Measurements ofin vivoenergy metabolism in experimental cerebral ischaemia using31P-NMR for the evaluation of protective effects of perfluorochemicals and glycerol

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Abstract
Effects of perfluorochemical (PFC) and glycerol on energy metabolism in cerebral ischaemia were examined by the sequential measurements of in vivo 31P-NMR spectrum using topical magnetic resonance (TMR). Experimental cerebral ischaemia was induced in forty-five Wistar rats by a four-vessel occlusion method. The 31P-NMR spectrum and the EEG were monitored during preischaemic and ischaemic periods and after circulation was restored for various periods up to 240 min. There were several peaks in the 31P-NMR spectrum of the preischaemic rat brain; β-ATP, α-ATP, γ-ATP, phosphocreatine (PCr), phosphodiesters, inorganic phosphate (Pi) and sugar phosphate. As soon as the ischaemia was induced, PCr and ATP decreaseq and Pi increased. The chemical shift of the increased Pi peak decreased, showing acidosis of the brain tissue. After circulation was restored following the 30 min ischaemia, recovery of the 31 P-NMR spectrum occurred within 30 min in all sixteen untreated rats. Recovery of the 31P-NMR spectrum was induced by recirculation only in half of the six rats in the untreated 60 min ischaemia group. None of the six rats in the untreated group showed recovery of the spectrum after 120 min ischaemia. When 20% Fluosol-DA was administered at a dose of 20 ml/kg before the induction of ischaemia, all eight rats showed recovery of the spectrum after 120 min ischaemia. Moreover, four of six rats treated with both PFC and glycerol showed temporary recovery even after 240 min ischaemia. The results showed that measurements of in vivo 31P-NMR spectrum using TMR are very valuable for examining the energy metabolism of cerebral ischaemia, as well as to evaluate the effect of therapeutic drugs on cerebral ischaemia.

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