Silver ions induce Ca2+release from the SR in vitro by acting on the Ca2+release channel and the Ca2+pump

Tupling, A. Russell; Green, H J

doi:10.1152/japplphysiol.00756.2001

Cited by 51 publications

(63 citation statements)

References 43 publications

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“…We have followed the procedure used by Ruell et al (31), in which AgNO 3 is used as the releasing agent. In recent work, we have found that, unlike 4-chloro-m-cresol, which is specific to the Ca 2ϩ -release channel, AgNO 3 can also act on the Ca 2ϩ -ATPase and can lead to reversal of the pump action (39). Moreover, because Ca 2ϩ release occurs in two phases, training effects may be different between the phases.…”

Section: Discussionmentioning

confidence: 99%

“…Moreover, because Ca 2ϩ release occurs in two phases, training effects may be different between the phases. This study was completed before our examination of the Ca 2ϩ -release kinetics using different releasing agents (39). As such, we have followed the popular practice of using the second phase of Ca 2ϩ release and the releasing agent AgNO 3 .…”

Section: Discussionmentioning

confidence: 99%

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Adaptations in human muscle sarcoplasmic reticulum to prolonged submaximal training

Green

Ballantyne²,

MacDougall³

et al. 2003

Journal of Applied Physiology

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. Adaptations in human muscle sarcoplasmic reticulum to prolonged submaximal training. J Appl Physiol 94: 2034-2042, 2003; 10.1152/japplphysiol.00244.2002.-In this study, we employed single-leg submaximal cycle training, conducted over a 10-wk period, to investigate adaptations in sarcoplasmic reticulum (SR) Ca 2ϩ -regulatory proteins and processes of the vastus lateralis. During the final weeks, the untrained volunteers (age 21.4 Ϯ 0.3 yr; means Ϯ SE, n ϭ 10) were exercising 5 times/wk and for 60 min/session. Analyses were performed on tissue extracted by needle biopsy ϳ4 days after the last training session. Compared with the control leg, the trained leg displayed a 19% reduction (P Ͻ 0.05) in homogenate maximal Ca 2ϩ -ATPase activity (192 Ϯ 11 vs. 156 Ϯ 18 mol ⅐ g protein Ϫ1 ⅐ min Ϫ1 ), a 4.3% increase (P Ͻ 0.05) in pCa 50, defined as the Ca 2ϩ concentration at half-maximal activity (6.01 Ϯ 0.05 vs. 6.26 Ϯ 0.07), and no change in the Hill coefficient (1.75 Ϯ 0.15 vs. 1.76 Ϯ 0.21). Western blot analysis using monoclonal antibodies (7E6 and A52) revealed a 13% lower (P Ͻ 0.05) sarco(endo)plasmic reticulum Ca 2ϩ -ATPase (SERCA) 1 in trained vs. control in the absence of differences in SERCA2a. Training also resulted in an 18% lower (P Ͻ 0.05) SR Ca 2ϩ uptake and a 26% lower (P Ͻ 0.05) Ca 2ϩ release. It is concluded that a downregulation in SR Ca 2ϩ cycling in vastus lateralis occurs with aerobic-based training, which at least in the case of Ca 2ϩ uptake can be explained by reduction in Ca 2ϩ -ATPase activity and SERCA1 protein levels. calcium homeostasis; Ca 2ϩ -ATPase; Ca 2ϩ uptake; Ca 2ϩ release; exercise REGULAR CONTRACTILE ACTIVITY is a potentially potent stimulus for altering the composition, structure, and function of the muscle cell. Nowhere is this more evident than with the chronic low-frequency electrical stimulation (CLFS) model in which contractile activity is characteristically induced for 12-24 h/day over several weeks. Induced patterns of submaximal contractions of this nature typically applied to muscles composed of a predominance of fast-twitch (type II) fibers result in extensive reorganization of both the excitation and contraction processes and the energy metabolic pathways involved in energy supply. Although the magnitude of the adaptations vary, qualitatively similar adaptations appear to occur between species (dog, rat, mouse, rabbit) (29).Despite the fact that the CLFS model has proved invaluable for studying the limits of phenotypic plasticity in skeletal muscle and the factors regulating the expression of a large number of proteins involved in fiber-type transformation, it is nonphysiological (30). In physiological models, voluntary activity is used to elicit training adaptations. Voluntary training typically involves a relatively brief session of exercise followed by a prolonged recovery period, which could last for 2-3 days depending on the training frequency. Moreover, it is not clear how the intracellular signals mediating altered protein expression in CLFS translate into different ...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Adaptations in human muscle sarcoplasmic reticulum to prolonged submaximal training

