Ischemia-reperfusion injury (IRI)

Introduction 1955, Sewel

tied up coronary of dog ， loose suddenly

ventricular fibrillation 。

Kane

tied up left entricular branch of coronary of rat ECG no obvious change

relieve deligation arrhythmic

1972 Flore kidney IRI

1978 Modry lung IRI1981 Greenberg intestine IRI

Concept: based on ischemia injury of tissue and organs

restoration of blood flow after transient or ischemia

further reversible or irreversible cell damage

ischemia reperfusion injury （ IRI ）。

pH paradox ischemia acidosis , disorder of function and metb

olism on cell severe IRI

pH paradox calcium paradox pre-perfuse rat heart with no calcium perfusion for 2mi

n perfuse calcium perfusion, cell release enzyme myofibril over-constract, electron signals abnormal ， calcium paradox

Oxygen paradox

Hypoxia liquid perfuse organ or culture without oxygen

injury

restore perfusion severe injury

Ⅰ. Cause of ischemia-reperfusion injury and affecting factor

coronary in spasm antispasmotic thrombosis thrombolytic therapy

1. cause coronary by-pass

operation on heart: no-reflow organ transplant

2 ． Affecting factor

small 5-10min: arrhythmia ⑴ ischemic animals 20-30min: ventricular

time tremor

big 20-40min: reversible injury animals 40-60min: irreversible

injury

diversity between small and big animal

Changes of ischemic perfuse: ATP 、 Ca2+ 、

K+

⑵ collateral( 侧枝 ) circulation ： chronic

⑶ O2 consumption rate

[K+ ] , [Mg2+] protection

⑷ electrolytes

[Na+ ] , [Ca2+] damage

(5) condition of T, pressure,pH,Na+,Ca2+ protection

reperfusion T, pressure,Na+,Ca2+ damage

Ⅱ. pathogenesis of ischemia-reperfusion

injury

 

1. The role of free radical

⑴ kinds and concept of free radical

free radical:

normal: O2 +4e+4H+ 2H2O

O2 → O-•2 H2O2 OH • H2O

e- e- + 2H + e- + H + e- + H +

H2O

oxygen free radical:

O-•2 、 OH •

kinds of

(active oxygen: 1O2、 H2O2 OH • )

free radical lipid free radical:

L•、 LO•、 LOO•

others: Cl•、 CH3•、 NO

(2) mechanism of increase of oxygen free radical

  ① formation of oxygen free radical

 

nature oxidation of Hb , Cyt C

O2 O ‾∙2 H2O2 OH∙ H2O

H2O

oxidation of enzyme : xanthine oxidase(XO)

O ‾∙2 xanthine uric acid

O2 O ‾∙2

Mitochondria: O ‾∙2

normal: O2+4e+4H+→H2O+ATP

abnormal :O2+e→ O·-2

+e +2H+→H202+e+H+→

OH· +e+H+→H20

Cyt P450 O insert C—H C—OH O +2 H + H2O

O ‾∙2 H2O2

Produce of OH· SOD O·-

2+ O·-2+2H+ H2O2+O2

O·-2+H2O2 OH· + OH·+O2

Fenton Haber-Weiss ： SOD Fe2+ Fe3+

O·-2 H2O2 OH· + OH-

（ 2 ） lipid free radicalconcept ：

types ： L· , LO· LOO·

（ 3 ） non- lipid free radical: NO· 、 ONOO-

They are balance between produce and clearance

Haber-Weiss reaction(Fenton reaction )

OH ∙ Fe3+ + O‾∙2 Fe2+ + O2

H2O2

Fe3+ + OH- + OH∙

  O ‾∙2 + H2O2 Fe 盐 O2 + OH-+ OH∙

O‾∙2 + OH∙

1O2 + OH-

CI+ + H2O H2O + OCl-

1O2 OCl- + H2O2 1O2 + Cl- + H2O

photosensitive substance 

O2 1O2 effects:WBC

2O‾∙2 + 2H +

SOD H2O2+ O2

H2O2 O2

Other oxidase 2H+

H2O2

application disinfection

② increase of oxygen free

XD Xanthine oxidase (XO) :

