Milrinone Attenuates Heart and Lung Remote Injury after Abdominal Aortic Cross-Clamping

BACKGROUND

Phosphodiesterase enzymes play a pivotal role in the pathogenesis of ischemia/reperfusion (IR). We examined the role of milrinone (MIL), a phosphodiesterase 3 inhibitor, on remote injury of the heart and lung after abdominal aortic cross-clamping.

DESIGN

Experimental study.

METHODS

Twenty-one Wistar rats were divided into 3 groups: (1) control (C, n = 7), underwent laparotomy and exploration of abdominal aorta only; (2) IR (n = 7), normal saline was applied intraperitoneally (i.p) before IR induced by clamping of the abdominal aorta for 1 hr and then allowing reperfusion for 1 hr; and (3) MIL + IR (n = 7), MIL was given (0.5 mg/kg, i.p) before IR. After sacrification, the lungs and hearts were taken out for analyses and the tissue malondialdehyde (MDA) and glutathione (GSH) were studied. All tissues were examined under light microscopy and transmission electron microscopy (TEM). Expressions of caveolin (Cav)-1 in the lung and Cav-1 and Cav-3 in the heart were examined immunohistochemically.

RESULTS

The MIL + IR group had significantly a lower magnitude of oxidative stress than the IR group both in the lung and heart (lung: P = 0.03 for MDA and 0.001 for GSH and heart: P = 0.002 for MDA and 0.000 for GSH). In light microscopy, the MIL + IR group had statistically a lower total injury score than the IR group for both the lung and heart tissue (P = 0.03 and P = 0.04, respectively). In TEM, regression of mitochondrial degeneration and lamellar bodies in type II pneumocytes in the lungs and obvious improvements in disruption at the intercalated discs and mitochondrial degeneration in the hearts in the MIL + IR group were detected compared with the IR group. The expression of both Cav-1 and Cav-3 in the MIL + IR group was improved compared with the IR group (P = 0.03 for both).

CONCLUSIONS

MIL attenuates remote injury of heart and lung in lower body IR by inhibiting oxidative stress. Moreover, Cav-1 and Cav-3 might have a potential role in MIL-induced cardioprotection.

Acetaminophen Mitigates Myocardial Injury Induced by Lower Extremity Ischemia-Reperfusion in Rat Model

OBJECTIVE

The injury-reducing effect of acetaminophen, an effective analgesic and antipyretic on ischemia-reperfusion continues to attract great attention. This study analyzed the protective effect of acetaminophen on myocardial injury induced by ischemia-reperfusion in an experimental animal model from lower extremity ischemia-reperfusion.

METHODS

Twenty-four Sprague-Dawley female rats were randomized into three groups (n=8) as (i) control group (only laparotomy), (ii) aortic ischemia-reperfusion group (60 min of ischemia and 120 min of reperfusion) and (iii) ischemia-reperfusion + acetaminophen group (15 mg/kg/h intravenous acetaminophen infusion starting 15 minutes before the end of the ischemic period and lasting till the end of the reperfusion period). Sternotomy was performed in all groups at the end of the reperfusion period and the heart was removed for histopathological examination. The removed hearts were histopathologically investigated for myocytolysis, polymorphonuclear leukocyte (PMNL) infiltration, myofibrillar edema and focal hemorrhage.

RESULTS

The results of histopathological examination showed that acetaminophen was detected to particularly diminish focal hemorrhage and myofibrillar edema in the ischemia-reperfusion + acetaminophen group (P<0.001, P=0.011), while there were no effects on myocytolysis and PMNL infiltration between the groups (P=1.000, P=0.124).

CONCLUSION

Acetaminophen is considered to have cardioprotective effect in rats, by reducing myocardial injury induced by abdominal aortic ischemia-reperfusion.

The effect of ozone treatment on remote organ myocardial injury in an aortic ischemia-reperfusion model

Background

This study aims to investigate the effect of ozone on myocardial ischemia-reperfusion injury occurring after occlusion - reperfusion of infrarenal abdominal aorta in rats.

Methods

Thirty-two Wistar albino rats (weighing 200-250 g) were randomized into four equal groups. The control (sham) group underwent laparotomy and dissection of the infrarenal abdominal aorta without occlusion. Intraperitoneal ozone was applied for 10 days 1 mg/kg/day in the control+ozone group. Afterwards, control+ozone group underwent laparotomy and dissection of the infrarenal abdominal aorta without occlusion. Aortic ischemia-reperfusion and aortic ischemia-reperfusion+ozone groups underwent dissection of the infrarenal abdominal aorta, followed by achieving ischemia and reperfusion by cross-clamping the infrarenal abdominal aorta for 60 minutes and removing the cross-clamp for 60 minutes, respectively. The tissue levels of malondialdehyde and activity levels of superoxide dismutase, catalase, and myeloperoxidase were measured in the myocardial specimens. The tumor necrosis factor, interleukin-6 and troponin-I levels were measured in the plasma. A histopathological examination of the myocardial specimens was undertaken.

