Intracellular diffusion in the presence of mobile buffers. Application to proton movement in muscle

M. Irving, James Maylie, N. L. Sizto, W. K. Chandler

Research output: Contribution to journalArticle

51 Citations (Scopus)

Abstract

Junge and McLaughlin (1987) derived an expression for the apparent diffusion constant of protons in the presence of both mobile and immobile buffers. Their derivation applies only to cases in which the values of pH are considerably greater than the largest pK of the individual buffers, a condition that is not expected to hold in skeletal muscle or many other cell types. Here we show that, if the pH gradients are small, the same expression for the apparent diffusion constant of protons can be derived without such constraints on the values of the pK's. The derivation is general and can be used to estimate the apparent diffusion constant of any substance that diffuses in the presence of both mobile and immobile buffers. The apparent diffusion constant of protons is estimated to be 1-2 x 10-6 cm2/s at 18°C inside intact frog twitch muscle fibers. It may be smaller inside cut fibers, owing to a reduction in the concentration of mobile myoplasmic buffers, so that in this preparation a pH gradient, if established within a sarcomere following action potential stimulation, could last 10 ms or longer after stimulation ceased.

Original languageEnglish (US)
Pages (from-to)717-721
Number of pages5
JournalBiophysical Journal
Volume57
Issue number4
StatePublished - 1990
Externally publishedYes

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Protons
Buffers
Muscles
Proton-Motive Force
Sarcomeres
Anura
Action Potentials
Skeletal Muscle

ASJC Scopus subject areas

  • Biophysics

Cite this

Intracellular diffusion in the presence of mobile buffers. Application to proton movement in muscle. / Irving, M.; Maylie, James; Sizto, N. L.; Chandler, W. K.

In: Biophysical Journal, Vol. 57, No. 4, 1990, p. 717-721.

Research output: Contribution to journalArticle

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