Biophysical Journal 61: 1470-1479 (1992)
© 1992 the Biophysical Society

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by al-Baldawi, N F Articles by Abercrombie, R F Search for Related Content PubMed PubMed Citation Articles by al-Baldawi, N F Articles by Abercrombie, R F

Cytoplasmic hydrogen ion diffusion coefficient.

Department of Physiology, Emory University School of Medicine, Atlanta, Georgia 30322.

ABSTRACT

The apparent cytoplasmic proton diffusion coefficient was measured using pH electrodes and samples of cytoplasm extracted from the giant neuron of a marine invertebrate. By suddenly changing the pH at one surface of the sample and recording the relaxation of pH within the sample, an apparent diffusion coefficient of 1.4 +/- 0.5 x 10(-6) cm2/s (N = 7) was measured in the acidic or neutral range of pH (6.0-7.2). This value is approximately 5x lower than the diffusion coefficient of the mobile pH buffers (approximately 8 x 10(-6) cm2/s) and approximately 68x lower than the diffusion coefficient of the hydronium ion (93 x 10(-6) cm2/s). A mobile pH buffer (approximately 15% of the buffering power) and an immobile buffer (approximately 85% of the buffering power) could quantitatively account for the results at acidic or neutral pH. At alkaline pH (8.2-8.6), the apparent proton diffusion coefficient increased to 4.1 +/- 0.8 x 10(-6) cm2/s (N = 7). This larger diffusion coefficient at alkaline pH could be explained quantitatively by the enhanced buffering power of the mobile amino acids. Under the conditions of these experiments, it is unlikely that hydroxide movement influences the apparent hydrogen ion diffusion coefficient.

This article has been cited by other articles:

				P. Swietach and R. D Vaughan-Jones Relationship between intracellular pH and proton mobility in rat and guinea-pig ventricular myocytes J. Physiol., August 1, 2005; 566(3): 793 - 806. [Abstract] [Full Text] [PDF]

				P. Swietach, C.-H. Leem, K. W. Spitzer, and R. D. Vaughan-Jones Experimental Generation and Computational Modeling of Intracellular pH Gradients in Cardiac Myocytes Biophys. J., April 1, 2005; 88(4): 3018 - 3037. [Abstract] [Full Text] [PDF]

				C. Geers and G. Gros Carbon Dioxide Transport and Carbonic Anhydrase in Blood and Muscle Physiol Rev, April 1, 2000; 80(2): 681 - 715. [Abstract] [Full Text] [PDF]

				K. W. Spitzer, P. R. Ershler, R. L. Skolnick, and R. D. Vaughan-Jones Generation of intracellular pH gradients in single cardiac myocytes with a microperfusion system Am J Physiol Heart Circ Physiol, April 1, 2000; 278(4): H1371 - H1382. [Abstract] [Full Text] [PDF]

				J.A. Feijo, J. Sainhas, G.R. Hackett, J.G. Kunkel, and P.K. Hepler Growing Pollen Tubes Possess a Constitutive Alkaline Band in the Clear Zone and a Growth-dependent Acidic Tip J. Cell Biol., February 8, 1999; 144(3): 483 - 496. [Abstract] [Full Text] [PDF]

				R. Parton, S Fischer, R Malho, O Papasouliotis, T. Jelitto, T Leonard, and N. Read Pronounced cytoplasmic pH gradients are not required for tip growth in plant and fungal cells J. Cell Sci., January 5, 1997; 110(10): 1187 - 1198. [Abstract] [PDF]

				C. J. Schwiening and D. Willoughby Depolarization-induced pH microdomains and their relationship to calcium transients in isolated snail neurones J. Physiol., January 9, 2002; 538(2): 371 - 382. [Abstract] [Full Text] [PDF]