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Table 1.
Effects of pHi, pHo, and [Ca2+]o on channel N′Po/Vm relationships
ConditionKV1/2N′Po minN′Po maxR2
 mV mV % %  
pHi 7.0 (5) 20.8 ± 3.9 41.7 ± 8.4 19.4 ± 6a 111.0 ± 8.2 0.961 ± 0.027 
pHi 7.4 (7) 19.0 ± 6.1 28.8 ± 8.4 19.6 ± 4.5a 106.7 ± 8.2 0.905 ± 0.022 
pHi 7.6 (5) 22.9 ± 10.1 29.6 ± 5.9 38.4 ± 11.3 106.4 ± 4.4 0.953 ± 0.016 
pHi 7.8 (5) 20.4 ± 4.6 32.8 ± 4.9 47.3 ± 3.3a 104.8 ± 1.7 0.945 ± 0.069 
pHo 6.6 (5) 19.5 ± 6.2 58.0 ± 5.1b 33.1 ± 3.3 124.1 ± 12 0.934 ± 0.016 
pHo 7.4 (5) 13.1 ± 2.4 33.0 ± 8.5 35.0 ± 3 105.0 ± 3.2 0.890 ± 0.03 
pHo 8.0 (4) 23.3 ± 6.5 20.8 ± 4.6 37.0 ± 4.5 109.8 ± 3 0.927 ± 0.04 
[Ca2+]o 0 mM (5) 21.2 ± 5.1 34.3 ± 12.6 10.4 ± 2.5 119.5 ± 11.2 0.979 ± 0.015 
[Ca2+]o 5 mM (4) 29.1 ± 5.1 31.4 ± 11.3 6.9 ± 5.3 118.7 ± 11.8 0.965 ± 0.012 
ConditionKV1/2N′Po minN′Po maxR2
 mV mV % %  
pHi 7.0 (5) 20.8 ± 3.9 41.7 ± 8.4 19.4 ± 6a 111.0 ± 8.2 0.961 ± 0.027 
pHi 7.4 (7) 19.0 ± 6.1 28.8 ± 8.4 19.6 ± 4.5a 106.7 ± 8.2 0.905 ± 0.022 
pHi 7.6 (5) 22.9 ± 10.1 29.6 ± 5.9 38.4 ± 11.3 106.4 ± 4.4 0.953 ± 0.016 
pHi 7.8 (5) 20.4 ± 4.6 32.8 ± 4.9 47.3 ± 3.3a 104.8 ± 1.7 0.945 ± 0.069 
pHo 6.6 (5) 19.5 ± 6.2 58.0 ± 5.1b 33.1 ± 3.3 124.1 ± 12 0.934 ± 0.016 
pHo 7.4 (5) 13.1 ± 2.4 33.0 ± 8.5 35.0 ± 3 105.0 ± 3.2 0.890 ± 0.03 
pHo 8.0 (4) 23.3 ± 6.5 20.8 ± 4.6 37.0 ± 4.5 109.8 ± 3 0.927 ± 0.04 
[Ca2+]o 0 mM (5) 21.2 ± 5.1 34.3 ± 12.6 10.4 ± 2.5 119.5 ± 11.2 0.979 ± 0.015 
[Ca2+]o 5 mM (4) 29.1 ± 5.1 31.4 ± 11.3 6.9 ± 5.3 118.7 ± 11.8 0.965 ± 0.012 

Mean parameters from Boltzmann fits (see Materials and methods) of individual N′Po/Vm relationships in the cell-excised inside-out configuration in the conditions given in the left column. In each condition, N′Po values were normalized to their respective values at Vm 80 mV. Data are given as means ± SEM for the number of fits indicated in parentheses. For each condition, a measure of the goodness of fit (R2) is also given. One-way ANOVA revealed significant differences between the N′Pomin means of pHi groups (P < 0.005) and between the V1/2 means of pHo groups (P < 0.01). Parameters under 0 and 5 mM [Ca2+]o were not statistically different (unpaired Student’s t test).

a

P < 0.01 versus pHi 7.8 (Holm-Šidák multiple comparison procedure).

b

P = 0.02 versus pHo 8.0 (Holm-Šidák multiple comparison procedure).

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