A new model of pulmonary microembolism in the mouse

The method of infusion of hardened red blood cells described by Clement et al. (1983) to induce pulmonary hypertension in the minipig has been modified to obtain a model of pulmonary microembolism in the mouse. In this model, the infusion of hardened red blood cells causes the death of about 90% of control animals in 2-5 min, and the efficacy of a given pharmacological treatment can be assessed in terms of the percentage of animals protected from death 15 min after the infusion. Platelets are not apparently involved, since the number of circulating platelets, plasma levels of TxB2, and PF-4 are not modified, and the mortality in thrombocytopenic animals is not different from controls. Furthermore, aspirin and heparin are totally inactive in this model. Preliminary results with some Ca++ channel blockers (nitrendipine and nicardipine) indicate that these compounds may be active. This experimental model offers an easy and relatively inexpensive test for the characterization of compounds to prevent pulmonary microembolism, acting via a platelet-independent mechanism.