leupeptins and Cardiomyopathies

Cardiac dysfunction caused by the impairment of myocardial contractility has been recognized as an important factor contributing to the high mortality in sepsis. Calpain activation in the heart takes place in response to increased intracellular calcium influx resulting in proteolysis of structural and contractile proteins with subsequent myocardial dysfunction. The purpose of the present study was to test the hypothesis that increased levels of calpain in the septic heart leads to disruption of structural and contractile proteins and that administration of calpain inhibitor-1 (N-acetyl-leucinyl-leucinyl-norleucinal (ALLN)) after sepsis induced by cecal ligation and puncture prevents cardiac protein degradation. We also tested the hypothesis that calpain plays a role in the modulation of protein synthesis/degradation through the activation of proteasome-dependent proteolysis and inhibition of the mTOR pathway. Severe sepsis significantly increased heart calpain-1 levels and promoted ubiquitin and Pa28β over-expression with a reduction in the mTOR levels. In addition, sepsis reduced the expression of structural proteins dystrophin and β-dystroglycan as well as the contractile proteins actin and myosin. ALLN administration prevented sepsis-induced increases in calpain and ubiquitin levels in the heart, which resulted in decreased of structural and contractile proteins degradation and basal mTOR expression levels were re-established. Our results support the concept that increased calpain concentrations may be part of an important mechanism of sepsis-induced cardiac muscle proteolysis.

Topics: Actins; Animals; Calpain; Cardiomyopathies; Disease Models, Animal; Dystrophin; Gene Expression; Leupeptins; Male; Mice; Mice, Inbred C57BL; Microscopy, Fluorescence; Myocardium; Myosins; Proteasome Endopeptidase Complex; Proteolysis; Sepsis; TOR Serine-Threonine Kinases; Ubiquitin

Excessive alcohol consumption and alcoholism cause medical problems with high mortality and morbidity rates. In this study we aimed to decrease the alcohol related tissue damage by inhibiting calpain activation which plays an important role in apoptosis and necrosis, in rats with cardiomyopathy induced by acute alcohol consumption. Male Sprague-Dawley rats were separated into four groups (control, vehicle, alcohol and alcohol + inhibitor) with 10 rats in each. Control group received isocaloric maltose while vehicle group received isocaloric maltose with DMSO, and alcohol group received 8 g/kg absolute ethanol by gavage. Inhibitor group received 20 mg/kg calpain inhibitor 1 intraperitonally prior to alcohol administration. Calpain activities, cathepsin L levels and cytochrome c release rates were significantly increased in alcohol group compared to control group (p < 0.05). Serum CK MB and BNP levels of alcohol group were excessively increased compared to control group (respectively p < 0.001 and p < 0.01). Serum BNP levels of alcohol + inhibitor group were significantly (p < 0.05) decreased compared to alcohol group. In addition to these, histological evaluation of light microscope images and the results of DNA fragmentation and immunohistochemical caspase-3 activity results showed significant improvement of these parameters in alcohol + inhibitor group compared to alcohol group. Results of our biochemical and histological evaluation results revealed that the calpain inhibitor N-acetyl-leu-leu-norleucinal may have an ameliorating effect on acute alcohol consumption related cardiac tissue damage due to its effects on cell death pathways.

Topics: Animals; Binge Drinking; Calpain; Cardiomyopathies; Caspase 3; Cathepsin B; Cathepsin L; Creatine Kinase, MB Form; Cysteine Proteinase Inhibitors; Cytochromes c; Disease Models, Animal; Humans; Immunohistochemistry; Leupeptins; Male; Myocardium; Nerve Tissue Proteins

Excessive activation of calpains has been implicated in the pathophysiology of inflammation, trauma, and ischemia reperfusion injury. Here, we investigated the effects of calpain inhibition on myocardial dysfunction and inflammation induced by endotoxin in rats. Rats were treated i.v. with endotoxin (10 mg/kg) or endotoxin plus calpain inhibitors and were then prepared after 4 h for myocardial contractility assessment, detection of endothelium leukocyte interactions, and plasma TNF-alpha, nitrite/nitrate, and endocan levels. Compared with vehicle-treated rats, hearts from endotoxin-treated rats had reduced systolic performance that was partially prevented by calpain inhibitors, i.e., acetyl-leucyl-leucyl-arginal (leupeptin), carbobenzoxy-valyl-phenylalanial (calpain inhibitor III), and N-acetyl-leucinyl-leucinyl-norleucinal (ALLN). Leupeptin and calpain inhibitor III reduced plasma TNF-alpha levels in endotoxin-treated rats. ALLN reduced plasma TNF-alpha and nitrite/nitrate levels in endotoxin-treated rats. Endotoxin treatment increased mesenteric venule leukocyte rolling (10 +/- 3 leukocytes/min vs. 44 +/- 10 leukocytes/min; P < 0.01) and adhesion (2 +/- 2 leukocytes/min vs. 15 +/- 3 leukocytes/min; P < 0.01), which was reduced by calpain inhibitors. Attenuation of leukocyte endothelium interactions observed in calpain inhibitor-treated rats with sepsis was associated with increases in plasma anti-adhesion molecule endocan. In conclusion, calpain inhibitors improved endotoxin-induced cardiac dysfunction, which may be attributed to the modulation of endothelium leukocyte interactions in the inflamed vasculature.

Topics: Animals; Cardiomyopathies; Endotoxins; Glycoproteins; Heart; In Vitro Techniques; Inflammation; Injections, Intravenous; Leukocyte Rolling; Leupeptins; Male; Myocardial Contraction; Myocardium; Nitrates; Nitrites; Rats; Rats, Sprague-Dawley; Shock, Septic; Tumor Necrosis Factor-alpha