Increase in the rat blood leukocyte counts induced by PAF-acether is suppressed by general anesthesia.
Blood leukocyte count alterations induced by PAF-acether in anesthetized and nonanesthetized rats were investigated. Intravenous injection of increasing amounts of PAF-acether (1.5-8 micrograms/kg) in nonanesthetized animals induced dose-dependent hemoconcentration and leukocytosis. The former was apparent within 10 min, peaked from 30 min to 1 h, and diminished thereafter. The leukocytosis was noted within 30 min, was maximal at 1 h, and was over 4 h after injection of PAF-acether (4 micrograms/kg). It was characterized by a marked increase in the blood neutrophil counts under conditions in which the number of lymphocytes, monocytes, and eosinophils remained unchanged. PAF-acether-induced leukocytosis occurred in parallel with a marked decrease in the number of bone marrow nucleated cells, suggesting that the latter phenomenon may determine the former one. Leukocytosis by PAF-acether was inhibited dose-dependently by specific PAF-acether antagonists including BN 52021 (median effective dose ED50 = 4.99 mg/kg), WEB 2086 (ED50 = 4.59 mg/kg), and 48740 RP (ED50 = 9.02 mg/kg). General anesthesia by either pentobarbital, urethane, or ether inhalation, but not by ketamine, also impaired the PAF-acether-induced blood leukocytosis under conditions in which the hemoconcentration was not modified. In addition, pentobarbital-anesthetized rats did not have reduced bone marrow nucleated cell counts after PAF-acether stimulation. These findings are consistent with the assessment that PAF-acether-induced rat leukocytosis is accounted for by a bone marrow neutrophil mobilization process that is clearly suppressed in animals anesthetized by pentobarbital.
Bozza
P T
PT
Depto. de Fisiologia e Farmacodinâmica, Instituto Oswaldo Cruz, Rio de Janeiro, Brazil.
Silva
P M
PM
Castro-Faria-Neto
H C
HC
Martins
M A
MA
Cordeiro
R S
RS
D000768:Anesthesia, General; D000777:Anesthetics / Q000494:pharmacology*; D000818:Animals; D001854:Bone Marrow Cells; D006400:Hematocrit; D007958:Leukocyte Count / Q000187:drug effects*; D007964:Leukocytosis / Q000139:chemically induced; D008297:Male; D010972:Platelet Activating Factor / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar
D000777:Anesthetics; D010972:Platelet Activating Factor