Kinetics of RRP replesnishment increase during development.

<p>(<b>A</b>) Recording examples of I_Ca and ΔC_m responses during a paired-pulse protocol (two consecutive 100 ms steps from -90 mV to -10 mV separated by 200 ms) at E12 and P2 in apical and basal tall HCs. (<b>B</b>) Comparative paired-pulse recovery (% of first response) at E10 (n = 7), E12 (n = 8), E16 (n = 7) and P2 (n = 4). Recordings were made with an intracellular Ca²⁺ buffer of 0.5 mM EGTA. Note a larger depression in immature pre-hearing HCs E10–E13 as compared to P2 mature HCs. Asterisks indicate a statistical difference with p<0.01. (<b>C</b>) Comparative kinetics of RRP recovery in E12 and E16 apical HCs when varying the inter-pulse time in the paired-pulse protocol. In immature E12 HCs, data points were best fitted with two exponentials with time constants of 800 ms and 6 s (n = 5). In E16 HCs (n = 5), data points were best fitted with a single exponential with time constant of 680 ms. (<b>D</b>) During the paired-pulse protocol, in E12 apical HCs, RRP and I_Ca showed similar depression or slow kinetics of recovery.