scholarly journals Early Postmortem Metabolism and Protease Activation in Bovine Muscles

2019 ◽  
Vol 3 (2) ◽  
Author(s):  
P. Ramos ◽  
L. Bell ◽  
M. Pedrao ◽  
T. Scheffler
Keyword(s):  
Energy Metabolism ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Interaction Effect ◽  
Fixed Effects ◽  
Caspase 3 ◽  
Block Design ◽  
Lactate Concentration ◽  
Protease Activation ◽  
Early Postmortem

ObjectivesThe conversion of muscle to meat is largely controlled by postmortem energy metabolism and pH decline. These biochemical changes influence activity of enzymes implicated in proteolysis and meat tenderization. Therefore, our objective was to investigate pH decline, muscle energy metabolism, and protease activation in functionally distinct bovine muscles.Materials and MethodsSteers (n = 6) were harvested at approximately 18.5 mo and 630 kg live weight. Samples from the longissimus lumborum (LL) and diaphragm (Dia) were taken at 1, 3, and 24h postmortem, immediately frozen using liquid nitrogen, and stored in ultra-freezer until analysis. Muscle pH was obtained using a pH meter at the same time points. Myosin heavy chain composition (I, IIa, and IIx) was determined using gel electrophoresis. Substrate (residual glycogen), as well as glycolytic metabolites, glucose, glucose-6-phosphate, and lactate, were quantified by enzymatic methods; muscle ATP at 1 and 3h was also determined. Western blotting was used to evaluate protease activation (calpain-1 and caspase-3). Data were analyzed using a randomized block design, with slaughter date as block. Animal within slaughter date was considered as random effect and fixed effects of muscle, time, and the interaction tested. Time was considered a repeated measure.ResultsDiaphragm contained a greater percentage of slow myosin heavy chain compared to LL (80% vs. 12%, respectively). Consistent with fiber type, LL contained greater glycogen than Dia at 1h (P < 0.05), but not at subsequent times postmortem. Overall, a greater decline in glycogen occurred in LL. Accordingly, lactate concentration increased markedly in LL postmortem and to a lesser extent in Dia (interaction effect; P < 0.01). Although muscles exhibited similar lactate content at 1h, at 24h the LL showed elevated lactate relative to Dia (88 vs. 53 µmol/g tissue, respectively). Accumulation of glucose and glucose-6-phosphate were affected by muscle (P < 0.01) and time (P < 0.01), with greater final content in LL compared to Dia. Muscles exhibited different patterns of postmortem pH decline (muscle × time, P < 0.0001). Initially, pH of LL was higher than Dia (P < 0.01) and remained different at 3h (P < 0.05); but by 24h, pH values were similar. Content of ATP was influenced by muscle (P < 0.01) and time (P < 0.01). Initial ATP was greater (P < 0.01) in LL than in Dia and remained greater (P = 0.002) at 3h postmortem. From 1 to 24h, the pattern of calpain autolysis differed between muscles (interaction effect; P = 0.01). Calpain-1 autolysis was similar at all times in Dia, whereas autolysis increased in LL from 3h to 24h postmortem. Caspase-3 was identified by one band (32 kDa) that represents the zymogen (procaspase-3). Procaspase-3 content is affected by muscle (P < 0.01), with Dia containing greater content than LL.ConclusionAlthough the Dia is considered a slow muscle, it exhibited a more rapid pH decline and lower ATP levels than LL early postmortem. These parameters were expected to coincide with more rapid calpain-1 autolysis in Dia, but this was not the case. Further work is necessary to understand the interaction between pH decline, muscle type, and postmortem proteolysis.

Skeletal muscle myosin heavy chain isoforms and energy metabolism after clenbuterol treatment in the rat

2000 ◽  
Vol 279 (3) ◽  
pp. R1076-R1081 ◽  
Author(s):  
P. Rajab ◽  
J. Fox ◽  
S. Riaz ◽  
D. Tomlinson ◽  
D. Ball ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Energy Metabolism ◽  
Myosin Heavy Chain ◽  
Body Mass ◽  
Heavy Chain ◽  
Adenine Nucleotide ◽  
Prolonged Treatment ◽  
Skeletal Muscle Myosin ◽  
Adenine Nucleotide Pool ◽  
Muscle Myosin

Prolonged treatment with the β2-adrenoceptor agonist clenbuterol (1–2 mg · kg body mass−1 · day −1) is known to induce the hypertrophy of fast-contracting fibers and the conversion of slow- to fast-contracting fibers. We investigated the effects of administering a lower dose of clenbuterol (250 μg · kg body mass−1 · day−1) on skeletal muscle myosin heavy chain (MyHC) protein isoform content and adenine nucleotide (ATP, ADP, and AMP) concentrations. Male Wistar rats were administered clenbuterol ( n = 8) or saline ( n = 6) subcutaneously for 8 wk, after which the extensor digitorum longus (EDL) and soleus muscles were removed. We demonstrated an increase of type IIa MyHC protein content in the soleus from ∼0.5% in controls to ∼18% after clenbuterol treatment ( P < 0.05), which was accompanied by an increase in the total adenine nucleotide pool (TAN; ∼19%, P < 0.05) and energy charge [E-C = (ATP + 0.5 ADP)/(ATP + ADP + AMP); ∼4%; P < 0.05]. In the EDL, a reduction in the content of the less prevalent type I MyHC protein from ∼3% in controls to 0% after clenbuterol treatment ( P < 0.05) occurred without any alterations in TAN and E-C. These findings demonstrate that the phenotypic changes previously observed in slow muscle after clenbuterol administration at 1–2 mg · kg body mass−1 · day−1 are also observed at a substantially lower dose and are paralleled by concomitant changes in cellular energy metabolism.

