흰쥐 간장에서 허혈/재관류로 인한 분비 기능 및 약물대사 변동

Abstract

[한글]

허혈은 생체 장기의 기능적 변동과 조직학적 손상을 초래하며, 비가역적 조직 손상이 일어나기 전에 산소를 재공급 하는 것이 손상 장기의 생존에 필수적이다. 그러나 산소를 재공급 할 경우 허혈시 보다 심한 조직 손상이 초래되며 이같은 재관류 손상은 재관류시

반응성이 높은 활성 산소가 생성되기 때문일 것으로 알려져 있다. 이번 연구에서는 간장 허혈/재관류 후 일어나는 간장분비 기능 변동 및 약물대사 효소들의 활성 변동과 지질과산화와의 관련성을 규명하고자, 간장에 허혈/재관류 조작을 한 후 간장의 담즙 분비 변동 및 약물 대사 효소계의 활성 변동를 관찰하고, 활성산소 생성 억제 및 제거 약물의 효과를 관찰하여 다음과 같은 결과를 얻었다.

1. 혈청 aminotransferase 활성은 간장의 허혈/재관류로 현저히 증가하였으며 활성산소 생성 억제 및 제거 약물 투여로 그 증가가 억제되었다.

2. 간장 부종은 허혈/재관류로 증가되었으며 활성 산소 생성 억제 및 제거 약물은 간장 부종을 억제하여 허혈/재관류를 시행하지 않은 sham operation군과 비슷하였다.

3. 간소포체내 지질과산화는 허혈/재관류로 증가되었으며 활성 산소 생성 억제 및 제거 약물투여로 그 증가가 억제되었다.

4. 담즙 분비 기능은 허혈/재관류 시 유의하게 저하되었으며 활성 산소 생성 억제 및 제거 약물 투여로 cholate 분비 감소는 억제되었으나 담즙 분비량은 별 변동이 없었다.

5. 간장 cytochrome P-450 및 NADPH cytochrome P-450 reductase 활성도는 재관류 5시간 후에 감소되었으며 활성 산소 생성 억제 및 제거 약물은 허혈/재관류로 인한 감소를 억제하였다.

6. Aminopyrine N-demetkylase 활성도는 허헐/재관류로 감소되었으며 활성 산소 생성억제 및 제거 약물 투여로 그 감소가 억제되었다. Aniline-p-hydroxylase 활성도는 재관류후 1시간에 증가되었으며 활성 산소 생성 억제 및 제거 약물을 투여하였을 경우 증가가 관찰되지 않았다.

이상의 결과로 보아 간장의 허혈/재관류는 간장 소포체내의 Cytochrome P-450의 활성을 변동시키고 간기능 장애를 초래하며, 이에는 활성 산소에 의한 지질과산화가 관여하고 활성 산소생성 억제 및 제거 약물은 허혈/재관류로 의한 간 손상의 정도를 감소시킴을 알 수 있었다.

[영문]

Ischemia causes tissue necrosis in a wide variety of pathologic conditions. Permanent deprivation of blood flow is lethal to any tissue and the prudent therapy for ischemia unquestionably is reperfusion. While reperfusion is necessary to reverse the progression towards ischemic death, reperfusion is also thought to be accompanied by its own component of injury. Oxygen free radicals, formed during ischemia/reperfusion, have been proposed as one of the main causes of reperfusion injury. Free radical attacks on biological membrane, such as mitochondria and endoplasmic reticulum, and can lead to the oxidative destruction of the polyunsaturated fatty acids ofthe membranes through lipid peroxidation. However, direct association between microsomal lipid peroxidation in vivo after ischemia/reperfusion and chanties in secretory function and drug metabolism on the liver have not been established.

Therefore, present study was performed to evaluate the hepatic secretory function and the hepatic microsomal drug metabolizing enzyme activity after ischemia/reperfusion preparation in rat fiver. Further, the effect of oxygen free radical scavengers was investigated.

The animals were divided into sham operation group and ischemia/reperfusion, group. The ischemial reperfusion group was subdivided into non-treated control and treated (with superoxide dismutase, allopurinol, alpha-tocopherol, deferoxamine)

groups. Hepatic ischemia was produced by clamping the left branches of portal vein and hepatic artery, resulting in complete ischemia to the median and left lobes while the right lobes remained perfused to prevent intestinal congestion.

Reperfusion was permited by declamping after 1 hour. After 1 or 5 hours of reperfusion, bile was collected, blood was obtained from abdominal aorta, and liver microsomes were isolated.

The results are as fellows. Serum aminotransferase was increased 15∼20 times by ischemia/reperfusion. However, this increase was attenuated by free radical scavengers, especially 5 hours of reperfusion. The wet weight-to-dry weight ratio of the liver was significantly increased by ischemia/reperfusion. Alpha-tocopherol pretreatment minimized the increase of ratio. Malondialdehyde level in the liver microsomal fraction was significantly increased after ischemia/reperfusion, but this increase was attenuated by scavenger pretreatment, especially

alpha-tocopherol. Bile flow and cholate output, but not the bilirubin output, was decreased after ischemia/reperfusion. The free radical scavenger pretreatment restored the secretion significantly. Cytochrome P-450 content was significantly decreased after ischemia/reperfusion and ameliorated by free radical scavenger pretreatment. NADPH cytochrome P-450 reductase activity and aminopyrine N-demethylase activity were also decreased and improved by free radical scavengers pretreatment.

These results indicates that ischemia/reperfusion deteriorate the hepatic secretory function as well as hepatic microsomal drug metabolizing enzyme activity, and the oxygen free radical scavengers attenuate the functional changes of the liver induced by ischemia/reperfusion.