Protein synthesis and degradation in cardiac stress.

Schreiber, Sidney S.; Evans, Carole; Oratz, Murray; Rothschild, Marcus A.

doi:10.1161/01.res.48.5.601

Cited by 62 publications

(26 citation statements)

References 106 publications

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“…These results strongly support the concept that thyroxine-induced cardiac hypertrophy is mediated by changes in cardiac output and cardiac work. This data is similar to that obtained in myocyte cell culture (17), in vivo in rats treated simultaneously with T4 and propranolol (Klein, I., manuscript submitted for publication), and in cats with differential cardiac muscle loading (20), and supports the concept that cardiac work per se is an important mediator of myocardial protein synthesis (6,7,17).…”

Section: Discussionsupporting

confidence: 83%

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Effects of thyroid hormone on cardiac size and myosin content of the heterotopically transplanted rat heart.

Klein¹,

Hong²

1986

J. Clin. Invest.

165

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Infrarenal heterotopic cardiac isografts maintain structural and functional integrity. We have used this transplantation model to further explore the mechanisms of thyroid hormone-induced cardiac hypertrophy. Thyroid hormone administration, 1-thyroxine (T4) 10 Mg/animal per d, led to a significant 30% increase in total heart weight and a 40% increase in the myosin content of the in situ heart when compared with control. In contrast, T4 treatment was without effect on the heart weight, protein content, rate of protein synthesis, or calculated myosin content of the heterotopic, nonworking heart. Heterotopic hearts demonstrated a significant decrease in the percentage of the VI myosin isoenzyme from 95% to 61%. This shift occurred in euthyroid animals but was prevented by T4 treatment. These results suggest that thyroxine-induced cardiac hypertrophy is mediated indirectly via changes in cardiac work. Myosin isoenzyme expression can be altered by changes in work load but is still responsive to increased levels of thyroid hormone.

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Section: Discussionsupporting

confidence: 83%

“…These changes in the myocardial protein synthesis occur in association with an increased heart rate, cardiac output, increased myocardial contractility, and the development of cardiac hypertrophy (1,3,6). Thus the hyperthyroid heart performs increased work, a stress similar to that shown by others to produce cardiac hypertrophy (6,7).…”

Section: Introductionmentioning

confidence: 93%

Effects of thyroid hormone on cardiac size and myosin content of the heterotopically transplanted rat heart.

Klein¹,

Hong²

1986

J. Clin. Invest.

165

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“…Until now, analysis of protein synthesis in the overloaded heart has been mainly quantitative and dealt with either total proteins (6,28,29) or the major sarcomeric proteins (30,31). Analysis of the in vivo synthesis of the less abundant proteins was hampered by the low level of their labeling despite the continuous infusion of a radioactive precursor for several hours (6).…”

Section: Discussionmentioning

confidence: 99%

Synthesis of stress proteins in rat cardiac myocytes 2-4 days after imposition of hemodynamic overload.

Delcayre

Samuel²,

Marotte³

et al. 1988

J. Clin. Invest.

109

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Isolated adult myocytes incubated with I35Slmethionine were used to study the expression of proteins in the rat heart during the first 2 wk after either pressure or volume overload. In both models an early (24 d) and transient expression of three major stress proteins (heat shock protein [HSPJ HSP 70, HSP 68, and HSP 58) was observed together with an increased synthesis of putative ribosomal proteins. Only traces of 35S-labeled HSPs were detected in controls and sham-operated animals. The three stress proteins were identified by their migration in two-dimensional gels, by comigration with HSPs, which had been induced in myocytes by incubation at 41°C and immunoblot analysis using antisera directed against the 70-kD protein.Immunohistochemical staining of HSP 70 in rod-shaped myocytes and detection by immunoblot showed that HSP 70 was equally present and distributed in both sham-operated and overloaded hearts, and provided no evidence for a subpopulation of myocytes acutely involved in the increased expression of HSP 70. It is suggested that the transient expression of HSPs that occurs during the early adaptation of the myocardial cells to overload could confer some degree of protection to the actively growing myocytes.

