Effect of prostaglandin F2 alpha and prostacyclin on asphyxic anoxia in cats.

The effects of exogenously applied prostaglandin F2 alpha (PGF2 alpha) and prostacyclin (PGI2) on asphyxic anoxia was studied in curarized and artificially ventilated cats. Anoxia was induced by stopping the ventilation and checking the changes in the EcoG. Cortical resistance (CRs) was evaluated as time between stopping the ventilation and the extinction of ECoG. Cortical recovery (CRc) was expressed as time between restitution of ventilation and reappearance of brain activity. Anoxia resistance index (ARI) was defined as the ratio between these two parameters (CRs/CRc). PGF2 alpha was applied by 5 minute i.v. and intracarotid (i.c.) infusion in a dose of 10 micrograms/kg/min, and PGI2 in a dose of 250 ng/kg/min for 15 minutes intracarotidly. The results show that both the i.c. and i.v. infusion with PGF2 alpha led to a significant decrease of CRs and prolongation of CRc resulting in decrease of ARI. The changes are more expressed at i.v. infusion, PGI2 does not improve the ECoG changes evoked by hypoxia. Suggestions for the possible mechanism of PGF2 alpha action and for the failure of PGI2 to protect the brain are made.