THE EFFECT OF AN ADP ANALOG ON ISOMETRIC FORCE AND ATPase ACTIVITY OF ACTIVE MUSCLE FIBERS
نویسندگان
چکیده
The role played by ADP in modulating cross-bridge function has been difficult to study, as it is hard to buffer ADP concentration in skinned muscle preparations. To solve this, we used an analog of ADP, spin-labeled ADP (SL-ADP). SL-ADP binds tightly to myosin but is a very poor substrate for creatine kinase or pyruvate kinase. Thus, ATP can be regenerated allowing well-defined concentrations of both ATP and SL-ADP. We measured isometric ATPase rate and isometric tension as a function of both [SL-ADP], 0.1-2 mM, and [ATP], 0.05-0.5 mM, in skinned rabbit psoas muscle, simulating fresh or fatigued states. Saturating levels of SL-ADP increased isometric tension (by P'), the absolute value of P' being nearly constant, ~ 0.04 N.mm-2 , in variable ATP levels, pH 7.
منابع مشابه
Effect of an ADP analog on isometric force and ATPase activity of active muscle fibers.
The role played by ADP in modulating cross-bridge function has been difficult to study, because it is hard to buffer ADP concentration in skinned muscle preparations. To solve this, we used an analog of ADP, spin-labeled ADP (SL-ADP). SL-ADP binds tightly to myosin but is a very poor substrate for creatine kinase or pyruvate kinase. Thus ATP can be regenerated, allowing well-defined concentrati...
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