The influence of potassium and chloride ions on the membrane potential of single muscle fibres

Abstract

The most widely accepted theory of the restirng potential of muscle is that the electrical potential difference between the inside and outside of a muscle fibre arises from the concentration gradients of the potassium and chloride ions. If we follow Boyle & Conway (1941), the membrane is assumed to be permeable to K and Cl but to be impermeable or sparingly permeable to other ions. Since K is more concentrated inside and Cl is more concentrated outside, the interior of the fibre should be electrically negative to the external solution. If K and Cl are distributed passively, the concentration ratios and the membrane potential under equilibrium conditions ought to conform to the relationwhere [ ]O and [ ]i indicate concentrations outside and inside the fibre, V is the internal potential, F is Faraday's constant, R is the gas constant and T is the absolute temperature. When the external potassium concentration is less than 10 mm agreement with equation (1) is not perfect, but at higher concentrations the relation seems to hold with considerable accuracy (Adrian, 1956;Conway, 1957). However, it is only possible to calculate the membrane potential by equation (1) when the concentrations of K and Cl inside the fibre have come into equilibrium with those in the external solution. In order to deal with other situations one must know the relative conductances or permeabilities of the two ions. Information on this point can be obtained by measuring the effect on membrane potential of sudden changes in the concentrations of K or Cl. Such experiments are difficult to interpret unless the effect of changing the external solution can be determined in a time which is so short that there is no alteration in the internal concentration of Cl or K. The present observations were carried out with single muscle fibres, with an

The influence of potassium, sodium and chloride on the membrane potential of the smooth muscle of taenia coli

“…Consequently the linear part of the relation between membrane potential and log [K]o continued to as low a range of external K+ as 6 mm. Thus, for a short period the relationship in this respect resembled that obtained in skeletal muscle (Hodgkin & Horowicz, 1959). However, 15 min IONS AND MEMBRANE POTENTIAL later the membrane potential in the low range of external K+ was less than in the presence of the normal external Na+ concentration (continuous line in Fig.…”

“…6. The relation between membrane potential and log [K] (Adrian, 1956(Adrian, , 1960Hodgkin & Horowicz, 1959), but in taenia col it extends to 30 mM [K]o.…”

“…In skeletal muscle Hodgkin & Horowicz (1959) observed the relation between membrane potential and log [K]0 in chloride-free sulphate solution. They found that in the non-linear part of the relation (from 1 to 10 mM) the membrane potential was affected by the Na permeability.…”

Depolarizing response of rat parathyroid cells to divalent cations.

“…Complete replacement of Cl-was done to test whether its presence was necessary for the voltage changes induced by Ca" and to avoid possible hysteresis in the response when studying the effects of alterations in external K + (Hodgkin and Horowicz, 1959) . The Ca" concentrations used in these solutions were higher than those used in the modified Krebs solution because high concentrations of glutamate decrease Ca" activity .…”

A voltage‐clamp analysis of inward (anomalous) rectification in mouse spinal sensory ganglion neurones.

“…The properties ofthe inward rectifier in muscle have since been examined in some detail (Hodgkin & Horowicz, 1959;Adrian & Freygang, 1962 a, b;Nakajima, Iwasaki & Obata, 1962;Almers, 1972;Standen & Stanfield, 1978a, b, 1980Hestrin, 1981) and it is known that the underlying conductance, which is relatively specific for K+ ions, increases with membrane potential hyperpolarization and varies with the extracellular K+ concentration as a function of the difference between the membrane and K+ equilibrium potentials (Hestrin, 1981;Leech & Stanfield, 1981). A similar conductance is present in a number of marine egg cell membranes (starfish: Hagiwara & Takahashi, 1974;sea-squirt: Miyazaki, Takahashi, Tsuda & Yoshii, 1974).…”