Contractile proteins in globally “stunned” rabbit myocardium

Andres, Janusz; Moczarska, A; Stȩpkowski, Dariusz; Kakol, I

doi:10.1007/bf02190601

Cited by 15 publications

(11 citation statements)

References 26 publications

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“…In a study of dog hearts, Toyo-Oka and Ross 10 reported a loss of TnI from myofibrils isolated from myocardial tissue made ischemic in situ. A loss of TnI was also suggested by the results of Andres et al, 40 on the basis of the response to isoproterenol of isolated rat hearts that experienced 20 minutes of ischemia followed by reperfusion. These myofibrils demonstrated an increase in Ca 2ϩ sensitivity compared with preparations from control hearts.…”

Section: Changes In Myofilament Proteins Induced By Ischemia/reperfusionmentioning

confidence: 61%

Breakdown and Release of Myofilament Proteins During Ischemia and Ischemia/Reperfusion in Rat Hearts

Eyk

Powers²,

Law³

et al. 1998

Circulation Research

212

156

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Abstract-Our objective in experiments reported here was to identify myofilament proteins of rat hearts either lost or degraded by cardiac ischemia (15-or 60-minute duration) with and without 45 minutes of reperfusion. We correlated these changes with alterations in myofilament sensitivity to Ca 2ϩ and maximum force generation. Protein degradation and loss were assessed by high-performance liquid chromatography, SDS-PAGE, Western blotting analysis, and amino acid sequencing. Compared with nonischemic control hearts, bundles of skinned fibers from hearts subjected to ischemia alone demonstrated a decrease in maximum force generation and an increase in sensitivity to Ca 2ϩ . These changes in function were increased with the duration of the ischemia and with reperfusion. With increasing duration of ischemia, there was an increased loss and degradation of myofibrillar ␣-actinin and troponin I (TnI) at its C-terminus. ␣-Actinin and TnI were most susceptible to ischemia, but with 60 minutes of ischemia/reperfusion, there was also degradation of myosin light chain-1 (MLC1) involving a clip of residues 1 to 19. The MLC1 degradation product was detected in the reperfusion effluent (along with troponin T, tropomyosin, and ␣-actinin) but not in the tissue with 60 minutes of ischemia with no reperfusion. Moreover, with ischemia the following proteins became associated with the myofibrils: GAPDH and proteins of the mitochondrial ATP synthase complex. Our results provide new evidence regarding the mechanism by which ischemia/reperfusion causes myocardial injury and support the hypothesis that an important element in the injury is altered activity and structure of the myofilaments. (Circ Res. 1998;82:261-271.)

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Section: Changes In Myofilament Proteins Induced By Ischemia/reperfusionmentioning

confidence: 61%

Breakdown and Release of Myofilament Proteins During Ischemia and Ischemia/Reperfusion in Rat Hearts

Eyk

Powers²,

Law³

et al. 1998

Circulation Research

212

156

View full text Add to dashboard Cite

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“…Various studies have implicated CTnI as a protein associated with myocardial ischemia/reperfusion-induced injury (57,58). Examination of CTnI degradation showed that the C-terminal region of CTnI could be easily cleaved near amino acid 193 during myocardial stunning, producing a proteolytic fragment of a smaller molecular weight (∼26 kDa vs. 32 kDa of intact CTnI) (59).…”

Section: Troponin Imentioning

confidence: 99%

The Role of Troponins in Muscle Contraction

2002

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SummaryTroponin (Tn) is the sarcomeric Ca 2+ regulator for striated (skeletal and cardiac) muscle contraction. On binding Ca 2+ Tn transmits information via structural changes throughout the actintropomyosin filaments, activating myosin ATPase activity and muscle contraction. Although the Tn-mediated regulation of striated muscle contraction is now well understood, the role of different Tn isoforms in these processes is the subject of intensive investigations. This review addresses the physiological significance of the multiple Tn isoforms in skeletal and cardiac muscles as well as their role in the regulation of contraction.

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“…However, Andres et al observed that the Ca 2+ responsiveness of isolated myofibrils from globally stunned rabbit myocardium shifted to higher Ca 2+ concentrations, i.e. a decrease in Ca 2+ sensitivity [41]. Fig.…”

Section: Discussionmentioning

confidence: 96%

“…Furthermore, the latter investigators explored the possibility that altered phosphorylation degree of TnI or myosin-lightchains causes the observed Ca 2+ desensitization of the myofibrils, but could not find any changes in phosphorylation [41]. These controversial findings [18,41] led us to examine these aspects in post-ischemic myocardium obtained from anesthetized open-chest pigs.…”

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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Contractile proteins in globally “stunned” rabbit myocardium

Cited by 15 publications

References 26 publications

Breakdown and Release of Myofilament Proteins During Ischemia and Ischemia/Reperfusion in Rat Hearts

Breakdown and Release of Myofilament Proteins During Ischemia and Ischemia/Reperfusion in Rat Hearts

The Role of Troponins in Muscle Contraction

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