Contribution of complement activation to the rise in blood levels of 6-oxo-prostaglandin F1 alpha during endotoxin-induced hypotension in rabbits.
Administration of endotoxin (lipopolysaccharide W E. coli O111 B4, 0.5 mg/kg i.v.) induced about 20% activation of the complement system (measured as CH50 and C3), a biphasic hypotension, thrombocytopenia and a significant rise in blood levels of 6-oxo-PGF1 alpha. Complement depletion (CH50 and C3 less than 3%) with Cobra Venom Factor significantly reduced the initial fall in blood pressure and the rise in 6-oxo-PGF1 alpha, and abolished the second phase of hypotension and the thrombocytopenia, due to subsequent injection of endotoxin. It is concluded that activation of about 20% of the complement system by endotoxin is a prerequisite for the occurrence of thrombocytopenia and secondary hypotension, and that it is involved in the increase in blood levels of 6-oxo-PGF1 alpha. The results of histamine determinations in rabbit blood and plasma indicate that, besides products derived from prostaglandin endoperoxides, other vasoactive substances, possibly released during complement-mediated adherence aggregation of platelets, might contribute to the endotoxin-induced hypotension.
D015121:6-Ketoprostaglandin F1 alpha / Q000097:blood*; D000818:Animals; D003165:Complement System Proteins / Q000502:physiology*; D004731:Endotoxins / Q000494:pharmacology*; D005260:Female; D006632:Histamine / Q000097:blood; D007022:Hypotension / Q000097:blood* / Q000139:chemically induced / Q000276:immunology; D008297:Male; D011817:Rabbits; D013921:Thrombocytopenia / Q000139:chemically induced
D004731:Endotoxins; D015121:6-Ketoprostaglandin F1 alpha; D006632:Histamine; D003165:Complement System Proteins