Prevention of mortality induced by perinatal asphyxia: Hypothermia or glutamate antagonism?

Perinatal asphyxia was induced by keeping pups-containing uterus horns, removed by hysterectomy, in a 37°C or a 30°C water bath. Asphyxia for a period of 21-22 min at 37°C led to a 97% mortality within the first 20 min period following delivery. When the asphyctic period was extended to more than 22 min all the pups died following delivery. When the asphyxia was induced at 30°C, 100% of the delivered pups survived and were accepted by surrogate mothers. The protective effect of hypothermia could be observed even when the pups-containing uterus horns were exposed to a 45-46 min asphyctic period. Pretreatment with dizocilpine (0.2 mg/kg s.c.), or 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(f)quinoxaline (NBQX) (3-30 mg/kg s.c.), administered to the mothers one hour before hysterectomy, reduced slightly the mortality induced by a 21-22 min asphyctic period at 37°C. An increase in survival following a 22-23 min asphyctic period could only be observed after the highest dose of NBQX.