title: Contraction of glycerinated muscle fibers as a function of the ATP concentration.
abstract: We have measured the force-velocity curves of glycerinated rabbit psoas fibers over a range of ATP concentration from 2.5 microM to 5 mM. As the ATP concentration is increased, the isometric tension increases to a maximum around 50 microM, then decreases to a plateau at 70% of the maximum by 1 mM ATP. At low ATP concentrations the maximum velocity of contraction is low and increases with increasing ATP, reaching a plateau at approximately 2 lengths per second by 1 mM ATP. Our studies suggest that the binding of ATP dissociates the myosin head from actin in the contracting muscle, a reaction similar to that seen in solution. We have constructed models of the actin-myosin-nucleotide interactions based on a kinetic scheme derived from solution studies. The fit of these models to the data shows that the rates of some reactions in the fiber must be considerably different from the rates of the analogous reactions in solution. The data is best fit by models in which head attachment occurs rapidly at the beginning of a power stroke, head detachment occurs rapidly at the end of the power stroke, and the force produced by a myosin head in a power stroke is independent of velocity.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D003402:Creatine Kinase / Q000378:metabolism; D007700:Kinetics; D008433:Mathematics; D009119:Muscle Contraction / Q000187:drug effects*; D009132:Muscles / Q000502:physiology; D011817:Rabbits
chemical_list: D000255:Adenosine Triphosphate; D003402:Creatine Kinase
references.citation: J Physiol. 1923 Dec 28;58(2-3):175-203
references.pmid: 16993652
references.citation: Proc R Soc Lond B Biol Sci. 1964 Mar 17;159:589-95
references.pmid: 14132964
references.citation: Prog Biophys Biophys Chem. 1957;7:255-318
references.pmid: 13485191
references.citation: J Physiol. 1977 Jul;269(2):255-72
references.pmid: 302331
references.citation: Anal Biochem. 1979 Jan 15;92(2):375-82
references.pmid: 220891
references.citation: Biochemistry. 1976 Dec 28;15(26):5818-26
references.pmid: 12793
references.citation: Biochemistry. 1976 Dec 28;15(26):5813-7
references.pmid: 12792
references.citation: Biochemistry. 1978 Dec 12;17(25):5431-9
references.pmid: 153150
references.citation: J Biochem. 1977 Sep;82(3):801-12
references.pmid: 144122
references.citation: Biochem J. 1978 Apr 1;171(1):165-75
references.pmid: 148277
references.citation: Prog Biophys Mol Biol. 1978;33(1):55-82
references.pmid: 146885
references.citation: J Mol Biol. 1978 Apr 15;120(3):361-73
references.pmid: 148513
references.citation: J Gen Physiol. 1977 Jan;69(1):37-55
references.pmid: 137958
references.citation: Science. 1978 Mar 17;199(4334):1212-3
references.pmid: 415364
references.citation: J Mechanochem Cell Motil. 1977 Sep;4(3):205-32
references.pmid: 753901
references.citation: Biophys J. 1978 Apr;22(1):97-103
references.pmid: 638228
references.citation: Biochemistry. 1977 Oct 4;16(20):4398-402
references.pmid: 911763
references.citation: J Theor Biol. 1974 Feb;43(2):313-28
references.pmid: 4274195
references.citation: J Physiol. 1974 May;238(3):455-72
references.pmid: 4546948
references.citation: Biochemistry. 1969 Mar;8(3):811-9
references.pmid: 4305486
references.citation: Biochemistry. 1971 Dec 7;10(25):4617-24
references.pmid: 4258719
references.citation: Prog Biophys Mol Biol. 1974;28:267-340
references.pmid: 4617248
references.citation: Biochemistry. 1976 Jul 27;15(15):3244-53
references.pmid: 133714
references.citation: Biophys J. 1974 Jul;14(7):546-62
references.pmid: 4836669
references.citation: J Theor Biol. 1975 Feb;49(2):425-9
references.pmid: 123613
references.citation: J Gen Physiol. 1976 Sep;68(3):267-80
references.pmid: 821913
references.citation: J Exp Biol. 1975 Jun;62(3):701-19
references.pmid: 1206349
references.citation: Biophys J. 1975 Apr;15(4):335-72
references.pmid: 1125390