This study evaluates the effects of free Mg2+ concentration on submaximum isometric tension generated by single skinned fibers from semitendinosus muscles of the frog. Increases in Mg2+ concentration are accompanied by decreases in the submaximum isometric tension generated in bathing solutions which have the same Ca2+ concentration and same ionic strength. The effects of changes in MgATP2- and ATP4- concentration were separated from those of Mg2+ and were found to be very small in comparison to those of Mg2+ concentration. The Mg2+ concentrations used in two sets of solutions were 0.3, 1, and 2 mM. In one set of solutions MgATP2- concentration changed from approximately 2 to 12 mM and in the other set of solutions ATP4- concentration changed from approximately 10-4 to 1.6×10-5 M. Ionic strength was found to have a significant inverse effect on submaximal isometric tension.
ASJC Scopus subject areas
- Cell Biology