Signaling mechanisms of elevated neutrophil O2- generation after burn injury.
A full skin thickness burn injury was produced in anesthetized rats by exposing 25% of total body surface area to 98 degrees C water for 10 s. Sham (exposed to 37 degrees C water) and burn rats were killed 1, 3, 7, or 10 days later. The role of Ca2+ signaling and Ca(2+)-related protein kinase C (PKC) activation in neutrophil O2- generation was ascertained by evaluating the effect of treatment of the rats with the Ca2+ entry blocker, diltiazem. There was an overt enhancement of O2- generation by polymorphonuclear leukocytes from burn rats on days 1, 3, and 7 postburn, with the peak release occurring on day 3 postburn. O2- generation comparable to the sham was noted on day 10 after the burn. O2- releases on days 1, 3, and 7 postburn were accompanied by marked elevation of Cai2+ and PKC responses. Like the O2- release, intracellular Ca2+ concentration ([Ca2+]i) response on day 10 after burn was suppressed to levels found in the sham group. The treatment of burn rats with diltiazem prevented the upregulation of both [Ca2+]i and PKC responses as well as O2- generation in neutrophils in rats on days 1, 3, and 7 after the burn. Because previous studies have shown that increases in [Ca2+]i precede O2- generation and degranulation, our results suggest that neutrophil O2- release enhancement in the early stages after burn injury (e.g., days 1-7 postburn) results from an overactivation of the Cai2+ and PKC signaling pathways. The heightened O2- generation during the early burn injury phase might play a role in tissue damage in one or more of host organs.
Sabeh
F
F
Department of Physiology, Stritch School of Medicine, Loyola University of Chicago, Maywood 60153, USA.
Hockberger
P
P
Sayeed
M M
MM
D000818:Animals; D000838:Anions; D002056:Burns / Q000097:blood*; D002118:Calcium / Q000097:blood; D002121:Calcium Channel Blockers / Q000494:pharmacology; D004110:Diltiazem / Q000494:pharmacology; D004789:Enzyme Activation; D008297:Male; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000378:metabolism*; D011493:Protein Kinase C / Q000097:blood; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D013481:Superoxides / Q000378:metabolism*
D000838:Anions; D002121:Calcium Channel Blockers; D013481:Superoxides; D009240:N-Formylmethionine Leucyl-Phenylalanine; D011493:Protein Kinase C; D004110:Diltiazem; D002118:Calcium