Biochemical Characteristics of Glycerol Extracted Myocardial Fibers

Abstract

Glycerol extracted dog ventricle fiber bundles exhibited a pH optimum of 9.0 in a glycine-buffered KC1 medium when stimulated to isometric contraction with ATP (adenosine triphosphate). A definite optimum of 4 xl0-3 [image] ATP was found for contraction of the muscle model with probably substrate inhibition of the response at higher concentrations. The rate and magnitude of the response of the system to uridine triphosphate was equal to that observed when ATP was used to stimulate tension development. Mg showed an optimum concentration of 5 x 10-3 [image], while the Ca optimum was 10-4 [image] Na inhibited the development of tension in all concentrations tested. Data are interpreted as supporting in part the electrostatic-entropic scheme for muscular activity proposed by Morales and Botts.