The injection of rabbit blood into cats causes
hypotension, thrombocytopaenia, leukopaenia, a rise in central venous pressure and right ventricular and pulmonary artery pressures and a fall in circulating levels of
fibrinogen. Death occurred rapidly after injection of the rabbit blood in 50% of control animals and was associated with respiratory distress. Measurement of plasma
thromboxane B2 and 6-oxo
PGF1 alpha levels in surviving controls demonstrated a marked elevation in the former with no significant change in the latter. Pretreatment with either the
thromboxane synthetase inhibitor, 1-(cyclo octyl methyl)
imidazole or
aspirin prevented respiratory distress and death and reduced or prevented the elevations in cardiovascular pressures observed in control animals. Neither compound prevented thrombocytopaenia or leukopaenia but did attenuate the rise of
thromboxane B2 following injection of rabbit blood. In addition, pretreatment with 1-(cyclo octyl methyl)
imidazole resulted in an approximately five-fold increase in circulatory levels of 6-oxo
PGF1 alpha five minutes after inducing the
shock. We conclude that
thromboxane A2 plays an important role in pulmonary (and other organs) dysfunction during the
shock induced by injection of heterologous blood. In addition we have shown that inhibition of
thromboxane synthetase in vivo under conditions where
thromboxane A2 is produced leads to an increase in the synthesis of
prostacyclin.