ATPase activity and force production in myofibrils and twitch characteristics in intact muscle from neonatal, adult, and senescent rat myocardium

Bhatnagar, Gopal M.; Walford, Gary; Beard, Elsie S.; Humphreys, Susie; Lakatta, Edward G.

doi:10.1016/s0022-2828(84)80587-8

Cited by 58 publications

(20 citation statements)

References 41 publications

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“…5 B) do not markedly differ among age groups. Prior study in skinned fibers indicates that in the absence of P3AR stimulation the steady state force-Ca2" relationship does not vary with age (34).…”

Section: Discussionmentioning

confidence: 93%

Age-associated changes in beta-adrenergic modulation on rat cardiac excitation-contraction coupling.

Xiao¹,

Spurgeon²,

O'Connor³

et al. 1994

J. Clin. Invest.

111

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Previous studies have demonstrated that the ability of (.-adrenergic receptor (.BAR) stimulation to increase cardiac contractility declines with aging. In the present study, the control mechanisms of excitation-contraction (EC) to NE were proportional to the reductions in the Ic response. These findings suggest that the observed age-associated reduction in fAR modulation of the cardiac contraction is, in part at least, due to a deficit in modulation of Ca?+, particularly the activity of L-type calcium channels.(J. Clin. Invest. 1994. 94:2051-2059

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Section: Discussionmentioning

confidence: 93%

Age-associated changes in beta-adrenergic modulation on rat cardiac excitation-contraction coupling.

Xiao¹,

Spurgeon²,

O'Connor³

et al. 1994

J. Clin. Invest.

111

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“…Most of the latter studies used intact ventricular preparations, skinned cardiac muscles or isolated cardiomyocytes but only a few used isolated myofibrillar preparations. It is well known that the activity of the actomyosin Ca 2+ stimulated Mg 2+ -ATPase correlates directly with Ca 2+ stimulated tension development in skinned cardiac fibers [40]. Krause was the first to show that the Ca 2+ dependency of ATP hydrolysis of myofibrils isolated from stunned rabbit heart remained unchanged and found that the maximal rate of myofibrillar ATP hydrolysis was also not affected [18].…”

Section: Discussionmentioning

confidence: 99%

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Bezstarosti

Soei

Verdouw

et al. 1997

Molecular and Cellular Biochemistry

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Previously we showed in an in situ porcine model that the thiadiazinone derivative [+]EMD 60263, a Ca 2+ sensitizer without phosphodiesterase III inhibitory properties, increased contractility more profoundly in stunned than in non-stunned myocardium. This finding was consistent with the observed leftward shifts of the pCa 2+ /Mg 2+ -ATPase curves of isolated myofibrils induced by [+]EMD 60263. The aim of the present investigation was to study the possible involvement of protein kinase C in the mechanism of reduced Ca 2+ responsiveness of myofilaments during stunning. No differences were observed in the maximal activity of the Ca 2+ -stimulated Mg 2+ -ATPase and in the pCa 50 of myofibrils isolated from non-stunned and stunned myocardium. After phosphorylation with [gamma-32 P]-ATP and excess of purified rat brain protein kinase C, the myofibrils were separated on sodiumdodecylsulphate-polyacrylamide gelectrophoresis and the 32 P incorporation counted by the Molecular Imager. Ca 2+ / phosphatidylserine/sn-1,2 diolein-dependent 32 P incorporation catalyzed by excess of purified rat brain protein kinase C in C-protein, TnT and TnI subunits did not show any differences between myofibrils from non-stunned and stunned myocardium. However, protein kinase C-induced phosphorylation of myofibrils isolated from ventricular myocardium of sham-operated pigs resulted in a marked leftward shift of the pCa 50 from 6.03 ± 0.04 to 6.44 ± 0.06 (p < 0.05), while porcine heart cyclic AMP-dependent protein kinase-induced phosphorylation resulted in an expected small rightward shift to 5.97, although statistical significance was not reached. Protein kinase C-induced phosphorylation also stimulated (80%) the maximal myofibrillar Mg 2+ -ATPase activity.[+]EMD 60263 (3 µM) produced a leftward shift of the myofibrillar pCa 2+ /Mg 2+ -ATPase curve which was unaffected by prior protein kinase C-induced phosphorylation. In conclusion, the findings with isolated myofibrils from myocardium of anaesthetized open-chest pigs indicate that protein kinase C might be involved in the mechanism of reduced Ca 2+ responsiveness of myofilaments in stunned myocardium. However, at this stage no differences could be found between the maximal activity of the Ca 2+ -stimulated Mg 2+ -ATPase, the pCa 50 and the degree of phosphorylation of myofibrils isolated from stunned and non-stunned myocardium. (Mol Cell Biochem 176: 211-218, 1997) Key words: cardiac myofibrils, cardiac sarcoplasmic reticulum, human, pig, Ca 2+ stimulated Mg 2+ -ATPase, thiadiazinone derivatives, stunningAbbreviations: ATPase -Adenosine-5′-triphosphatase; EGTA -ethylene glycol bis(β-aminoethylether) N,N,N′,N′-tetraacetic acid; DTT -dithiothreitol; MOPS -4-morpholino-propane sulfonic acid; P i -inorganic phosphate; PS -phosphatidylserine; DG -sn-1,2 diolein; SDS-PAAGE -sodiumdodecylsulphate-polyacrylamide gelectrophoresis; PMSF -phenylmethanesulfonylfluoride; PDE III -phosphodiesterase III; LADCA -left anterior descending coronary artery; LCXCA -left circumflex coronary artery; Tn...

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“…Both cross bridge kinetics and activation decay seem to vary during maturation and aging. An age dependent reduction of shortening velocity and in actomyosin or myofibrillar ATPase activity has been described (1,2,5,7,15). This suggests that cross bridge attachment rate slows during aging.…”

Section: Introductionmentioning

confidence: 98%

Age-dependent changes of relaxation and its load sensitivity in rat cardiac muscle

et al. 1988

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The relaxation phase and its load dependence were studied in papillary muscles isolated from the left ventricle of rats of the following ages: 20 days, 2, 8, 18, and 24 months. The myofibrillar ATPase activity and the force-velocity relation were determined in each age group in order to characterize the kinetic properties of the contractile material. Both shortening velocity and myofibrillar ATPase activity showed a progressive reduction with maturation and aging. This observation suggested an age-dependent decrease in cross bridge formation rate. The relaxation phase was characterized by its duration and the maximum rate of tension decline in isometric conditions, and by the speed of relengthening in isotonic conditions. Relaxation became faster and of shorter duration with maturation from 20 days to 2 months and then became slower and of longer duration with further maturation and aging. The sensitivity of relaxation to changes in length or load was evaluated by measuring how much earlier tension declined in the presence of a given length change. An increase in load sensitivity of relaxation was observed during maturation from 20 days to 8 months. This increase was followed by a reduction during aging from 8 to 24 months. Such a biphasic trend of the age-related changes in load sensitivity of relaxation could result from the interplay between the progressive decrease in cross bridge formation rate and a reduction in activation decay rate. The latter was suggested by the prolongation of the relaxation phase and by the maintenance of developed tension during aging.

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ATPase activity and force production in myofibrils and twitch characteristics in intact muscle from neonatal, adult, and senescent rat myocardium

Cited by 58 publications

References 41 publications

Age-associated changes in beta-adrenergic modulation on rat cardiac excitation-contraction coupling.

Age-associated changes in beta-adrenergic modulation on rat cardiac excitation-contraction coupling.

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Age-dependent changes of relaxation and its load sensitivity in rat cardiac muscle

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