The effect of amiloride on the resting potential and the electrical constants of frog skeletal muscle fibres.

Estrada, Francisco; Sánchez, Jorge A.

doi:10.1113/jphysiol.1991.sp018451

Cited by 3 publications

(8 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In order to determine whether the increase in the amplitude of K + contractures is the result of changes in the resting potential (Er) of muscle fibres by low external Na +, we measured E r and found only minor changes, although statistically significant (p < 0.001), confirming previous results (Estrada & Sanchez, 1991). E r changed from -89.7 q-0.7mV (n =24) to -93.4 q-0.7mV (n = 32) when Na + was replaced by NMG in a SO24 -solution containing 2.5 mM K +.…”

Section: Potentiation Of K + Contractures By Na+-free Solutionssupporting

confidence: 76%

“…2), this corresponds to a shift of -11 mV. A similar shift of -12 mV in the threshold of our K + contracture experiments is calculated by using the Goldman-Hodgkin-Katz Equation (see Hodgkin & Horowicz, 1959) with an estimated [K+]~ of 127.7 mM (Estrada & Sanchez, 1991). This yields values of -60 mV and -48 mV for the threshold in Na § and in NMG respectively.…”

Section: Sodium Ions and Contractionmentioning

confidence: 98%

“…In these experiments, charge movement was elicited by command pulses to -40 mV. This potential (Estrada & Sanchez, 1991). In contrast to the mechanical experiments shown in Fig.…”

Section: -Gmentioning

confidence: 98%

See 2 more Smart Citations

Effect of sodium deprivation on contraction and charge movement in frog skeletal muscle fibres

García¹,

Díaz

Godı́nez

et al. 1992

J Muscle Res Cell Motil

View full text Add to dashboard Cite

Measurements of isometric tension were performed in single twitch skeletal muscle fibres and the effect of extracellular Na+ removal on contraction was investigated. Na+ withdrawal brought about an increase in the amplitude of K+ contractures and their time course became faster. The potentiation of K+ contractures depended strongly on extracellular Ca2+ and developed slowly following an exponential time course with a time constant of approximately 8 min. Removal of extracellular Na+ greatly increased the amplitude of caffeine contractures and lowered its threshold: caffeine (0.5 mM) had no effect on resting tension in Ringer's but produced contractures in Na(+)-free solutions. Intramembrane charge movement (charge 1) was monitored in contracting voltage-clamped segments of frog skeletal muscle fibres using the triple-Vaseline-gap technique. Movement of charge 1 did not depend on the presence of extracellular Na+. However, the mechanical threshold decreased by approximately 10 mV at several pulse durations and the charge which produced just detectable contractions decreased by approximately 5 nC microF-1 in the absence of extracellular Na+. Intracellular heparin (40 mg ml-1) increased the mechanical threshold by approximately 20 mV without affecting the movement of charge 1. The effect of Na(+)-free solutions on the mechanical threshold was additive to that of heparin. It is concluded that the effects of Na(+)-withdrawal on contraction take place at a location beyond the voltage sensor of excitation-contraction coupling.

show abstract

Section: Potentiation Of K + Contractures By Na+-free Solutionssupporting

confidence: 76%

Section: Sodium Ions and Contractionmentioning

confidence: 98%

See 1 more Smart Citation

Effect of sodium deprivation on contraction and charge movement in frog skeletal muscle fibres

García¹,

Díaz

Godı́nez

et al. 1992

J Muscle Res Cell Motil

View full text Add to dashboard Cite

show abstract

“…This conflicts with the recent work of Estrada & Sanchez (1991) who found a hyperpolarization as high as 12 mV in the presence of amiloride (10 3 M).…”

Section: Does Heptaminol Act On Ionic Currents?contrasting

confidence: 90%

“…It must be added that in our experimental conditions (performed in the presence of TTX) amiloride or EIPA had no action on the holding current and on the current during the depolarizing pulses. This conflicts with the recent work of Estrada & Sanchez (1991) who found a hyperpolarization as high as 12 mV in the presence of amiloride (10 3 M).…”

Section: Does Heptaminol Act Via An Internal Alkalinization?contrasting

confidence: 90%

Action of heptaminol hydrochloride on contractile properties in frog isolated twitch muscle fibre

Allard

Jacquemond

Lemtiri‐Chlieh

et al. 1991

British J Pharmacology

View full text Add to dashboard Cite

1 Heptaminol stopped or delayed the progressive decline in tension which characterizes the phenomenon of fatigue in frog isolated twitch muscle fibre. 2 Heptaminol had no action on the sodium, potassium and calcium voltage-dependent ionic conductances.3 The hypothesis of an action via an internal alkalinization was tested by comparison with the action of NH4Cl. Both substances increased the tension. 4 The action of heptaminol was suppressed in sodium-free (TRIS) solution or in the presence of amiloride while the action of NH4Cl was always observed. 5 These results could be explained by a stimulation of the Na/H antiport by heptaminol.

show abstract

Stretch-activated ion channels contribute to membrane depolarization after eccentric contractions

McBride

Stockert²,

Gorin

et al. 2000

Journal of Applied Physiology

101

View full text Add to dashboard Cite

We tested the hypothesis that eccentric contractions activate mechanosensitive or stretch-activated ion channels (SAC) in skeletal muscles, producing increased cation conductance. Resting membrane potentials and contractile function were measured in rat tibialis anterior muscles after single or multiple exposures to a series of eccentric contractions. Each exposure produced a significant and prolonged (>24 h) membrane depolarization in exercised muscle fibers. The magnitude and duration of the depolarization were related to the number of contractions. Membrane depolarization was due primarily to an increase in Na(+) influx, because the estimated Na(+)-to-K(+) permeability ratio was increased in exercised muscles and resting membrane potentials could be partially repolarized by substituting an impermeant cation for extracellular Na(+) concentration. Neither the Na(+)/H(+) antiport inhibitor amiloride nor the fast Na(+) channel blocker TTX had a significant effect on the depolarization. In contrast, addition of either of two nonselective SAC inhibitors, streptomycin or Gd(3+), produced significant membrane repolarization. The results suggest that muscle fibers experience prolonged depolarization after eccentric contractions due, principally, to the activation of Na(+)-selective SAC.

show abstract

The effect of amiloride on the resting potential and the electrical constants of frog skeletal muscle fibres.

Cited by 3 publications

References 31 publications

Effect of sodium deprivation on contraction and charge movement in frog skeletal muscle fibres

Effect of sodium deprivation on contraction and charge movement in frog skeletal muscle fibres

Action of heptaminol hydrochloride on contractile properties in frog isolated twitch muscle fibre

Stretch-activated ion channels contribute to membrane depolarization after eccentric contractions

Contact Info

Product

Resources

About