CONDITIONS TO STUDY NITRIC-OXIDE GENERATION BY POLYMORPHONUCLEAR CELLS FROM AN INFLAMMATORY EXUDATE IN RATS

Superoxide and nitric oxide release by leukocytes has been usually per formed after exposure to a particular stimulus. We measured the genera tion of superoxide and nitric oxide by cells isolated from an inflamma tory exudate of rats in either the absence or the presence of a variet y of stimuli, Nonstimulated leukocytes generated superoxide radical (1 .2 nmol . 10(6) cells(-1)) and nitric oxide (3.8 nmol . 10(6) cells(-1 )) after 2 h incubation. When cells were incubated with lipopolysaccha rides, opsonized zymosan or phorbol la-myristate 13-acetate, superoxid e level increased while nitric oxide decreased. Phorbol la-myristate 1 3-acetate (100 ng/ml) induced a decrease of 0.88 nmol . 10(6) cells(-1 ) compared with nonstimulated cells, and incubation with N-iminoethyl- L-ornithine increased superoxide production by 0.81 nmol . 10(6) cells (-1). These results provide clear evidence that cells from an inflamma tory exudate which are already triggered are able to generate a consid erable amount of nitric oxide and in less proportion superoxide, that the measure of nitric oxide must be performed without a further stimul us, and that both molecules react in an equimolar proportions to give peroxynitrite anion. (C) 1996 Academic Press, Inc.