Modeling in vivo recovery of intracellular pH in muscle to provide a novel index of proton handling: Application to the diagnosis of mitochondrial myopathy
✍ Scribed by J.T. Chen; T. Taivassalo; Z. Argov; D.L. Arnold
- Publisher
- John Wiley and Sons
- Year
- 2001
- Tongue
- English
- Weight
- 232 KB
- Volume
- 46
- Category
- Article
- ISSN
- 0740-3194
- DOI
- 10.1002/mrm.1271
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✦ Synopsis
Abstract
Post‐exercise recovery of intracellular pH (pH~i~) assessed using phosphorus magnetic resonance spectroscopy has not been previously evaluated in its entirety due to its complex time‐course and missing data points resulting from a transient loss of inorganic phosphate signal. By considering the transition from exercise to recovery as a step function input, pH~i~ recovery was modeled based on the creatine‐kinase equilibrium, and the entire pH~i~ recovery was characterized by calculating the time required for pH~i~ recovery (t~pHrec~). Applying this methodology, normal subjects showed a strong linear correlation between phosphocreatine (PCr) half‐time and t~pHrec~ (r = 0.90, P < 0.001). In mitochondrial myopathy (MM) patients with weakness in the limb examined, 9/10 had faster pH~i~ recovery relative to PCr recovery; wide normal ranges from a control group which included deconditioned subjects resulted in 7 of those 10 patients having otherwise normal recovery indices. Therefore, modeling pH~i~ recovery allows characterization of the entire pH~i~ recovery and detects altered proton handling in MM patients, including those with otherwise normal recovery indices. Magn Reson Med 46:870–878, 2001. © 2001 Wiley‐Liss, Inc.