Figure 6. Alterations in H⁺ flux induced by the ionotropic glutamate analogue kainate.

A, responses from a single cell showing the alteration in H⁺ flux that occurred upon the addition of 1 ml of Ringer solution alone (R), then with solution containing kainate (final concentration, 20 μm), and upon further addition of glutamate to a final concentration of 1 mm. Asterisks show recordings obtained with the electrode moved to a background location 250 μm away from the cell. B, average responses to kainate obtained from eight cells. C, responses from a single horizontal cell to 1 ml additions of normal saline solution and kainate (final concentration, 20 μm) in the presence of 100 μm CNQX. Asterisk again indicates recording obtained 250 μm from the cell. D, metabotropic glutamate receptor analogues did not alter H⁺ flux measured from horizontal cells. Responses obtained from a single cell to 1 ml normal extracellular solution and 1 ml solutions containing DHPG (final concentration, 100 μm) and 1 mm glutamate. Neither saline solution alone nor DHPG altered H⁺ flux, while glutamate produced a significant alteration in the measured signal.