Intracellular and extracellular spaces and the direct quantification of molar intracellular concentrations of phosphorus metabolites in the isolated rat heart using 31P NMR spectroscopy and phosphonate markers

✍ Scribed by Kieran Clarke; Russell E. Anderson; Jean-François Nédélec; David O. Foster; Ariff Ally

• Publisher: John Wiley and Sons
• Year: 1994
• Tongue: English
• Weight: 796 KB
• Volume: 32
• Category: Article
• ISSN: 0740-3194
• DOI: 10.1002/mrm.1910320206

✦ Synopsis

Abstract

To quantify metabolite and cation concentrations using NMR spectroscopy, the volumes of intracellular and extracellular spaces must be known. We describe a simple ^31^P NMR spectroscopic method that employs dimethyl methylphosphonate (DMMP) as a marker of total water space and phenylphosphoriate (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 m__M__, 10.1 m__M__, and 3.4 m__M__, 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 ^31^P NMR spectrum.