Hemorrhagic shock followed by
resuscitation (HSR) causes oxidative stress, which results in multiple organ damage. The kidney is one of the target organs of HSR-mediated oxidative tissue injury.
Heme oxygenase (HO)-1, the rate-limiting
enzyme in
heme catabolism, is induced by oxidative stress; it protects against oxidative tissue
injuries. The aim of the present study was to examine the role of renal HO-1 induction after HSR. Rats were subjected to
hemorrhagic shock to achieve a mean arterial pressure of 30 mmHg for 60 min, followed by
resuscitation with the shed blood. HSR resulted in a significant increase in functional HO-1
protein in the tubular epithelial cells of the kidney, whereas HSR resulted in only a slight increase in gene expression of
tumor necrosis factor (
TNF)-alpha and
inducible nitric oxide synthase (iNOS), and in
protein expression of activated
caspase-3 solely in renal cells where HO-1 expression was absent. HSR also resulted in a significant increase in Bcl-2 gene expression. Pretreatment of HSR animals with
tin-mesoporphyrin (0.5 micromol/kg), a specific competitive inhibitor of HO activity, resulted in a significant decrease in HO activity and exacerbated tissue
inflammation and apoptotic cell death as judged by the marked increase in expression of
TNF-alpha and iNOS, and in activated caspase-3-positive cells, and the significant reduction in Bcl-2 expression, respectively. These findings indicate that HO-1 induction is an adaptive response to HSR-induced oxidative stress and is essential for protecting tubular epithelial cells from oxidative damage through its anti-inflammatory and anti-apoptotic properties.