DIFFERENTIAL ANTAGONISM OF PLATELET-ACTIVATING FACTOR-INDUCED NEUTROPHILIA AND GASTRIC HEMORRHAGE IN THE RAT

Intravenous injection of platelet activating factor (PAF) in rats prod uced hypotension, neutrophilia, gastric congestion, and sloughing of t he gastric epithelium. The congestion was quantified by measuring hemo globin in the gastric mucosa. Other lesions were quantified by scores of gross pathology and histopathology. PAF-induced changes in neutroph il levels were prevented by pretreatment with the PAF-antgonist Ro24-4 736, but not by the PAF-antagonist CV-3988. Both PAF antagonists reduc ed the hypotension, the amount of hemoglobin in the gastric mucosa, an d the PAF-induced gastric pathology. These results suggest that PAF re ceptors involved in PAF-induced neutrophil mobilization respond differ ently from PAF receptors in the gastrointestinal and cardiovascular sy stems.