Multiple equilibria of cations with metabolites in muscle
bioenergetics.
Kushmerick, Martin J.
Departments of Radiology, Bioengineering, and Physiology and
Biophysics, University of Washington, Seattle, WA
APStracts 3:0333C, 1996.
We evaluated the multiple ionic forms of metabolites at 37 degrees C
for four reactions important in muscle contraction and recovery: 1.
ATPase, 2. Creatine kinase, 3. Lohmann reaction and 4. the Lohmann
reaction reversed by coupling to glycogenolysis and glycolysis.
Solution of the system of equations defining the multiple equilibria
of the proton and cation complexes gives the concentration of each
ionic form and a value for the proton stoichiometry for each
reaction. The proton stoichiometric coefficients are unique for each
reaction and are a function of pH because of differential binding of
Mg2+ and K+ to adenine nucleotides, PCr and inorganic phosphate and
because of different pKa values for the metabolites. These results
show the need to consider the binding of K+ in addition to the
previously documented effects of Mg2+ in the cytoplasmic mileau. We
used commercially available software to show that related problems
can be calculated readily on personal computers in applications
similar to those described here.
Received 18 June 1996; accepted in final form 18 October 1996.
APS Manuscript Number C348-6.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 13 November 1996