Enhancement of zymosan-induced respiratory burst of rat neutrophils by lead in vitro.
The effect of Pb2+ on serum-treated zymosan (STZ)-induced O2 consumption of rat peritoneal neutrophils was studied. Pb2+ was found to mimic effectively the enhancing action of Ca2+ on the O2 consumption depending on the concentration up to about 80 microM. However, at concentrations over 80 microM, Pb2+ inhibited the O2 consumption. The enhancing effect of Pb2+ on the O2 consumption was further examined using the intracellularly Ca2(+)-depleted neutrophils. Pb2+ also enhanced the O2 consumption of the Ca2(+)-depleted cells as effectively as Ca2+. The Pb2(+)-enhanced O2 consumption of the Ca2(+)-depleted cells was inhibited by N-(6-aminohexyl)-5-chloro-1-naphthalene-sulfonamide (W-7) based on its calmodulin antagonistic action. The effect of Pb2+ on the activity of activator-deficient 3',5'-cyclic nucleotide phosphodiesterase (PDE), a calmodulin-dependent enzyme, was examined. Pb2+ activated PDE as effectively as Ca2+ only in the presence of calmodulin. The Pb2(+)-activated PDE activity was also inhibited by W-7 only in the presence of calmodulin. These results indicated that Pb2+ could replace Ca2+ in the activation process(es) of the respiratory burst, suggesting a possible involvement of calmodulin in the enhancing mechanism of the O2 consumption by Pb2+.
Yatsuyanagi
J
J
Muraoka
S
S
Tsutsui
R
R
Ogiso
T
T
D000818:Animals; D004357:Drug Synergism; D066298:In Vitro Techniques; D007854:Lead / Q000494:pharmacology*; D008297:Male; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism*; D010101:Oxygen Consumption / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains; D015054:Zymosan / Q000494:pharmacology*
D007854:Lead; D015054:Zymosan