Measurement of lactate in acutely ischemic rat kidneys using magnetic resonance spectroscopy

Quantification of lactate in the kidney by 1H magnetic resonance spectroscopy (MRS) is a difficult task because of the presence of large amounts of peri-renal fat. When an editing scheme is used to detect lactate that filters out all resonances except lactate, there is no suitable metabolite to serve as an internal standard. In this study, the authors evaluate the potential of MRS to measure the absolute lactate concentration in rat kidneys during acute ischemia using MRS.

The authors propose a method based on a double resonance lactate editing scheme used in combination with the fully relaxed water peak as an internal standard. Experiments were performed on the left kidney rendered ischemic in eight rats.

Renal lactate concentrations measured by MRS were compared with values derived from chemical analysis. The mean (+/- standard deviation) renal lactate concentrations measured by MRS and determined chemically were 12 +/- 1.2 umol/g, and 12.94 +/- 1.07 umol/g wet weight, respectively. The coefficient of variation for paired observations was 2.96%, indicating excellent agreement between the two methods used for measuring lactate.

The study results demonstrate that it is possible to assess the lactate concentration in a rat model of ischemic kidney with MRS and suggest that the total lactate pool is detectable by this method under these experimental conditions.