scholarly journals Changes in actomyosin ATP consumption rate in rat diaphragm muscle fibers during postnatal development

2003 ◽  
Vol 94 (5) ◽  
pp. 1896-1902 ◽  
Author(s):  
Gary C. Sieck ◽  
Y. S. Prakash ◽  
Young-Soo Han ◽  
Yun-Hua Fang ◽  
Paige C. Geiger ◽  
...  
Keyword(s):  
Postnatal Development ◽  
Consumption Rate ◽  
Rank Order ◽  
Maximum Velocity ◽  
Diaphragm Muscle ◽  
Reserve Capacity ◽  
Rat Diaphragm ◽  
Early Postnatal Development ◽  
Atpase Reaction ◽  
Isoform Expression

Early postnatal development of rat diaphragm muscle (Diam) is marked by dramatic transitions in myosin heavy chain (MHC) isoform expression. We hypothesized that the transition from the neonatal isoform of MHC (MHCNeo) to adult fast MHC isoform expression in Diam fibers is accompanied by an increase in both the maximum velocity of the actomyosin ATPase reaction ( V max ATPase) and the ATP consumption rate during maximum isometric activation (ATPiso). Rat Diam fibers were evaluated at postnatal days 0, 14, and 28 and in adults ( day 84). Across all ages, V max ATPase of fibers was significantly higher than ATPiso. The reserve capacity for ATP consumption [1 − (ratio of ATPiso to V max ATPase)] was remarkably constant (∼55–60%) across age groups, although at day 28 and in adults the reserve capacity for ATP consumption was slightly higher for fibers expressing MHCSlow compared with fast MHC isoforms. At day 28 and in adults, both V max ATPase and ATPiso were lower in fibers expressing MHCSlow followed in rank order by fibers expressing MHC2A, MHC2X, and MHC2B. For fibers expressing MHCNeo, V maxATPase, and ATPiso were comparable to values for adult fibers expressing MHCSlow but significantly lower than values for fibers expressing fast MHC isoforms. We conclude that postnatal transitions from MHCNeo to adult fast MHC isoform expression in Diam fibers are associated with corresponding but disproportionate changes in V max ATPase and ATPiso.

scholarly journals Developmental effects on myonuclear domain size of rat diaphragm fibers

2008 ◽  
Vol 104 (3) ◽  
pp. 787-794 ◽  
Author(s):  
Carlos B. Mantilla ◽  
Rowan V. Sill ◽  
Bharathi Aravamudan ◽  
Wen-Zhi Zhan ◽  
Gary C. Sieck
Keyword(s):  
Postnatal Development ◽  
Domain Size ◽  
Diaphragm Muscle ◽  
Fiber Types ◽  
Rat Diaphragm ◽  
Cross Sectional ◽  
Early Postnatal Development ◽  
Fiber Growth ◽  
Myonuclear Domain ◽  
Isoform Expression

During early postnatal development in rat diaphragm muscle (Diam), significant fiber growth and transitions in myosin heavy chain (MHC) isoform expression occur. Similar to other skeletal muscles, Diam fibers are multinucleated, and each myonucleus regulates the gene products within a finite volume: the myonuclear domain (MND). We hypothesized that postnatal changes in fiber cross-sectional area (CSA) are associated with increased number of myonuclei so that the MND size is maintained. The Diam was removed at postnatal days 14 (P-14) and 28 (P-28). MHC isoform expression was determined by SDS-PAGE. Fiber CSA, myonuclear number, and MND size were measured using confocal microscopy. By P-14, significant coexpression of MHC isoforms was present with no fiber displaying singular expression of MHCNeo. By P-28, singular expression was predominant. MND size was not different across fiber types at P-14. Significant fiber growth was evident by P-28 at all fiber types (fiber CSA increased by 61, 93, and 147% at fibers expressing MHCSlow, MHC2A, and MHC2X, respectively). The number of myonuclei per unit of fiber length was similar across fibers at P-14, but it was greater at fibers expressing MHC2X at P-28. The total number of myonuclei per fiber also increased between P-14 and P-28 at all fiber types. Accordingly, MND size increased significantly by P-28 at all fiber types, and it became larger at fibers expressing MHC2X compared with fibers expressing MHCSlow or MHC2A. These results suggest that MND size is not maintained during the considerable fiber growth associated with postnatal development of the Diam.

