Fig. 5.

Cs⁺ does not suppress increase in excitability initiated by 1 mM Ba²⁺. Excitability curves summarize the effect of Ba²⁺ on excitability for 12 cells kept in control solution, 13 cells bathed in a solution containing 2.5 mM Cs⁺, and 11 cells bathed in a solution containing 10 μM ZD7288 (7 cells) or 100 μM ZD7288 (4 cells). Values are means ± SE of number of action potentials generated by a 1-s depolarizing current pulse at multiple stimulus intensities, with lines fit with a linear regression. Slopes were significantly greater in cells exposed to Ba²⁺ alone and Ba²⁺ + Cs⁺ (18.38 ± 1.4 vs. 29.23 ± 1.82) than in cells exposed to Ba²⁺ + ZD7288 (6.45 ± 0.74, P < 0.001).