To quantify metabolite and cation concentrations using NMR spectroscopy, the volumes of intracellular and extracellular spaces must be known. We describe a simple 31P NMR spectroscopic method that employs dimethyl methylphosphonate (DMMP) as a marker of total water space and phenylphosphonate (PPA) as a marker of extracellular space to determine intracellular and extracellular space volumes in the isolated, perfused rat heart. In vivo and in vitro radiolabel studies were used to verify this method. The difference between the total and extracellular water spaces, determined as milliliters/heart, gave the intracellular volume and allowed direct calculation of myocardial creatine phosphate, ATP, and inorganic phosphate concentrations, which were 13.4 mM, 10.1 mM, and 3.4 mM, respectively, for the glucose-perfused rat heart. The extracellular volume decreased by 84% in hearts subjected to 28 min total, global ischemia and increased by 15% during reperfusion. The method described allows the determination of intracellular energy metabolite concentrations in perfused rat heart directly from a single, fully relaxed 31P NMR spectrum.

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SynopsisIt has been proposed that schizophrenia is a prostaglandin-deficiency disease and also that it is a disease of prostaglandin excess. New evidence is reviewed which suggests that ‘classic’ schizophrenia is due to a specific deficiency of prostaglandin E1 while certain toxic and vitamindeficiency psychoses may be due to a broader spectrum of prostaglandin deficiency. There is also good evidence that a particular schizophrenic subgroup, which includes catatonic schizophrenia but may not be confined to it, is associated with an excess of prostaglandins. Part of the explanation may be that prostaglandin E1 has a ‘bell-shaped’ dose-response curve with high concentrations having effects similar to those of prostaglandin deficiency.