Effect of denervation on ATP consumption rate of diaphragm muscle fibers

2007 ◽  
Vol 103 (3) ◽  
pp. 858-866 ◽  
Author(s):  
Gary C. Sieck ◽  
Wen-Zhi Zhan ◽  
Young-Soo Han ◽  
Y. S. Prakash
Keyword(s):  
Consumption Rate ◽  
Atp Hydrolysis ◽  
Maximum Velocity ◽  
Diaphragm Muscle ◽  
Single Type ◽  
Shortening Velocity ◽  
Cycling Rate ◽  
Cross Bridge ◽  
Atpase Reaction ◽  
The Difference

Denervation (DNV) of rat diaphragm muscle (DIAm) decreases myosin heavy chain (MHC) content in fibers expressing MHC2X isoform but not in fibers expressing MHCslow and MHC2A. Since MHC is the site of ATP hydrolysis during muscle contraction, we hypothesized that ATP consumption rate during maximum isometric activation (ATPiso) is reduced following unilateral DIAm DNV and that this effect is most pronounced in fibers expressing MHC2X. In single-type-identified, permeabilized DIAm fibers, ATPiso was measured using NADH-linked fluorometry. The maximum velocity of the actomyosin ATPase reaction ( Vmax ATPase) was determined using quantitative histochemistry. The effect of DNV on maximum unloaded shortening velocity ( Vo) and cross-bridge cycling rate [estimated from the rate constant for force redevelopment ( kTR) following quick release and restretch] was also examined. Two weeks after DNV, ATPiso was significantly reduced in fibers expressing MHC2X, but unaffected in fibers expressing MHCslow and MHC2A. This effect of DNV on fibers expressing MHC2X persisted even after normalization for DNV-induced reduction in MHC content. With DNV, Vo and kTR were slowed in fibers expressing MHC2X, consistent with the effect on ATPiso. The difference between Vmax ATPase and ATPiso reflects reserve capacity for ATP consumption, which was reduced across all fibers following DNV; however, this effect was most pronounced in fibers expressing MHC2X. DNV-induced reductions in ATPiso and Vmax ATPase of fibers expressing MHC2X reflect the underlying decrease in MHC content, while reduction in ATPiso also reflects a slowing of cross-bridge cycling rate.

scholarly journals Selected Contribution: Mechanisms underlying increased force generation by rat diaphragm muscle fibers during development

2001 ◽  
Vol 90 (1) ◽  
pp. 380-388 ◽  
Author(s):  
Paige C. Geiger ◽  
Mark J. Cody ◽  
Rebecca L. Macken ◽  
Megan E. Bayrd ◽  
Yun-Hua Fang ◽  
...  
Keyword(s):  
Postnatal Development ◽  
Developmental Change ◽  
Diaphragm Muscle ◽  
Rat Diaphragm ◽  
Cross Sectional ◽  
Early Postnatal Development ◽  
Standard Curve ◽  
Cross Bridge ◽  
Sds Page ◽  
Cross Bridges

It has been found that maximum specific force (Fmax; force per cross-sectional area) of rat diaphragm muscle doubles from birth to 84 days (adult). We hypothesize that this developmental change in Fmax reflects an increase in myosin heavy chain (MHC) content per half-sarcomere (an estimate of the number of cross bridges in parallel) and/or a greater force per cross bridge in fibers expressing fast MHC isoforms compared with slow and neonatal MHC isoforms (MHCslow and MHCneo, respectively). Single Triton 100-X-permeabilized fibers were activated at a pCa of 4.0. MHC isoform expression was determined by SDS-PAGE. MHC content per half-sarcomere was determined by densitometric analysis and comparison to a standard curve of known MHC concentrations. MHC content per half-sarcomere progressively increased during early postnatal development. When normalized for MHC content per half-sarcomere, fibers expressing MHCslow and coexpressing MHCneoproduced less force than fibers expressing fast MHC isoforms. We conclude that lower force per cross bridge in fibers expressing MHCslow and MHCneo contributes to the lower Fmax seen in early postnatal development.

