PMID: 9662703Jul 15, 1998Paper

Biophysical model for organic acid excretion in Ascaris suum

Molecular and Biochemical Parasitology
Kevin L BlairD P Thompson

Abstract

To develop a model for the mechanisms of organic acid excretion in nematodes, we measured the concentrations of volatile fatty acids (VFAs), pH and electrical potentials across hypodermal and muscle membranes and across the composite body wall (consisting of hypodermis, muscle and cuticle) of Ascaris suum using standard chromatographic and microelectrode recording techniques. In incubates containing one parasite in 20 ml modified Ascaris Ringer's solution, the level of combined VFAs excreted into the medium increased linearly for about 18 h, then plateaued at a concentration of 4.2 mM; the medium acidified rapidly to a plateau at about pH 5.0 within 4-6 h. Following 24 h incubations, the concentrations of VFAs in the hypodermis, muscle, and pseudocoelomic compartments were 62.4 +/- 8.1, 62.3 +/- 7.8 and 74.4 +/- 3.2 mM, respectively. The pseudocoelomic fluid was more acidic (pH 6.52 +/- 0.06) than the hypodermis (pH 6.78 +/- 0.03) or muscle (pH 6.77 +/- 0.03). These data and the electrical potentials across hypodermal (-57.9 +/- 6.3 mV) and muscle (-30.3 +/- 0.8 mV) membranes were used to determine the equilibrium concentrations for protonated (HVFA) and anionic (VFA-) forms of the acids across these membranes and across the cu...Continue Reading

References

Sep 8, 1992·Molecular and Cellular Biochemistry·N A WolffJ B Pritchard
Jul 1, 1992·Molecular and Biochemical Parasitology·S M SimsD P Thompson
Jun 1, 1990·Molecular and Biochemical Parasitology·N F HoD P Thompson
Nov 1, 1989·The Journal of Membrane Biology·A SchmidH Gögelein
Dec 1, 1989·Quarterly Journal of Experimental Physiology : an International Journal of the Physiological Society·J del CastilloJ Serrato
Oct 1, 1986·The Journal of Clinical Investigation·J L Seifter, P S Aronson
Sep 1, 1971·The Journal of Physiology·A F Brading, P C Caldwell
Jan 1, 1996·International Journal for Parasitology·S M SimsD P Thompson
Jun 20, 2003·Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology·Kevin L BlairDavid P Thompson

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Citations

Jun 20, 2003·Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology·Kevin L BlairDavid P Thompson
May 2, 2007·BMC Evolutionary Biology·Jeremy C BrownlieElizabeth A McGraw

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