Hemin induces rat neutrophil migration in vivo.

Hemin (30-300 nmol) was injected into the thoracic cavity of rats as described in “Materials and methods.” The control group received sterile PBS. Animals were killed 4 hours after injection, and total leukocytes in the pleural fluid were determined on Neubauer chambers. Differential counting of neutrophils (black bars) and mononuclear cells (white bars) was carried out on May-Grünwald-Giemsa–stained slides. Results are expressed as millions of cells per cavity. Each bar is the mean ± SD from at least 4 animals. *P < .01.