Training differentially regulates elastin level and proteolysis in skeletal and heart muscles and aorta in healthy rats

Exercise induces changes in muscle fibers and the extracellular matrix that may depend on elastin content and the activity of proteolytic enzymes. We investigated the influence of endurance training on the gene expression and protein content and/or activity of elastin, elastase, cathepsin K, and plasmin in skeletal and heart muscles and in the aorta. Healthy rats were randomly divided into untrained (n=10) and trained (n=10; 6 weeks of endurance training with increasing load) groups. Gene expression was evaluated via qRT-PCR. Elastin content was measured via enzyme-linked immunosorbent assay and enzyme activity was measured fluorometrically. Elastin content was significantly higher in skeletal (P=0.0014) and heart muscle (P=0.000022) from trained rats versus untrained rats, but not in the aorta. Although mRNA levels in skeletal muscle did not differ between groups, the activities of elastase (P=0.0434), cathepsin K (P=0.0343) and plasmin (P=0.000046) were higher in trained rats. The levels of cathepsin K (P=0.0288) and plasminogen (P=0.0005) mRNA were higher in heart muscle from trained rats, but enzyme activity was not. Enzyme activity in the aorta did not differ between groups. Increased elastin content in muscles may result in better adaption to exercise, as may remodeling of the extracellular matrix in skeletal muscle

The influence of heavy physical effort on proteolytic adaptations in skeletal and heart muscle and aorta in rats

Physical effort can elicit differential adaptive changes in the tissues of trained versus untrained rats. Proteolytic activity in the extracellular matrix could be engaged in such adaptation due to its influence on the elasticity of tissues. The effects were investigated of a single physical effort on the activity of elastase, cathepsin K, and plasmin in the skeletal muscles, heart muscles, and aortas of untrained (UT, n=30) and trained (T, n=30) rats. T rats underwent 6 weeks of endurance training. After the last training session, T and UT rats were divided randomly into 3 subgroups. Ten rats from each group (Tpre, n=10) and (UTpre, n=10) were sacrificed. The other 20 rats from each group performed 60 min. of aerobic exercise and were sacrificed immediately post exercise (T0h, n=10; UT0h, n=10) or 3h later (T3h, n=10; UT3h, n=10). Enzyme activity was measured fluorometrically. Cathepsin K and plasmin activity increased in the soleus muscles of UT0h versus UTpre, plasmin activity increased also in UT3h versus UTpre. Elastase, cathepsin K and plasmin activity increased in the heart muscles of T0h and T3h versus Tpre. No aortic differences were observed. Thus, a single bout of physical effort elicited different responses in tissues of T versus UT rats. Increased proteolytic enzyme levels in muscles could influence tissue remodeling. Unchanged aortic cathepsin K levels may help prevent aortic remodeling and neointima formation

The Blocking on the Cathepsin B and Fibronectin Accumulation in Kidney Glomeruli of Diabetic Rats

Hyperglycemia results in the activation of tissue angiotensin II. Angiotensin II stimulates the synthesis of ECM proteins and causes a decrease activity of proteolytic enzymes. The aim of this study was to assess the impact of multilevel blocking of the RAAS, cathepsin B activity, and fibronectin accumulation in the glomerular in the rats diabetes model. Sixty male Wistar rats were initially included. Diabetes was induced by intravenous administration of streptozotocin. The animals were randomized to six groups of ten rats in group. Rats in the four groups were treated with inhibitors of the RAAS: enalapril (EN), losartan (LOS), enalapril plus losartan (EN + LOS), and spironolactone (SPIR); another group received dihydralazine (DIH) and the diabetic rats (DM) did not receive any drug. After six weeks, we evaluated blood pressure, 24 h urine collection, and blood for biochemical parameters and kidneys. In this study, fluorometric, ELISA, and immunohistochemical methods were used. Administration of EN + LOS increased activity of cathepsin B in homogenates of glomeruli compared to DM. Losartan treatment resulted in reduction of the ratio kidney weight/body weight compared to untreated diabetic rats. SPIR resulted in the increase activity of cathepsin B in the homogenate of glomeruli. The values of cathepsin B in the plasma of rats in all studied groups were similar and showed no tendency

Activity of Proteolytic Enzymes and Level of Cystatin C in the Peripartum Period

Objectives. The aim of the study was to evaluate the activity of cathepsin B, collagenases, trypsin, and plasmin and concentration of cystatin C in serum of healthy pregnant women in peripartum period. Study Design. The study group included 45 women in uncomplicated pregnancies. Blood samples were collected in four time points. Enzyme activity was measured by spectrofluorometric method. The level of cystatin C was measured using immunonephelometric method. Results. Mean activity of cathepsin B and the level of serum cystatin C were significantly higher in the study group. Collagenase activity was significantly lower in the study group than the control group. No differences in collagenase, plasmin, and trypsin activity on each day of the peripartum period were found. Conclusion. High activity of cathepsin B and increased level of cystatin C are typical for women in late pregnancy. Those levels significantly decrease after delivery which can be associated with potential role of those markers in placental separation. The insignificant changes of cystatin C level in the peripartum period seem to exclude the possibility of using cystatin C as a marker for renal insufficiency in the peripartum period but additional research is necessary to investigate the matter further