scholarly journals Early postmortem metabolism and protease activation in contrasting bovine muscles

2021 ◽  
Author(s):  
Tracy Scheffler ◽  
Patricia Maloso Ramos ◽  
Lindsey C Bell ◽  
Mayka R. Pedrao
Keyword(s):  
Fixed Effects ◽  
Troponin T ◽  
Fiber Type ◽  
Least Square ◽  
Type I ◽  
Muscle Properties ◽  
Protease Activation ◽  
Bonferroni Test ◽  
Early Postmortem

Muscle to meat conversion is influenced by muscle properties and metabolism. Fiber type profile impacts glycolytic capacity as well as protein turnover rate in vivo. Our objective was to investigate protease content and activation during the early postmortem period using muscles with known divergent metabolism. Samples from longissimus lumborum (LL) and diaphragm (Dia) were taken from predominantly Angus steer carcasses (n = 6) at 1, 3, and 24h postmortem and frozen. Myosin heavy chain (MyHC) isoforms, ATP, glycogen, glucose, glucose-6-phosphate (G6P), and lactate concentrations were determined. Procaspase-3, calpain-1, calpastatin, desmin, and troponin-T were assessed by immunodetection. Fixed effects of muscle (m), time postmortem (t) and the interaction (m × t) were investigated, and least square means were separated by Bonferroni test at 5% significance. Muscles showed contrasting MyHC profiles, with LL represented primarily by IIx and IIa isoforms (~ 88%) whereas Dia contained mostly (80%) type I isoform. Glycogen degradation was more pronounced in LL and coincided with more rapid accumulation of glucose and lactate (P &lt; 0.01). Procaspase-3 content was influenced by muscle (m: P &lt; 0.01), being greater in Dia. Fragments indicating activation of procaspase-3 postmortem were not detected. Calpain-1 autolysis and intact calpastatin (135 kDa) content were influenced by muscle and time (m × t: P &lt; 0.01 and P &lt; 0.01, respectively). Calpastatin fragmentation postmortem was not associated with greater procaspase-3 content. Fast glycolytic LL displayed faster protease activation and greater proteolysis during the first 24h postmortem.&nbsp;

Low-intensity exercise training during doxorubicin treatment protects against cardiotoxicity

2006 ◽  
Vol 100 (2) ◽  
pp. 519-527 ◽  
Author(s):  
Adam J. Chicco ◽  
David S. Hydock ◽  
Carole M. Schneider ◽  
Reid Hayward
Keyword(s):  
Lipid Peroxidation ◽  
Heat Shock ◽  
Exercise Training ◽  
Protein Expression ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Caspase 3 ◽  
Lv Function ◽  
Low Intensity ◽  
Low Intensity Exercise

Doxorubicin (Dox) is a highly effective antineoplastic antibiotic associated with a dose-limiting cardiotoxicity that may result in irreversible cardiomyopathy and heart failure. The purpose of this study was to examine the effects of low-intensity exercise training (LIET) during the course of Dox treatment on cardiac function, myosin heavy chain expression, oxidative stress, and apoptosis activation following treatment. Male Sprague-Dawley rats either remained sedentary or were exercise trained on a motorized treadmill at 15 m/min, 20 min/day, 5 days/wk (Monday through Friday) for 2 wk. During the same 2-wk period, Dox (2.5 mg/kg) or saline was administered intraperitoneally to sedentary and exercised rats 3 days/wk (Monday, Wednesday, Friday) 1–2 h following the exercise training sessions (cumulative Dox dose: 15 mg/kg). Five days following the final injections, hearts were isolated for determination of left ventricular (LV) function, lipid peroxidation, antioxidant enzyme protein expression, 72-kDa heat shock protein expression, caspase-3 activity, and myosin heavy chain isoform expression. Dox treatment significantly impaired LV function and increased caspase-3 activity in sedentary animals ( P < 0.05). LIET attenuated the LV dysfunction and apoptotic signal activation induced by Dox treatment and increased glutathione peroxidase expression, but it had no significant effect on lipid peroxidation, protein expression of myosin heavy chain isoforms, 72-kDa heat shock protein, or superoxide dismutase isoforms. In conclusion, our data suggest that LIET applied during chronic Dox treatment protects against cardiac dysfunction following treatment, possibly by enhancing antioxidant defenses and inhibiting apoptosis.

scholarly journals Myosin heavy chain isoform content and energy metabolism can be uncoupled in pig skeletal muscle

2009 ◽  
Vol 87 (2) ◽  
pp. 522-531 ◽  
Author(s):  
S. K. Park ◽  
A. M. Gunawan ◽  
T. L. Scheffler ◽  
A. L. Grant ◽  
D. E. Gerrard
Keyword(s):  
Skeletal Muscle ◽  
Energy Metabolism ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Myosin Heavy Chain Isoform
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