Figure 4. E_Gly changes during development.

E_Gly was determined from LSO neurones of different ages recorded in gramicidin perforated-patch configuration. A-C, the upper panels show examples of glycine-evoked currents obtained at different step potentials in a P3, a P7 and a P10 neurone. The lower panels depict the corresponding I-V relations, where E_Gly amounted to −38.4 mV (P3), −62.4 mV (P7) and −79.7 mV (P10). The current families and I-V relations shown here were obtained with the ‘up’ voltage protocol. In all cases, care was taken to unambiguously determine E_Gly (see Methods for details). V_s =−70 to −20 mV in A, −80 to −20 mV in B and −90 to −40 mV in C. D, E_Gly values from LSO neurones (n = 57, P1-11) were plotted against age; open circles mark results from the three neurones shown in A-C. An age-related negative shift of E_Gly was seen. E, grouped data show a highly significant shift of E_Gly from −46.8 ± 1.8 mV at P1-4 (n = 28) to −67.6 ± 3.3 mV at P5-8 (n = 10) to −82.2 ± 4.1 mV at P9-11 (n = 18, ▪, ANOVA, P < 0.001). A parallel shift in V_m was not observed (□); a significant difference was found only between P1-4 and P9-11 (ANOVA and Tukey's HSD post hoc test, P < 0.05). Average V_m values were −58.3 ± 0.8 mV at P1-4 (n = 24), −63.0 ± 2.4 mV at P5-8 (n = 9) and −62.7 ± 1.4 mV at P9-11 (n = 15).