Vanadare and phosphate ions reduce tension and increase cross-bridge kinetics in chemically skinned heart muscle

Herzig, J. W.; Peterson, John W.; Rüegg, J. C.; Solaro, R. John

doi:10.1016/0304-4165(81)90392-5

Cited by 75 publications

(53 citation statements)

References 14 publications

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“…An elementary calculation shows that both activations generally rise much more steeply with increasing Z2 than does the corresponding analogue of the Langmuir adsorption isotherm, showing what is often referred to as "positive cooperativity." We also note thatJ' $ 1' and the ratio 41/J' generally increases with increasing Z2; i.e., the relative tension cost decreases with increasing activation, as is often but not always observed (10,11 [4] which was used instead of Eq. 3 for the calculation of Fig.…”

Section: The Modelmentioning

confidence: 69%

“…1B. That this approximation is reasonable is indicated by the qualitative similarity between measurements ofthe Ca2+ activation ofATPase in isometric fibers (10,11) and those in myofibrils (17).…”

Section: The Modelmentioning

confidence: 72%

“…As the concentration of Ca2' is raised, it is adsorbed onto troponin (1,8,9) and the reaction of crossbridges with actins is stimulated, resulting in increases in the stationary-state isometric force and ATPase in fibers (9)(10)(11) and an increase in ATPase in myofibrils (10). To take into account the promotion of crossbridge reaction with actins by Ca2' adsorption to troponin, we assume that when a Ca2" site is occupied and a nearest-neighbor actin is reacting with a crossbridge, there is an attractive (<O) free energy of interaction w12.…”

Section: The Modelmentioning

confidence: 99%

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Activation of thin-filament-regulated muscle by calcium ion: considerations based on nearest-neighbor lattice statistics.

Shiner¹,

Solaro

1982

Proc. Natl. Acad. Sci. U.S.A.

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We discuss the activation of thin-filament-regulated muscles by calcium ion in terms of a qualitative model based on nearest-neighbor lattice statistics. For the most part, the model takes into account only the essential features of the phenomenon-that there must be an interaction between calcium adsorption to troponin and crossbridge reaction with actin for calcium ion to activate contraction and that the relevant stationary states are nonequilibrium ones. Even so, the model predicts the following features which are seen experimentally but have generally not been considered in previous models: (i) the relative activations of stationary-state isometric force and ATPase are not equal; (ii) in general, neither activation of force nor that of ATPase is proportional to calcium adsorption to the activating sites; and (iii) the slopes of the relations between the activations and the logarithm of the calcium ion concentration generally depend on the necessary interaction between calcium ion adsorption and crossbridge reaction with actin. Thus, these relations show cooperative effects even if there is no interaction between calcium adsorption sites.There is significant understanding ofthe relations between the molecular events and their phenomenological manifestations in the activation of muscle contraction by calcium ion (1-4). Yet this understanding is not complete. Much of it is based on concepts from the theory of equilibrium systems and from other limiting cases, whereas contraction and its activation are distinctly nonequilibrium phenomena, even at the stationary state, and the limiting cases are so particular that they would not seem to obtain in muscle. We have recently begun to develop a model of cooperative systems with nonequilibrium stationary states (5), and in this paper we use this model to offer insights into these facets of the Ca2" activation process. We will attempt to show that some of the previous interpretations of this process have been based on untenable assumptions. We will also offer explanations for some puzzling aspects ofthe phenomenon, but we will not attempt to develop a complete quantitative model; our goal is qualitative rather then quantitative. We will consider only essential aspects of the phenomenon so that the model reflects its basic features. (Derivations of the approximations and details of other points are available upon request.) The model should thus be considered a paradigm for more accurate models. THE MODELWe picture the thin filament as a lattice of two classes of sites: those on troponin that adsorb Ca2" and the actins. Contraction is brought about by a cyclic reaction of projections of myosin from the thick filament, the crossbridges, with the actins and is powered by an ATPase located on the myosins (1-4). It is generally acknowledged that a crossbridge may exist in various states, both when it is reacting with an actin and when it is not reacting. However, because we are concerned with the activation of contraction, not the contraction itself, a two-state cros...

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Section: The Modelmentioning

confidence: 69%

Section: The Modelmentioning

confidence: 72%

Section: The Modelmentioning

confidence: 99%

See 1 more Smart Citation

Activation of thin-filament-regulated muscle by calcium ion: considerations based on nearest-neighbor lattice statistics.

Shiner¹,

Solaro

1982

Proc. Natl. Acad. Sci. U.S.A.

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“…Although Pi decreases the maximum force, it accelerates muscle kinetics, as judged by the redevelopment of tension after a quick stretch (Herzig & Riuegg, 1977;Herzig et al 1981) and the relaxation from rigor tension after the liberation of caged ATP (Hibberd, Dantzig, Trentham & Goldman, 1985). However, Pi does not affect the maximum speed of unloaded shortening (Johnston & Altringham, 1985).…”

Section: Influence Of Pi On the Force-[ca2+] Relationshipmentioning

confidence: 99%

“…However, Pi does not affect the maximum speed of unloaded shortening (Johnston & Altringham, 1985). Possible mechanisms for some of the actions of Pi have been considered previously (White, 1973;Herzig et al 1981;Brandt et al 1982). The results in the present paper can be 598 Pi AND CREATINE PHOSPHATE ON SKINNED MUSCLE explained with reference to a scheme in which the release of P1 from the actomyosinproducts complex occurs at a step which is close to equilibrium and which precedes ADP release (Lymn & Taylor, 1971;Taylor, 1979;Eisenberg & Greene, 1980;Sleep & Hutton, 1980 Reaction 1 may be readily reversible whereas reaction 2, which is not readily reversible (Sleep & Hutton, 1980) may be linked to the generation offorce (see Huxley, 1980).…”

Section: Influence Of Pi On the Force-[ca2+] Relationshipmentioning

confidence: 99%

The effects of inorganic phosphate and creatine phosphate on force production in skinned muscles from rat ventricle.

Kentish¹

1986

The Journal of Physiology

333

186

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SUMMARY1. Thin ventricular trabeculae from rat hearts were skinned with the non-ionic detergent Triton X-100. The isometric force development of these muscles was investigated over a range of Ca2+ concentrations (0-2-200 gM) in the presence of various concentrations of creatine phosphate (CP), creatine and inorganic phosphate (Pi). Creatine (0-30 mM) was without effect on the skinned muscles.5. The inhibitory effects of Pi suggest that a net hydrolysis of CP to Pi and creatine in the myoplasm of intact cardiac cells could reduce force development at a given myoplasmic [Ca2+], especially if the latter was below the level needed to fully activate the myofibrils. This suggestion is discussed in relation to the CP hydrolysis and decrease in force development that are observed in cardiac muscle during hypoxia or ischaemia.

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Metabolism and Energetics of Vascular Smooth Muscle

Peterson¹,

Rutgeerts²

1989

Physiology and Pathophysiology of the Heart

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Vanadare and phosphate ions reduce tension and increase cross-bridge kinetics in chemically skinned heart muscle

Cited by 75 publications

References 14 publications

Activation of thin-filament-regulated muscle by calcium ion: considerations based on nearest-neighbor lattice statistics.

Activation of thin-filament-regulated muscle by calcium ion: considerations based on nearest-neighbor lattice statistics.

The effects of inorganic phosphate and creatine phosphate on force production in skinned muscles from rat ventricle.

Metabolism and Energetics of Vascular Smooth Muscle

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