Role of divalent metal ions in serum complement activity of the American alligator (Alligator mississippiensis).
Treatment of alligator serum with different concentrations of EDTA resulted in a concentration-dependent inhibition of serum-mediated sheep red blood cell (SRBC) hemolysis. This inhibition of serum-dependent hemolysis was observed for other chelators of divalent metal ions, such as phosphate and citrate. Treatment of alligator serum with 5 mM EDTA completely inhibited SRBC hemolysis, which could be totally restored by the addition of 5 mM Ca(2+) or Mg(2+), but not Cu(2+) or Ba(2+). These data indicate a specific need for Ca(2+) and/or Mg(2+) in the serum-mediated hemolysis of SRBCs. Kinetic analyses revealed that the addition of 30 mM EDTA 1 min after incubation of SRBCs with serum resulted in only 30% inhibition of hemolytic activity. However, addition of EDTA as early as 3 min post-incubation resulted in complete SRBC hemolysis. Pretreatment of serum with EDTA inhibited the hemolytic activity, but the activity could be restored in a time-dependent manner by the addition of Ca(2+)or Mg(2+). These data indicate that, as in human serum, the need for divalent metal ions occurs early in the alligator serum complement cascade.
Merchant
Mark E
ME
Department of Chemistry, McNeese State University, Box 90455, Lake Charles, LA 70609, USA. mmerchant@mail.mcneese.edu
Verret
Brannon
B
Elsey
Ruth M
RM
D000489:Alligators and Crocodiles / Q000097:blood* / Q000276:immunology / Q000378:metabolism*; D000818:Animals; D002413:Cations, Divalent / Q000494:pharmacology*; D003165:Complement System Proteins; D004492:Edetic Acid / Q000378:metabolism; D004912:Erythrocytes / Q000187:drug effects / Q000276:immunology; D006461:Hemolysis / Q000187:drug effects*; D007700:Kinetics; D012756:Sheep
D002413:Cations, Divalent; D003165:Complement System Proteins; D004492:Edetic Acid