Figure 10. Kainate acidifies the intracellular milieu of skate horizontal cells. Intracellular pH levels were monitored using the pH indicator dye BCECF.

A, kainate (20 μm) produced a decrease in the ratio of fluorescence induced by stimulation with 488 and 460 nm light when cells were bathed in normal extracellular solution containing 4 mm calcium. Responses labelled pH 7, 9 and 5 are calibrations performed on the same cell bathed in nigericin. B, recording from a different horizontal cell showing that kainate does not alter intracellular pH when the solution lacks extracellular calcium.