Abstract 172

1. Background. The role of NO, a compound involved in neurotransmission and regulation of cerebral blood flow, in cerebral ischaemia is still not fully elucidated yet. Although well studied in adult systems of cerebral ischemia / hypoxia, information on NO in perinatal asphyxia (PA) is limited and, in particular, no direct evidence for its generation was provided. We therefore decided to study NO generation in brain of asphyctic rat pups by biophysical and biochemical methods.

2. Methods. We used a non-sophisticated, well-documented rat model resembling the clinical situation in PA: rat pups delivered by cesarean section were placed into a water bath at 37°C still in patent membranes for various asphyctic periods (upto 20 min). Brain pH, cerebral blood flow(CBF). nNOS mRNA (by northern and dot blot analysis). nNOS immunoreactive protein (by Western blot analysis) and NOS activity were determined; generation of NO was evaluated directly by electron paramagnetic resonance(EPR) spectroscopy.

3. Results. nNOS mRNA, NO activity and NO generation as evaluated by EPR were unaffected, whereas nNOS immunoreactive protein 150 kD was decreasing and 136 kD was increasing with the length of the asphyctic period.

4. Conclusion. This is the first report on direct evidence for the generation of NO in PA and we demonstrate, that NO production remains unaffected even by 20 min of asphyxia, at a time point when CBF was increased fourfold and severe acidosis was present. Our biochemical and biophysical results form the basis for further investigations on NO in PA.