Analytical Sciences

Comparison of the L-Glutamate Level in Mouse Hippocampal Slices under Tetraethylammonium Chloride Stimulation as Measured with a Glass Capillary Sensor and a Patch Sensor

Takayuki OKA, Yumiko TOMINAGA, Yuichiro WAKABAYASHI, Atsushi SHOJI, and Masao SUGAWARA

Department of Chemistry, College of Humanities and Sciences, Nihon University, Sakurajosui, Setagaya, Tokyo 156-8550, Japan

The concentration level of L-glutamate released from the region CA1 of mouse hippocampal slices under tetraethylammonium chloride (TEA) stimulation was measured by two independent methods, i.e., a glass capillary-based enzyme sensor and a patch sensor, and compared with each other for different slice preparations. In a submerged slice preparation, the sensors were positioned in bath solutions several tens µm above CA1, respectively. The sensors exhibited almost the same level of extra-slice L-glutamate concentration. When a capillary sensor was implanted in region CA1 at a depth of approximately 10 µm, the TEA-induced L-glutamate release pattern was very similar to those observed with the capillary sensor in a bath use. The concentration level of intra-slice (extracellular) L-glutamate was found to be in the range from 6 to 10 µM, which was significantly larger than that of the extra-slice one. These results demonstrate that L-glutamate released from each neuronal region inevitably diffuses out of the slices, and the extra-slice L-glutamate level reflects the extracellular one.

J-STAGE: View this article in J-STAGE