KINETIC EVALUATION OF NITRIC-OXIDE PRODUCTION IN PLEURAL EXUDATE AFTER INDUCTION OF 2 INFLAMMATORY REACTIONS IN THE RAT

NO generation in the course of two acute, non immune, inflammatory rea ctions (pleurisy induced by rat isologous serum and carrageenan) was a ssessed by means of nitrite measurement in pleural exudate from 0.5 to 24 h. NO release varied time-dependently, similarly for the two infla mmatory reactions. A first, but transient, peak was reached in 30 min while a second peak, more sustained, began at the fourth hour and was maximum at the tenth. Kinetic evolution of NO release was consistent w ith activation, in a first step, of a constitutive NO synthase probabl y from endothelial origin (inhibited by 2-Methyl-2-Thiopseudourea sulf ate but not by dexamethasone) and with activation, in a second wave, o f inducible NOS from endothelial and exudative cells. NO release was p otentiated by administration per os of L-Arginine and seems to be invo lved in the evolution of acute inflammatory reactions and oxygen metab olite production.