Ischemia ATP [Ca2+]i xanthine xanthine

dehydrogenase oxidase

Xanthine oxidase pathway

ATP ADP AMP

Adenine nucleoside Ca2+

Hypoxanthine nucleoside

Hypoxanthine xanthine+O‾∙2 +H2O

O2

Uricacid +O‾∙2 +H2O

Fe 2+

OH∙

XD

xo

XO

ischemia

reperfusion

The effects of leucocyte

reperfusion ： oxygen consumption of infiltrated WBC

↑70-90% O2

NADPH +2O2 2O·-2 +NADP++H+

NADH+O2+2H+ H2O2+NAD+ +H+

NADPH 氧化酶

NADH 氧化酶

Phenomenon of increase in production of oxygen radicals

1.repiratory burst O‾∙2 \ OH∙

(oxygen burst)

2.hypoxia mitochondria repiratory chain O‾∙2

Ca2+

(3) damage action of free radical

①membrane lipid peroxidationcellular membrane permeability lipid peroxidation of membrane [Ca2+] i calcium overloadcalcium overload  

lipid cross-linked calcium overloadcalcium overload  

inhibition of Na+-pump and Ca2+-pump [Na+] i , [Ca2+] i

 membrane lipid phospholipase C PGs , LTs （花）

peroxidation phospholipase D TXA2

damage of mitochondria membrane ATP

 

② inhibition of protein function enzymes ： stop heart beat IR GSH(blood) injur

y of protein channels:

③ destruction of nuclear acid DNA- DNA, DNA-protein :

(1) mechanism of calcium overload

  Ca2+ input

① abnormal exchange of Na+/Ca2+

ATP Na+-pump [Na+] i

 

exchange of Na+(out)/Ca2+ (in) (convert)

hypoxia exchange

acidosis of Na+(in)/H+(out) [Na+] i

normal exchange of Na+(in)/Ca2+(out) ，

ischemia catecholamine α1 – receptor H+ Ca2+

Na+ Ca2+

IP3 and DG PKC Ca2+

Normal:βreceptor 

α1

Ca2+

S R

catecholamine β – receptor [Ca2+] i   L Ca2+- channel    Ca2+

  pre-apply anti-Ca2+ drugs GOOD ② injury of biomembrane damage of cellular membrane normal glycocalyx Ca2+ bridge Cellular membrane

β Cellular membrane

Cellular membrane

No Ca2+ glycocalyx

 

 

reperfusion Ca2+ glycocalyx

 

 

Ca2+ lipid break up

PLA2

Cellular membrane

Cellular membrane

Damage of mitochondria and sarcoplasmic

 

Damage of

mitochondria ATP

Damage of

Sarcopasmic Ca2+- ATPase calcium

overload

(2) Damage mechanism of calcium overload ①phospholipase injury of cell membrane and cell organ  ②output of Ca2+ consumption of ATP ③Ca2+ + phosphate production of ATP

deposition  ④ [Ca2+] i XO free radical   ⑤ [Ca2+] i

3. role of leukocyte In 1984 ， Mullane found that conorary was obstru

cted 60min ， Engler ， Ischemia phospholipase  

LTs  

Congregate of leukocyte Expression of adhesion moleculeRelease inflammatory factorProduction of free radical 

no-reflow

5. Role of neutrophil :

1) Injury of microvessle

microcirculation ： caliber contracte , dialate

permability

2) Injury of cells

Ⅲ. Changes of function and metabolism 1. changes of heart in ischemia-reperfusion injury arrhythmia heart function cardiac output free radical energy calcium overload damage of mitochondria

reperfusion sweep of ADP ， AMP produce ATP myocardial destruction of membrane structural rupture and dissolve of myofibril damage damage of mitochondrion

2. changes of brain in

ischemia-reperfusion injury

ATP Na+-pump cellular edema

Hypoxia of cells cellular acidosis

Excitability transmitter

inhibitive transmitter

cAMP↑ cGMP↓

activate free fatty acid↑ lipid peroxidation↑

Hisconstructure

Edema , necrosis

3. Others

Colone, kidney

Ⅳ. Principles of prevention and treatment

1. restoring normal perfusion of tissue in time

low temperature;

low pressure;

low flow;

low natrium(sodium);

low pH;

low calcium

2. improve the metabolism of the tissues

ATP; cytochrome C;

3. sweep away free radical: VitE: lose e FR FR (lipid)

VitC: clear OH∙ (water)

β-cartenoids: clear 1O2

GSH

（ 2 ） enzyme scavenger ：

2 O‾∙2 +2H+

H2O + O2

H2O2 H2O+ O2

4. relieve of calcium overload Ca2+ ion blok agent

SOD

CAT

5. CoQ

Inhibit L • (lipid free radical)

2L+ CoQ 2LH+ CoQ

protein enzyme inhibitor:

ulinastatin