Results

Biochemical analysis showed that aortic ischemia-reperfusion significantly increased (p<0.05 vs. control) while ozone significantly decreased (p<0.05 vs. aortic ischemia-reperfusion) the myocardial tissue levels of superoxide dismutase and catalase and level of plasma troponin-I. Histologically, in the aortic ischemia-reperfusion group, myocardial disorganization, myofiber swelling and myofiber eosinophilia in the myocardial tissue samples were significantly increased compared to the control group (p<0.05 vs. control). However, histopathological changes in the aortic ischemia-reperfusion+ozone group decreased compared to the aortic ischemia-reperfusion group.

Conclusion

The results of this experimental study indicate that ozone attenuates myocardial injury and oxidative stress that develop after infrarenal aortic ischemia-reperfusion through three markers; (i) decreased tissue superoxide dismutase and catalase levels, (ii) d ecreased p lasma t roponin-I l evels, a nd (iii) reduced histopathological changes, albeit not statistically significant.

The effects of sildenafil and n-acetylcysteine on ischemia and reperfusion injury in gastrocnemius muscle and femoral artery endothelium

Purpose

We aimed to examine the effects of sildenafil and n-acetylcystein on ischemia/reperfusion injury in femoral artery endothelium and gastrocnemius muscle.

Basic methods

32 rats of Sprague-Dawley breed were randomly divided into four groups (n = 8). Median laparotomy was performed, then a 120-minute ischemia was created by microvascular clamping of infrarenal aorta, followed by the release of clamping. In sildenafil group, 1 mg/kg of sildenafil infusion and in the n-acetylcystein group, 100 mg/kg of n-acetylcystein infusion was administered after release of clamps. Blood samples and tissue samples of femoral artery and gastrocnemius muscle were extracted for a histopathological evaluation.

Principal findings

Serum levels of malondialdehyde in ischemia/reperfusion group (6.16 ± 0.79) were higher compared to the control group (4.69 ± 0.33), whereas a significant decrease was detected in sildenafil (5.17 ± 0.50) and n-acetylcystein (4.96 ± 0.49) groups. Femoral artery tissue sections of the control group, mean tumor necrosis factor alpha and hypoxy-induced factor-1 alpha immunoreactivity were found to be negative. In the ischemia/reperfusion group, mean tumor necrosis factor α immunoreactivity was intense and mean hypoxy-induced factor-1 alpha immunoreactivity was 51–75%. In the ischemia/reperfusion + Sildenafil and ischemia/reperfusion + NAS groups, mean tumor necrosis factor α immunoreactivity was slight and mean hypoxy-induced factor-1 alpha immunoreactivity was 26–50%.

Conclusions

In conclusion, sildenafil and n-acetylcystein may reduce femoral artery endothelium and gastrocnemius muscle injury following lower extremity ischemia/reperfusion.

Adrenomedullin attenuates aortic cross-clamping-induced myocardial injury in rats

BACKGROUND

In this study we investigate the effects of adrenomedullin on myocardial injury after ischemia-reperfusion (I/R) after abdominal aortic surgery.

METHODS

Thirty-two Wistar rats were randomized into 4 groups (n = 8) as follows: control group (sham laparotomy), the aortic I/R group, aortic I/R plus adrenomedullin group (underwent aortic I/R periods, and received a bolus intravenous injection of .05 μg/kg/min adrenomedullin), and the control plus adrenomedullin group.

RESULTS

Biochemical analysis showed that aortic I/R significantly increased (P < .05) the plasma levels of troponin-I and tumor necrosis factor-α, and the myocardial tissue levels of malondialdehyde, superoxide dismutase, catalase, and angiotensin II, whereas aortic I/R plus adrenomedullin significantly decreased these same factors (P < .05). Aortic I/R significantly increased (P < .05) myocardial tissue levels of nitric oxide whereas aortic I/R plus adrenomedullin significantly increased the same factor (P < .05).

CONCLUSIONS

These results indicate that adrenomedullin has protective effects against myocardial injury induced by abdominal aortic I/R in rats.

The effect of iloprost on renal dysfunction after renal I/R using cystatin C and beta2-microglobulin monitoring

The purpose of this study was to investigate the effect of iloprost, a cytoprotective prostacyclin analog, on renal injury during unilateral renal I/R in rats and to determine whether the levels of serum cystatin C (CyC) and beta2-microglobulin (B2M), as markers of glomerular function, might denote this injury. Thirty-two Wistar rats were randomized into four groups (n = 8) as follows: control (sham laparotomy), renal I/R (60-min left renal ischemia and 120-min reperfusion), renal I/R + iloprost (20 ng kg(-1) min(-1) infusion during renal I/R period, i.v.), and control + iloprost. Blood and kidney tissue samples were obtained for biochemical and histological analysis from all rats. Serum urea, creatinine, CyC, and B2M levels were evaluated for biochemical analysis. Histopathological changes in renal structure were examined for histological analysis. Serum urea, creatinine, and CyC levels were significantly increased in the renal I/R group. Iloprost treatment decreased these three markers in the renal I/R + iloprost group. beta2-Microglobulin levels were not significantly changed in any group. Histological analyses showed that renal I/R elicited significant renal injury, whereas iloprost significantly decreased I/R-induced renal injury. Serum CyC level is one of the good indicators of acute renal damage due to I/R produced by renal artery occlusion. In contrast, we have shown that there are no significant changes in the levels of serum B2M levels that would make it an accurate diagnostic tool for detecting acute changes in renal injury subject to renal I/R in rats.