Troponin replacement in permeabilized cardiac muscle. Reversible extraction of troponin I by incubation with vanadate.
Calcium-dependent regulation of tension and ATPase activity in permeabilized porcine ventricular muscle was lost after incubation with 10 mM vanadate. After transfer from vanadate to a vanadate-free, low-Ca2+ solution (pCa greater than 8), the permeabilized muscle produced 84.8% +/- 20.1% (+/- S.D., n = 98) of the isometric force elicited by high Ca2+ (pCa approximately 4.5) prior to incubation with vanadate. Transfer back to a high Ca2+ solution elicited no additional force (83.2% +/- 18.7% of control force). SDS-PAGE and immunoblot analysis of fibers and solutions demonstrated substantial extraction (greater than 90%) of Troponin I (TnI). Calcium dependence was restored after incubation with solutions containing either whole cardiac troponin or a combination of TnI and troponin C subunits. This reversible extraction of troponin directly demonstrates the role of TnI in the regulation of striated muscle contractility and permits specific substitution of the native TnI with exogenously supplied protein.
Strauss
J D
JD
II Physiologisches Institut, Universität Heidelberg, Germany.
Zeugner
C
C
Van Eyk
J E
JE
Bletz
C
C
Troschka
M
M
Rüegg
J C
JC
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002463:Cell Membrane Permeability; D006321:Heart / Q000187:drug effects; D006352:Heart Ventricles; D009119:Muscle Contraction / Q000502:physiology*; D009206:Myocardium / Q000378:metabolism*; D013552:Swine; D014336:Troponin / Q000378:metabolism*; D019210:Troponin I; D014638:Vanadates / Q000494:pharmacology
D014336:Troponin; D019210:Troponin I; D014638:Vanadates; D002118:Calcium