A selective thromboxane synthetase inhibitor, OKY-046, fails to improve blood rheology in endotoxin-shocked rabbits.

Effects of a selective thromboxane synthetase inhibitor, (E)-3-[4-(1-imidazolylmethyl)phenyl]-2-propenoic acid hydrochloride monohydrate (OKY-046), were studied hemorheologically in endotoxin shocked-rabbits. The animals were intravenously administrated with 0.1 mg of endotoxin 3 times at intervals of 3 days. At 7 days after the last endotoxin injection, endotoxin (0.2 mg.kg(-1)) was intravenously administrated to induce a shock. OKY-046 (30 mg.kg(-1)) was administrated after hypotension was developed by the endotoxin treatment and, then, it was continuously injected at 0.03 mg.kg(-1).min(-1). Blood pressure remained unchanged and hypotensive was maintained during the treatment with OKY-046. Blood was sampled from the femoral artery 15 (before the administration of OKY-046), 45, and 120 minutes after the final administration of endotoxin. Pa(O)(2) increased, and Pa(CO)(2), arterial pH, and base excess (BE) decreased during the endotoxin shock. The decrease of pH and BE was prevented by the administration of OKY-046. In the endotoxin-shocked animals, hematocrit, whole blood viscosity, erythrocyte deformability, plasma fluidity, and the ratio of hematocrit to whole blood viscosity showed no significant differences between the OKY-046 treated animals and non-treated ones. These data show that a selective thromboxane synthetase inhibitor (OKY-046) does not improve the blood rheology during endotoxin shock, although it seems to prevent the acidosis in some extent.