Control of Heat Produced during ATP Hydrolysis by the Sarcoplasmic Reticulum Ca2+-ATPase in the Absence of A Ca2+Gradient

Meis, Leopoldo de

doi:10.1006/bbrc.1997.8028

Cited by 18 publications

(6 citation statements)

References 24 publications

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“…The degree of leakage increased when the heparin concentration was raised to 10 µg/ml and although the vesicles were still able to hydrolyse ATP, they were no longer able to accumulate Ca 2+ . This promoted a decrease in the H cal to the same value as that measured with leaky vesicles (de Meis et al 1997, de Meis 1998a.…”

Section: Heat Production and Atp Synthesissupporting

confidence: 67%

“…Data obtained in our laboratory during the past three years (de Meis et al 1997, de Meis 1998a,b, Mitidieri & de Meis 1999 indicate that heat is produced during the uncoupled Ca 2+ efflux. The coupled and the uncoupled Ca 2+ efflux may represent two distinct routes of energy conversion, both mediated by the Ca 2+ -ATPase in which the osmotic energy derived from the Ca 2+ gradient is either used to synthesize ATP (coupled Ca 2+ efflux) or is dissipated into the medium as heat (uncoupled Ca 2+ efflux).…”

Section: Introductionmentioning

confidence: 94%

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Energy interconversion by the sarcoplasmic reticulum Ca2+-ATPase: ATP hydrolysis, Ca2+ transport, ATP synthesis and heat production

Meis

2000

An. Acad. Bras. Ciênc.

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The sarcoplasmic reticulum of skeletal muscle retains a membrane bound Ca 2+ -ATPase which is able to interconvert different forms of energy. A part of the chemical energy released during ATP hydrolysis is converted into heat and in the bibliography it is assumed that the amount of heat produced during the hydrolysis of an ATP molecule is always the same, as if the energy released during ATP cleavage were divided in two non-interchangeable parts: one would be converted into heat, and the other used for Ca 2+ transport. Data obtained in our laboratory during the past three years indicate that the amount of heat released during the hydrolysis of ATP may vary between 7 and 32 Kcal/mol depending on whether or not a transmembrane Ca 2+ gradient is formed across the sarcoplasmic reticulum membrane. Drugs such as heparin and dimethyl sulfoxide are able to modify the fraction of the chemical energy released during ATP hydrolysis which is used for Ca 2+ transport and the fraction which is dissipated in the surrounding medium as heat.

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Section: Heat Production and Atp Synthesissupporting

confidence: 67%

Section: Introductionmentioning

confidence: 94%

Energy interconversion by the sarcoplasmic reticulum Ca2+-ATPase: ATP hydrolysis, Ca2+ transport, ATP synthesis and heat production

Meis

2000

An. Acad. Bras. Ciênc.

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“…However, SLN could have a function in SR related to the role of muscle in nonshivering thermogenesis [32]. In animals lacking brown adipose tissue, the principle source of heat during non-shivering thermogenesis is the hydrolysis of ATP by the Ca# + -ATPase of skeletal-muscle SR [32,33]. Part of the energy released when ATP is hydrolysed is dissipated as heat and part is used to drive Ca# + across the membrane, against its concentration gradient [33,34].…”

Section: The Physiological Significance Of Slnmentioning

confidence: 99%

Sarcolipin uncouples hydrolysis of ATP from accumulation of Ca2+ by the Ca2+-ATPase of skeletal-muscle sarcoplasmic reticulum

Smith

Broadbridge

East

et al. 2002

Biochemical Journal

116

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Sarcolipin (SLN) is a small peptide found in the sarcoplasmic reticulum of skeletal muscle. It is predicted to contain a single hydrophobic transmembrane α-helix. Fluorescence emission spectra for the single Trp residue of SLN suggest that SLN incorporates fully into bilayers of dioleoylphosphatidylcholine, but only partially into bilayers of phosphatidylcholines with long (C22 or C24) fatty acyl chains. The fluorescence of SLN is quenched in bilayers of dibromostearoylphosphatidylcholine, also consistent with incorporation into the lipid bilayer. SLN was reconstituted with the Ca2+-ATPase of skeletal-muscle sarcoplasmic reticulum. Even at a 50:1 molar ratio of SLN/ATPase, SLN had no significant effect on the rate of ATP hydrolysis by the ATPase or on the Ca2+-dependence of ATP hydrolysis. However, at a molar ratio of SLN/ATPase of 2:1 or higher the presence of SLN resulted in a marked decrease in the level of accumulation of Ca2+ by reconstituted vesicles. The effect of SLN was structurally specific and did not result from a breakdown in the vesicular structure or from the formation of non-specific ion channels. Vesicles were impermeable to Ca2+ in the absence of ATP in the external medium. The effects of SLN on accumulation of Ca2+ can be simulated assuming that SLN increases the rate of slippage on the ATPase and the rate of passive leak of Ca2+ mediated by the ATPase. It is suggested that the presence of SLN could be important in non-shivering thermogenesis, a process in which heat is generated by hydrolysis of ATP by skeletal-muscle sarcoplasmic reticulum.