Postnatal expression of myosin isoforms in an expiratory muscle--external abdominal oblique

1992 ◽  
Vol 73 (5) ◽  
pp. 1860-1866 ◽  
Author(s):  
J. F. Watchko ◽  
M. J. Daood ◽  
R. L. Vazquez ◽  
B. S. Brozanski ◽  
W. A. LaFramboise ◽  
...  
Keyword(s):  
Postnatal Development ◽  
Heavy Chain ◽  
Temporal Patterns ◽  
Abdominal Muscle ◽  
Myosin Isoforms ◽  
Early Postnatal Development ◽  
Expiratory Muscle ◽  
Fast Myosin ◽  
Isoform Expression

We studied the postnatal expression of heavy-chain (MHC) and native myosin isoforms in an expiratory abdominal muscle of the rat, the external abdominal oblique (EO). Moreover, we contrasted EO myosin expression with that of the costal diaphragm (DIA) to draw inspiratory vs. expiratory muscle comparisons during development. Examination of MHC gels demonstrated a mature phenotype of slow and adult fast myosin isoforms at an earlier age in the EO (day 60) than in the DIA [day > 115 (adult)]. The mature MHC phenotype of the EO was characterized by a preponderance of MHC 2B, whereas the DIA was characterized by approximately equal portions of MHC slow, MHC 2A, and MHC 2X. During early postnatal development, there was a delay in the expression of MHC 2A in the EO compared with the DIA. However, MHC 2B, expressed later in development in both muscles, was noted in the EO before the DIA. We conclude that 1) the EO mature myosin phenotype is characterized by a preponderance of fast myosin isoforms and 2) the EO and DIA muscles are subject to different temporal patterns of isoform expression during postnatal development.

Isotonic contractile and fatigue properties of developing rat diaphragm muscle

1998 ◽  
Vol 84 (4) ◽  
pp. 1260-1268 ◽  
Author(s):  
Wen-Zhi Zhan ◽  
Jon F. Watchko ◽  
Y. S. Prakash ◽  
Gary C. Sieck
Keyword(s):  
Power Output ◽  
Supply And Demand ◽  
Maximum Power ◽  
Diaphragm Muscle ◽  
Fatigue Properties ◽  
Rat Diaphragm ◽  
Shortening Velocity ◽  
Endurance Time ◽  
Early Postnatal Development ◽  
Maximum Power Output

Postnatal transitions in myosin heavy chain (MHC) isoform expression were found to be associated with changes in both isometric and isotonic contractile properties of rat diaphragm muscle (Diam). Expression of MHCneo predominated in neonatal Diam fibers but was usually coexpressed with MHCslow or MHC2A isoforms. Expression of MHCneo disappeared by day 28. Expression of MHC2X and MHC2B emerged at day 14 and increased thereafter. Associated with these MHC transitions in the Diam, maximum isometric tetanic force (Po), maximum shortening velocity, and maximum power output progressively increased during early postnatal development. Maximum power output of the Diam occurred at ∼40% Po at days 0 and 7 and at ∼30% Po in older animals. Susceptibility to isometric and isotonic fatigue, defined as a decline in force and power output during repetitive activation, respectively, increased with maturation. Isotonic endurance time, defined as the time for maximum power output to decline to zero, progressively decreased with maturation. In contrast, isometric endurance time, defined as the time for force to decline to 30–40% Po, remained >300 s until after day 28. We speculate that with the postnatal transition to MHC2X and MHC2Bexpression energy requirements for contraction increase, especially during isotonic shortening, leading to a greater imbalance between energy supply and demand.

ATP consumption rate per cross bridge depends on myosin heavy chain isoform

2003 ◽  
Vol 94 (6) ◽  
pp. 2188-2196 ◽  
Author(s):  
Young-Soo Han ◽  
Paige C. Geiger ◽  
Mark J. Cody ◽  
Rebecca L. Macken ◽  
Gary C. Sieck
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Consumption Rate ◽  
Diaphragm Muscle ◽  
Rat Diaphragm ◽  
Myosin Heavy Chain Isoform ◽  
Standard Curve ◽  
Cross Bridge ◽  
Sds Page ◽  
Triton X