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“…The myocardium is plastic, similar to skeletal muscle, and mechanical loading and other factors can shift the relative isoform abundance of the cardiac motor proteins. Exercise training or, conversely, relative sedentary states can radically alter cardiac muscle mass as well as the expression of MyHC isoforms (Schreiber et al, 1981;Pagani and Solaro, 1983;McDermott et al, 1985;Schaible and Scheuer, 1985; Izumo et al, 1987;Morris et al, 1990;Morgan and Baker, 1991; Klein et al, 1992;Tanamura et al, 1993; Geenen et al, 1994;Wade et al, 1999).…”

Section: Echocardiogram and Myosin Of Hibernatorsmentioning

confidence: 99%

“…Numerous factors control the regulation of these contractile proteins in mammals (Schreiber et al, 1981;Pagani and Solaro, 1983;McDermott et al, 1985;Schaible and Scheuer, 1985;Izumo et al, 1987;Morris et al, 1990;Morgan and Baker, 1991;Klein et al, 1992;Tanamura et al, 1993;Baldwin and Haddad, 2001), and a number of pathologies in the heart are noted (Gupta, 2007). Shifts in the relative expression of isoforms are common, and confer critical changes in the contractile strength and speed of the chamber contraction (Narolska et al, 2005a;Narolska et al, 2005b).…”

Section: Cardiac Myosin Isoform Expression In Ground Squirrelsmentioning

confidence: 99%

Increase in cardiac myosin heavy-chain (MyHC) alpha protein isoform in hibernating ground squirrels, with echocardiographic visualization of ventricular wall hypertrophy and prolonged contraction.

Nelson

Rourke

2013

Journal of Experimental Biology

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SUMMARYDeep hibernators such as golden-mantled ground squirrels (Callospermophilus lateralis) have multiple challenges to cardiac function during low temperature torpor and subsequent arousals. As heart rates fall from over 300 beats min -1 to less than 10, chamber dilation and reduced cardiac output could lead to congestive myopathy. We performed echocardiography on a cohort of individuals prior to and after several months of hibernation. The left ventricular chamber exhibited eccentric and concentric hypertrophy during hibernation and thus calculated ventricular mass was ~30% greater. Ventricular ejection fraction was mildly reduced during hibernation but stroke volumes were greater due to the eccentric hypertrophy and dramatically increased diastolic filling volumes. Globally, the systolic phase in hibernation was ~9.5 times longer, and the diastolic phase was 28× longer. Left atrial ejection generally was not observed during hibernation. Atrial ejection returned weakly during early arousal. Strain echocardiography assessed the velocity and total movement distance of contraction and relaxation for regional ventricular segments in active and early arousal states. Myocardial systolic strain during early arousal was significantly greater than the active state, indicating greater total contractile movement. This mirrored the increased ventricular ejection fraction noted with early arousal. However, strain rates were slower during early arousal than during the active period, particularly systolic strain, which was 33% of active, compared with the rate of diastolic strain, which was 67% of active. As heart rate rose during the arousal period, myocardial velocities and strain rates also increased; this was matched closely by cardiac output. Curiously, though heart rates were only 26% of active heart rates during early arousal, the cardiac output was nearly 40% of the active state, suggesting an efficient pumping system. We further analyzed proportions of cardiac myosin heavy-chain (MyHC) isoforms in a separate cohort of squirrels over 5 months, including time points before hibernation, during hibernation and just prior to emergence. Hibernating individuals were maintained in both a 4°C cold room and a 20°C warm room. Measured by SDS-PAGE, relative percentages of cardiac MyHC alpha were increased during hibernation, at both hibernacula temperatures. A potential increase in contractile speed, and power, from more abundant MyHC alpha may aid force generation at low temperature and at low heart rates. Unlike many models of cardiomyopathies where the alpha isoform is replaced by the beta isoform in order to reduce oxygen consumption, ground squirrels demonstrate a potential cardioprotective mechanism to maintain cardiac output during torpor. Received 25 March 2013; Accepted 4 September 2013Key words: hibernation, MyHC, echocardiogram, atrial contraction, cardiac function. Echocardiogram and myosin of hibernatorsThe myosin heavy-chain isoforms (MyHC) are crucial determinants of contractile performance in cardiac muscle t...

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Protein synthesis and degradation in cardiac stress.

Cited by 62 publications

References 106 publications

Effects of thyroid hormone on cardiac size and myosin content of the heterotopically transplanted rat heart.

Effects of thyroid hormone on cardiac size and myosin content of the heterotopically transplanted rat heart.

Synthesis of stress proteins in rat cardiac myocytes 2-4 days after imposition of hemodynamic overload.

Increase in cardiac myosin heavy-chain (MyHC) alpha protein isoform in hibernating ground squirrels, with echocardiographic visualization of ventricular wall hypertrophy and prolonged contraction.

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