Electrophysiological membrane properties of the frog muscle fibre: effects of detergents in the triton series.

The effect of the nonionic detergent Triton X-100 on the membrane properties of frog sartorius muscle fibres was studied using intracellular microelectrode technique. The effect of Triton X-100 was compared with that of Triton X-45 and Triton N-101. At 40 muM Triton X-100 had little effect on the specific membrane resistance (Rm), membrane capacitance (Cm) and the resting membrane potential (Er) while the action potential (AP) was markedly reduced. At 160 muM AP was completely abolished and Er was diminished linearily with time. The effect on the maximum rate of rise (VA) of the AP was dose-dependent and the apparent dissociation constant (KD app) and K(D) were found to be about 40 muM. The Hill coefficient was 1.6 indicating a deviation from a first order reaction. The effect of Triton X-100 on Er may be accounted for by a reduction of the Na--K pumping activity. The effect of Triton X-100 on the AP is suggested to be due to a perturbation of a protein-system either by a drug-receptor interaction involving two or more sites, or an unspecific binding of Triton X-100 to hydrophobic loci on the protein.