 의captopril 혹은 enalapril을 전처치 한 뒤 용액을 전기분해 (DC 15 mA, 35초)하여 ROS를 발생시켰다. 약물 전처치와 전기분해 전후로 norepinephrine (10-6 M)으로 혈관수축을 유도한 뒤, acetylcholine (3 × 10-8, 10-7, 3 × 10-7과 10-6 M) 을 연속적으로 투여하며 혈관의 이완 정도를 측정하여 혈관 내피의 기능유지 여부를 판단하였다. 항산화 작용과 superoxide anion (O2• -)과hydrogenperoxide (H2O2) 제거효과와의 관련성을 알아보고자 Cu/Zn superoxide dismutase (SOD) 억제제인 diethyldithiocarbamate (DETCA; 0.5 mM)와catalase 억제제인3-amino-1,2,4-triazole (3AT; 50 mM)을 전처치 후 그 반응을 관찰하였다.

결과: Captopril과enalapril은 모두 ROS 노출에도 농도에 비례하여 혈관 내피 의존성 이완을 유지시켰다 (P < 0.0001). DETCA에 의한 SOD 억제는 captopril과enalapril의 항산화효과를 약화시켰지만 (P < 0.0001), 3AT에 의한 catalase억제는 이들 반응에 아무런 영향을 미치지 않았다.

결론: Sulfhydryl group의 유무와 상관없이, captopril과enalapril은 모두 박리된 토끼 복부 대동맥에서 농도에 비례하여 항산화효과를 가진다. 이들 항산화효과의 기전에는 superoxide anion 제거 작용이 일부 관여한다.|Background: Reactive oxygen species (ROS) are known to be related to many cardiovascular diseases. Vascular endothelium is very liable to injury by ROS. Many studies demonstrated that angiotensin-converting enzyme (ACE) inhibitors have beneficial effects against ROS. We investigated the antioxidant effect of captopril and enalapril (sulfhydryl-containing and non-sulfhydryl-containing ACE inhibitors, respectively) in nitric oxide mediated vascular endothelium-dependent relaxations.

Materials and Methods: Isolated rabbit abdominal aorta ring segments were exposed to ROS by electrolysis (DC 15 mA, 35 seconds) of the organ bath medium (Krebs-Henseleit solution) after pretreatment with various concentrations (10-5, 3 × 10-5, 10-4, and 3 × 10-4 M) of captopril and enalapril. Before and after electrolysis, endothelial function was measured by preconstricting the vessels with norepinephrine (10-6 M) followed by the cumulative addition of acetylcholine (3 × 10-8, 10-7, 3 × 10-7, and 10-6 M). The relevance of superoxide anion and hydrogen peroxide scavenging effect of captopril and enalapril was investigated by additional pretreatment with diethyldithiocarbamate (DETCA; 0.5 mM), an inhibitor of Cu/Zn superoxide dismutase (SOD), and 3-amino-1,2,4-triazole (3AT; 50 mM), an inhibitor of catalase.

Results: Both captopril and enalapril preserved vascular endothelium-dependent relaxation after exposure to ROS in a dose-dependent manner (P < 0.0001). Cu/Zn SOD inhibition by DETCA pretreatment attenuated the antioxidant effect (P < 0.0001), but catalase inhibition by 3AT pretreatment did not influence the antioxidant effect of captopril and enalapril.

Conclusions: Both sulfhydryl-containing ACE inhibitor captopril and non-sulfhydryl-containing ACE inhibitor enalapril protect endothelium against free radical injury in a dose-dependent manner in the isolated rabbit abdominal aorta. This protective effect is related to superoxide anion scavenging.; Background: Reactive oxygen species (ROS) are known to be related to many cardiovascular diseases. Vascular endothelium is very liable to injury by ROS. Many studies demonstrated that angiotensin-converting enzyme (ACE) inhibitors have beneficial effects against ROS. We investigated the antioxidant effect of captopril and enalapril (sulfhydryl-containing and non-sulfhydryl-containing ACE inhibitors, respectively) in nitric oxide mediated vascular endothelium-dependent relaxations.

Materials and Methods: Isolated rabbit abdominal aorta ring segments were exposed to ROS by electrolysis (DC 15 mA, 35 seconds) of the organ bath medium (Krebs-Henseleit solution) after pretreatment with various concentrations (10-5, 3 × 10-5, 10-4, and 3 × 10-4 M) of captopril and enalapril. Before and after electrolysis, endothelial function was measured by preconstricting the vessels with norepinephrine (10-6 M) followed by the cumulative addition of acetylcholine (3 × 10-8, 10-7, 3 × 10-7, and 10-6 M). The relevance of superoxide anion and hydrogen peroxide scavenging effect of captopril and enalapril was investigated by additional pretreatment with diethyldithiocarbamate (DETCA