Green

Ballantyne²,

MacDougall³

et al. 2003

Journal of Applied Physiology

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“…Oxalate-supported SR Ca 2+ uptake rate was assessed in RV muscle homogenates using the fluorescent dye Indo-1 and a spectrofluorometer equipped with dual-emission monochromators and was normalized for total protein concentration (Tupling and Green, 2002). SERCA activity was assessed via an enzymecoupled assay in crude homogenates prepared from RV muscles in the presence (without ionophore A23187) or absence (with 4 mM ionophore A23187) of a Ca 2+ gradient using a spectrophotometric plate reader assay which has been described previously (Duhamel et al, 2007).…”

Section: Serca Ca 2+ Uptake and Ca 2+ -Atpase Activitymentioning

confidence: 99%

Dietary docosahexaenoic acid supplementation reduces SERCA Ca2+ transport efficiency in rat skeletal muscle

Fajardo

Bombardier

Irvine

et al. 2015

Chemistry and Physics of Lipids

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“…Differentiating the linear-fit curves allows determination of Ca 2ϩ release rates. Phase 1 Ca 2ϩ release is characterized by a rapid early release (ϳ0 -2 s), whereas phase 2 Ca 2ϩ release is characterized as the slower, more delayed release (ϳ5-15 s) (13,49).…”

Section: Participantsmentioning

confidence: 99%

Comparative effects of a low-carbohydrate diet and exercise plus a low-carbohydrate diet on muscle sarcoplasmic reticulum responses in males

Duhamel

Green²,

Perco³

et al. 2006

American Journal of Physiology-Cell Physiology

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ployed a glycogen-depleting session of exercise followed by a lowcarbohydrate (CHO) diet to investigate modifications that occur in muscle sarcoplasmic reticulum (SR) Ca 2ϩ -cycling properties compared with low-CHO diet alone. SR properties were assessed in nine untrained males [peak aerobic power (V O2 peak) ϭ 43.6 Ϯ 2.6 (SE) ml ⅐ kg Ϫ1 ⅐ min Ϫ1 ] during prolonged cycle exercise to fatigue performed at ϳ58% V O2 peak after 4 days of low-CHO diet (Lo CHO) and after glycogen-depleting exercise plus 4 days of low-CHO (ExϩLo CHO). Compared with Lo CHO, ExϩLo CHO resulted in 12% lower (P Ͻ 0.05) resting maximal Ca 2ϩ -ATPase activity (Vmax ϭ 174 Ϯ 12 vs. 153 Ϯ 10 mol ⅐ g protein Ϫ1 ⅐ min Ϫ1 ) and smaller reduction in Vmax induced during exercise. A similar effect was observed for Ca 2ϩ uptake. The Hill coefficient, defined as slope of the relationship between cytosolic free Ca 2ϩ concentration and Ca 2ϩ -ATPase activity, was higher (P Ͻ 0.05) at rest (2.07 Ϯ 0.15 vs. 1.90 Ϯ 0.10) with ExϩLo CHO, an effect that persisted throughout the exercise. The coupling ratio, defined as the ratio of Ca 2ϩ uptake to Vmax, was 23-30% elevated (P Ͻ 0.05) at rest and during the first 60 min of exercise with ExϩLo CHO. The ϳ27 and 34% reductions (P Ͻ 0.05) in phase 1 and phase 2 Ca 2ϩ release, respectively, observed during exercise with Lo CHO were not altered by ExϩLo CHO. These results indicate that when prolonged exercise precedes a short-term Lo CHO diet, Ca 2ϩ sequestration properties and efficiency are improved compared with those during Lo CHO alone. calcium cycling; vastus lateralis; contractile activity; glycogen; phosphorylation potential ADEQUATE RESERVES of the endogenous muscle carbohydrate glycogen are recognized as essential for sustaining contractile activity (2,7,20). Intuitively, the most obvious mechanism for this effect would appear to relate to its role as a fuel for oxidative phosphorylation and glycolysis, the metabolic pathways involved in regenerating the ATP necessary to supply the energy needs of the active muscle. According to this theory, the depletion of muscle glycogen would be expected to compromise the flux rate through these metabolic pathways resulting in an energy crisis and an inability to supply the ATP require-

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Silver ions induce Ca²⁺release from the SR in vitro by acting on the Ca²⁺release channel and the Ca²⁺pump

Cited by 51 publications

References 43 publications

Adaptations in human muscle sarcoplasmic reticulum to prolonged submaximal training

Adaptations in human muscle sarcoplasmic reticulum to prolonged submaximal training

Dietary docosahexaenoic acid supplementation reduces SERCA Ca2+ transport efficiency in rat skeletal muscle

Comparative effects of a low-carbohydrate diet and exercise plus a low-carbohydrate diet on muscle sarcoplasmic reticulum responses in males

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