Hyperammonemia and chronic hepatic encephalopathy: an in vivo PMRS study of the rat brain.

The brain energy metabolism of rats affected by chronic hepatic encephalopathy due to portacaval shunting was monitored by in vivo 31P-nuclear magnetic resonance spectroscopy before and after ammonium acetate administration. With respect to healthy unoperated and to sham operated controls, portacaval shunting decreased the levels of the nuclear magnetic resonance (NMR) visible brain phosphocreatine and nucleoside phosphates, and the intracellular [free Mg(2+)]. Ammonium acetate induced a further decrease of the levels of the NMR detectable phosphocreatine and nucleoside triphosphates and of the [free Mg(2+)], while the PMR spectra of the brain of non-shunted rats did not show any significant change even after treatment with ammonium acetate.