Role of subcutaneous tissue endotoxin in the production of prostanoid-induced lung injury: comparison with intravenous endotoxin response.
Local injection of endotoxin into soft tissues of the flank results in hypoxia and pulmonary hypertension. Our purpose was to determine whether this was caused by tissue prostanoid production or production by the lung as is seen with endotoxemia. Twenty-six sheep were prepared with lung and flank tissue lymph fistulae. Thirteen sheep were given 2 micrograms/kg Escherichia coli endotoxin into the flank soft tissue, six of which were pretreated with ibuprofen, 12.5 mg/kg. Thirteen sheep were given intravenous endotoxin, 2 micrograms/kg, with six pretreated with ibuprofen. An early hypertensive phase was noted with both insults characterized by pulmonary hypertension, hypoxia, and increased lung lymph flow (QL). With subcutaneous tissue endotoxin, there was a significant increase in tissue lymph TxB2 and 6-keto-PGF1 alpha when compared to lung lymph and increased values in venous plasma compared to arterial plasma, indicating tissue to be the source. With intravenous endotoxin, lung lymph and aortic plasma levels were significantly higher than tissue lymph and venous plasma, respectively. The hypoxia, hypertension and increased prostanoids were prevented using ibuprofen. An increased lung permeability phase was noted with intravenous endotoxin but not with tissue endotoxin. As expected, this phase was not inhibited with ibuprofen and, therefore, not prostanoid-induced.