Serial in vivo spectroscopic nuclear magnetic resonance imaging of lactate and extracellular ph in rat gliomas shows redistribution of protons away from sites of glycolysis

Provent, P. et al. (2007) Serial in vivo spectroscopic nuclear magnetic resonance imaging of lactate and extracellular ph in rat gliomas shows redistribution of protons away from sites of glycolysis. Cancer Research, 67(16), pp. 7638-7645. (doi: 10.1158/0008-5472.CAN-06-3459)

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Publisher's URL: http://dx.doi.org/10.1158/0008-5472.CAN-06-3459

Abstract

The acidity of the tumor microenvironment aids tumor growth, and mechanisms causing it are targets for potential therapies. We have imaged extracellular pH (pHe) in C6 cell gliomas in rat brain using <sup>1</sup>H magnetic resonance spectroscopy in vivo. We used a new probe molecule, ISUCA [(±)2-(imidazol-1-yl)succinic acid], and fast imaging techniques, with spiral acquisition in k-space. We obtained a map of metabolites [136 ms echo time (TE)] and then infused ISUCA in a femoral vein (25 mmol/kg body weight over 110 min) and obtained two consecutive images of pHe within the tumor (40 ms TE, each acquisition taking 25 min). pHe (where ISUCA was present) ranged from 6.5 to 7.5 in voxels of 0.75 μL and did not change detectably when [ISUCA] increased. Infusion of glucose (0.2 mmol/kg•min) decreased tumor pHe by, on average, 0.150 (SE, 0.007; P < 0.0001, 524 voxels in four rats) and increased the mean area of measurable lactate peaks by 54.4 ± 3.4% (P < 0.0001, 287 voxels). However, voxel-by-voxel analysis showed that, both before and during glucose infusion, the distributions of lactate and extracellular acidity were very different. In tumor voxels where both could be measured, the glucose-induced increase in lactate showed no spatial correlation with the decrease in pHe. We suggest that, although glycolysis is the main source of protons, distributed sites of proton influx and efflux cause pHe to be acidic at sites remote from lactate production.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Coles, Dr Jonathan
Authors: Provent, P., Benito, M., Hiba, B., Farion, R., Lopez-Larrubia, P., Ballesteros, P., Remy, C., Segebarth, C., Cerdan, S., Coles, J. A., and Garcia-Martin, M. L.
College/School:College of Medical Veterinary and Life Sciences > Institute of Infection Immunity and Inflammation
Journal Name:Cancer Research
Publisher:American Association for Cancer Research
ISSN:0008-5472
ISSN (Online):1538-7445

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