Ca2(+)-dependent and Ca2(+)-independent proteinase contents in the skeletal muscle in septic rats.
This study assessed sepsis-induced changes in the contents of calpain and cathepsin B in rat soleus muscle. Sepsis was induced in rats by intra-abdominally implanting fecal pellets containing Escherichia coil and Bacteroides fragilis. Intact soleus muscles were isolated from non-operated control rats, and from rats sacrificed 1 and 2 days after they were implanted with bacteria-free (sterile implanted) or bacteria-laden (septic implanted) pellets. Western blot analyses of muscle homogenates were performed to identify and quantitate these proteinases using specific antibodies. No significant differences in cathepsin B contents were observed between the septic and nonseptic animals on days 1 and 2, post-implantation. Among the three distinct bands recognized by anti-calpain, two prominent bands of 80 and 76 kDa, representing calpain subunits, did not seem to be altered in septic rats compared to the nonseptic groups. The content of the 45-kDa subunit decreased in both the septic and sterile groups compared with non-operated control. These results along with our previous observations suggest that although Gram-negative sepsis does not appear to have an effect on Ca2(+)-insensitive lysosomal cathepsin B content or activity, it upregulates the activity of the Ca2(+)-dependent calpain but not its content in the skeletal muscle during sepsis.
Ahmad
S
S
Department of Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, Illinois 60153, USA.
Choudhry
M A
MA
Sayeed
M M
MM
D000818:Animals; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism*; D002154:Calpain / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D002401:Cathepsin B / Q000737:chemistry / Q000378:metabolism*; D004927:Escherichia coli Infections / Q000201:enzymology / Q000378:metabolism / Q000401:mortality; D008297:Male; D018482:Muscle, Skeletal / Q000737:chemistry / Q000201:enzymology* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D018805:Sepsis / Q000201:enzymology* / Q000378:metabolism / Q000401:mortality
D002154:Calpain; D002401:Cathepsin B; D002118:Calcium