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Although it is recognized that ATP plays a part in apoptosis, whether and how its level changes en route to apoptosis as well as how ATP is synthesized has not been fully investigated. We have addressed these questions using cultured cerebellar granule cells. In particular, we measured the content of ATP, ADP, AMP, IMP, inosine, adenosine and L-lactate in cells undergoing apoptosis during the commitment phase (0-8 h) in the absence or presence of oligomycin or/and of citrate, which can inhibit totally the mitochondrial oxidative phosphorylation and largely the substrate-level phosphorylation in glycolysis, respectively. In the absence of inhibitors, apoptosis was accompanied by an increase in ATP and a decrease in ADP with 1:1 stoichiometry, with maximum ATP level found at 3 h apoptosis, but with no change in levels of AMP and its breakdown products and with a relatively low level of L-lactate production. Consistently, there was an increase in the cell energy charge and in the ratio ([ATP][AMP])/[ADP](2). When the oxidative phosphorylation was completely blocked by oligomycin, a decrease of the ATP content was found both in control cells and in cells undergoing apoptosis, but nonetheless cells still died by apoptosis, as shown by checking DNA laddering and by death prevention due to actinomycin D. In this case, ATP was provided by anaerobic glycolysis, as suggested by the large increase of L-lactate production. On the other hand, citrate itself caused a small decrease in ATP level together with a huge decrease in L-lactate production, but it had no effect on cell survival. When ATP level was further decreased due to the presence of both oligomycin and citrate, death occurred via necrosis at 8 h, as shown by the lack of DNA laddering and by death prevention found due to the NMDA receptor antagonist MK801. However, at a longer time, when ATP level was further decreased, cells died neither via apoptosis nor via glutamate-dependent necrosis, in a manner similar to something like to energy catastrophe. Our results shows that cellular ATP content increases in cerebellar granule cell apoptosis, that the role of oxidative phosphorylation is facultative, i.e. ATP can also derive from anaerobic glycolysis, and that the type of cell death depends on the ATP availability.

We report the spectrum of phenylalanine hydroxylase (PAH) gene mutations in patients with phenylketonuria (PKU) residing in Lithuania. A total of 184 independent chromosomes was investigated. R408W mutation was first analysed through restriction enzyme digestion of exon 12. The remaining uncharacterised PKU chromosomes were analysed by scanning the whole coding sequence of PAH gene by multiplex 'broad range' denaturing gradient gel electrophoresis. Mutations were identified by fluorescent automated sequencing or by restriction enzyme digestion analysis if an abnormal DGGE pattern was recognised. 21 different mutations were identified for 175 PKU chromosomes, with a mutation detection rate of 95%. The most common ones were R408W (73.5% chromosomes) and R158Q (7.0% chromosomes) whereas the remaining mutations appeared to be rare (relative frequencies 0.5%-2%). The high mutation detection rate obtained is an evidence of the efficiency of PAH genetic testing achieved in Lithuania. Moreover, the definition of the PKU mutation profile in the Lithuanian population will allow to perform a genotype-phenotype correlation study thus making feasible genotyped-based prediction of the biochemical phenotype in newborns with hyperphenylalaninemia. This may be useful for refining diagnosis and anticipating dietary requirements.