TABLE I .

Effect of pH on Electrical Properties of Muscle Fibers from Adult Rats at 4 and 11 mM K⁺

[K+]o	[Cl−]o	pH	n	Vm	λ	Rin	Diameter	Gm	GK +	GCl −
mM	mM			mV	mm	MΩ	μm	μS/cm2	μS/cm2	μS/cm2
4	127.4	7.4	10/19	−69 ± 1	0.89 ± 0.03	0.35 ± 0.02	55 ± 2	1017 ± 58
11	127.4	7.4	10/23	−52 ± 1	0.65 ± 0.02	0.20 ± 0.01	62 ± 2	2136 ± 150		1731 ± 151
11	0	7.4	9/28	−55 ± 1	1.45 ± 0.06	0.52 ± 0.02	57 ± 2	405 ± 20	405 ± 20
11	127.4	6.8	7/29	−52 ± 1	0.77 ± 0.03	0.28 ± 0.01	57 ± 2	1393 ± 56		938 ± 64
11	0	6.8	8/26	−53 ± 1	1.37 ± 0.07	0.51 ± 0.02	56 ± 2	455 ± 30	455 ± 30

Hyperpolarizing current pulses of 75 ms duration were injected through the current electrode, and the voltage electrode recorded the membrane responses at three to five locations in each fiber. ΔV_m/I ratios were plotted on a log scale against inter-electrode distance and fitted to a two-parameter exponentially decaying function, giving a straight line. The slope of the line was used to calculate the length constant, λ, and the ordinate intercept gave the input resistance, R_in (Fig. 2). Conductance was calculated from λ and R_in according to Boyd and Martin (1959) using an assumed internal resistivity (R_i) of 180 Ωcm. n gives muscles/fibers used in each group. Values are means ± SEM.