There is limited evidence that inhibition of the activity of the cytosolic
cysteine protease calpain reduces
ischemia/reperfusion injury. The multiple organ injury associated with
hemorrhagic shock is due at least in part to
ischemia (during
hemorrhage) and reperfusion (during
resuscitation) of target organs. Here we investigate the effects of
calpain inhibitor I on the organ injury (kidney, liver, pancreas, lung, intestine) and dysfunction (kidney) associated with
hemorrhagic shock in the anesthetized rat.
Hemorrhage and
resuscitation with shed blood resulted in an increase in
calpain activity (heart), activation of
NF-kappaB (kidney), expression of iNOS and COX-2 (kidney), and the development of multiple organ injury and dysfunction, all of which were attenuated by
calpain inhibitor I (10 mg/kg i.p.), administered 30 min prior to
hemorrhage.
Chymostatin, a
serine protease inhibitor that does not prevent the activation of
NF-kappaB, had no effect on the organ injury/failure caused by
hemorrhagic shock. Pretreatment (for 1 h) of murine macrophages or rat aortic smooth muscle cells (activated with
endotoxin) with
calpain inhibitor I attenuated the binding of activated
NF-kappaB to
DNA and the degradation of
IkappaBalpha,
IkappaBbeta, and IkappaBvarepsilon. Selective inhibition of iNOS activity with L-NIL reduced the
circulatory failure and liver injury, while selective inhibition of COX-2 activity with
SC58635 reduced the renal dysfunction and liver injury caused by
hemorrhagic shock. Thus, we provide evidence that the mechanisms by which
calpain inhibitor I reduces the
circulatory failure as well as the organ injury and dysfunction in
hemorrhagic shock include 1) inhibition of
calpain activity, 2) inhibition of the activation of
NF-kappaB and thus prevention of the expression of NFkappaB-dependent genes, 3) prevention of the expression of iNOS, and 4) prevention of the expression of COX-2. Inhibition of
calpain activity may represent a novel therapeutic approach for the
therapy of
hemorrhagic shock.