Abstract
We investigated the role of leukotrienes in endotoxin-induced changes in pulmonary circulation. In six conscious sheep, haemodynamic measurements were obtained for the calculation of pulmonary vascular resistance (PVR), along with measurements of arterial oxygen tension (PaO2), leucocyte count (WBC), thromboxane B2 (TxB2), 6-Keto-PgF1 alpha and PgF2 alpha, before and at predetermined intervals after a 10-min infusion of E. coli endotoxin (0.3 microgram/kg), with and without treatment with the leukotriene receptor antagonist, FPL-57231. Endotoxin caused a biphasic response (i.e., phase I = 0-1 h, phase II = 1.5-4 h), with a mean +/- SE increase in PVR to 415 +/- 112% of baseline during phase I and a lesser increase of 175% (range = 153-199%) of baseline during phase II. Mean +/- SE PaO2 decreased from 86 +/- 4 to 67 +/- 6 mmHg and WBC count decreased from 8.6 +/- 0.6 to 2.8 +/- 0.7 thousand/mm3 during phase I, whereas TxB2 increased from 145 +/- 28 to 3164 +/- 1082 pg/ml, 6-Keto-PgF1 alpha from 129 +/- 14 to 438 +/- 114 pg/ml and PgF2 alpha from 122 +/- 7 to 242 +/- 43 pg/ml. One hour infusion of FPL-57231 (1 mg/kg/min) administered prior to and throughout phase I attenuated the phase I increases in PVR without preventing the increases in TxB2; however, it partly attenuated 6-Keto-PgF1 alpha and enhanced generation of PgF2 alpha during phase I. Discontinuation of FPL-57231 was followed by an exaggerated response of PVR during phase II to an average of 209% of baseline (range = 186-235%).(ABSTRACT TRUNCATED AT 250 WORDS)