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“…1 ) [4–6]. However, a number of experimental procedures and conditions have been shown to lead to partial uncoupling of Ca 2+ transport from ATP hydrolysis through changes in the reaction cycle of the SERCA pump [5–13]. For example, passive Ca 2+ efflux by the pump occurs when a high Ca 2+ concentration in the lumen of the SR promotes binding of Ca 2+ to the E2 form of the enzyme, leading to its conversion back to E1 (reactions 7–9, Fig.…”

Section: Introductionmentioning

confidence: 99%

“…1) [6,11,13]. Although the reactions of uncoupled ATP hydrolysis vary, the net result is the same: ultimately most of the energy derived from ATP hydrolysis is converted into heat [5,9,10,12–15].…”

Section: Introductionmentioning

confidence: 99%

Ablation of sarcolipin decreases the energy requirements for Ca²⁺ transport by sarco(endo)plasmic reticulum Ca²⁺‐ATPases in resting skeletal muscle

et al. 2013

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a b s t r a c tThe purpose of this study was to examine the effects of sarcolipin (SLN) on sarco(endo) plasmic reticulum Ca 2+ -ATPase (SERCA pump) energetics in vivo and resting skeletal muscle metabolic rate. Using SLN knockout (Sln À/À ) mice we show that SLN ablation increases the transport stoichiometry of SERCA pumps (Ca 2+ uptake/Ca 2+ -ATPase activity) and decreases the relative contribution of SERCA pumps to resting oxygen consumption (VO 2 ) in soleus without affecting soleus or whole body VO 2 . These data suggest that the lower energy requirements for Ca 2+ cycling in resting skeletal muscle of Sln À/À mice do not impact significantly either skeletal muscle or whole body metabolic rate.

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Control of Heat Produced during ATP Hydrolysis by the Sarcoplasmic Reticulum Ca2+-ATPase in the Absence of A Ca2+Gradient

Cited by 18 publications

References 24 publications

Energy interconversion by the sarcoplasmic reticulum Ca2+-ATPase: ATP hydrolysis, Ca2+ transport, ATP synthesis and heat production

Energy interconversion by the sarcoplasmic reticulum Ca2+-ATPase: ATP hydrolysis, Ca2+ transport, ATP synthesis and heat production

Sarcolipin uncouples hydrolysis of ATP from accumulation of Ca2+ by the Ca2+-ATPase of skeletal-muscle sarcoplasmic reticulum

Ablation of sarcolipin decreases the energy requirements for Ca²⁺ transport by sarco(endo)plasmic reticulum Ca²⁺‐ATPases in resting skeletal muscle

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Control of Heat Produced during ATP Hydrolysis by the Sarcoplasmic Reticulum Ca2+-ATPase in the Absence of A Ca2+Gradient

Cited by 18 publications

References 24 publications

Energy interconversion by the sarcoplasmic reticulum Ca2+-ATPase: ATP hydrolysis, Ca2+ transport, ATP synthesis and heat production

Energy interconversion by the sarcoplasmic reticulum Ca2+-ATPase: ATP hydrolysis, Ca2+ transport, ATP synthesis and heat production

Sarcolipin uncouples hydrolysis of ATP from accumulation of Ca2+ by the Ca2+-ATPase of skeletal-muscle sarcoplasmic reticulum

Ablation of sarcolipin decreases the energy requirements for Ca2+ transport by sarco(endo)plasmic reticulum Ca2+‐ATPases in resting skeletal muscle

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Ablation of sarcolipin decreases the energy requirements for Ca²⁺ transport by sarco(endo)plasmic reticulum Ca²⁺‐ATPases in resting skeletal muscle