[Effects of various doses of endotoxin on physiological and hematological parameters in conscious guinea pigs]

We investigated the effects of various doses (0.2 to 2000 micrograms/kg) of endotoxin on physiological and hematological parameters in our guinea pig model. Bronchoalveolar lavage (BAL) and lung tissue sampling were performed 6 hours after endotoxin injection. Lung damage was assessed by measuring wet to dry lung weight ratio (W/D), lung tissue to plasma accumulation of 125I-albumin (AL: albumin leakage) and BAL fluid to plasma accumulation of 125I-albumin (BALL: bronchoalveolar lavage leakage). Changes in peripheral cell counts were estimated at times 0, 1, 2, 4 and 6 hours after endotoxin injection. Pulmonary cell accumulation was determined by counting the number of cells in BAL fluid and tissue samples fixed for light microscopic examination. Increased W/D and AL were observed only in the high dose endotoxin treatment groups (200 and 2000 micrograms/kg), while BALL increased even in the low dose endotoxin treatment groups (2 micrograms/kg). Decreases in peripheral neutrophil counts at one hour were observed in all endotoxin treated groups. Increase in BAL fluid neutrophils was seen in the 20, 200, and 2000 micrograms/kg groups, while neutrophil accumulation assessed by light microscope was observed in all endotoxin treated groups. We conclude that different amounts of endotoxin are required to affect different parameters of lung injury.