In the present study, we tested the hypothesis that intrinsic differences in ATP consumption rate per cross bridge exist across rat diaphragm muscle (Diam) fibers expressing different myosin heavy chain (MHC) isoforms. During maximum Ca2+ activation (pCa 4.0) of single, Triton X-permeabilized Diam fibers, isometric ATP consumption rate was determined by using an NADH-linked fluorometric technique. The MHC concentration in single Diam fibers was determined by densitometric analysis of SDS-PAGE gels and comparison to a standard curve of known MHC concentrations. Isometric ATP consumption rate varied across Diam fibers expressing different MHC isoforms, being highest in fibers expressing MHC2X (1.14 ± 0.08 nmol · mm−3 · s−1) and/or MHC2B (1.33 ± 0.08 nmol · mm−3 · s−1), followed by fibers expressing MHC2A (0.77 ± 0.11 nmol · mm−3 · s−1) and MHCSlow (0.46 ± 0.03 nmol · mm−3 · s−1). These differences in ATP consumption rate also persisted when it was normalized for MHC concentration in single Diam fibers. Normalized ATP consumption rate for MHC concentration varied across Diam fibers expressing different MHC isoforms, being highest in fibers expressing MHC2X (2.02 ± 0.19 s−1) and/or MHC2B (2.64 ± 0.15 s−1), followed by fibers expressing MHC2A(1.57 ± 0.16 s−1) and MHCSlow (0.77 ± 0.05 s−1). On the basis of these results, we conclude that there are intrinsic differences in ATP consumption rate per cross bridge in Diam fibers expressing MHC isoforms.

Hypothyroidism alters diaphragm muscle development

1996 ◽  
Vol 81 (5) ◽  
pp. 1965-1972 ◽  
Author(s):  
Gary C. Sieck ◽  
Louise E. Wilson ◽  
Bruce D. Johnson ◽  
Wen-Zhi Zhan
Keyword(s):  
Muscle Development ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Diaphragm Muscle ◽  
Rat Diaphragm ◽  
Shortening Velocity ◽  
Pregnant Rats ◽  
Isoform Expression ◽  
The Impact

Sieck, Gary C., Louise E. Wilson, Bruce D. Johnson, and Wen-Zhi Zhan. Hypothyroidism alters diaphragm muscle development. J. Appl. Physiol. 81(5): 1965–1972, 1996.—The impact of hypothyroidism (Hyp) on myosin heavy chain (MHC) isoform expression, maximum specific force (Po), fatigability, and maximum unloaded shortening velocity ( V o) was determined in the rat diaphragm muscle (Dia) at 0, 7, 14, 21, and 28 days of age. Hyp was induced by treating pregnant rats with 6- n-propyl-2-thiouracil (0.05% in drinking water) beginning at gestational day 10 and was confirmed by reduced plasma levels of 3,5,3′-triiodothyronine and thyroxine. MHC isoforms were separated on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels and analyzed by densitometry. Isometric Po and fatigue resistance of the Dia were measured in vitro at 26°C, and V o was determined at 15°C with the slack test. Compared with control muscles, expression of MHC-slow was higher and expression of adult fast MHC isoforms was lower in Hyp Dia at all ages. The neonatal isoform of MHC continued to be expressed in the Hyp Dia until day 28. At each age, Po and fatigability were reduced and V o was slower in the Hyp Dia. We conclude that Hyp-induced alterations in MHC isoform expression do not fully predict the changes in Dia contractile properties.

scholarly journals Reserve capacity for ATP consumption during isometric contraction in human skeletal muscle fibers

2001 ◽  
Vol 90 (2) ◽  
pp. 657-664 ◽  
Author(s):  
Young-Soo Han ◽  
David N. Proctor ◽  
Paige C. Geiger ◽  
Gary C. Sieck
Keyword(s):  
Fiber Type ◽  
Vastus Lateralis ◽  
Muscle Fibers ◽  
Maximum Velocity ◽  
Reserve Capacity ◽  
Cost Ratio ◽  
Atpase Reaction ◽  
Tension Cost ◽  
Permeabilized Fibers ◽  
Histochemical Procedure

Maximum velocity of the actomyosin ATPase reaction ( V max ATPase) and ATP consumption rate during maximum isometric activation (ATPiso) were determined in human vastus lateralis (VL) muscle fibers expressing different myosin heavy chain (MHC) isoforms. We hypothesized that the reserve capacity for ATP consumption [1 − (ratio of ATPiso to V maxATPase)] varies across VL muscle fibers expressing different MHC isoforms. Biopsies were obtained from 12 subjects (10 men and 2 women; age 21–66 yr). A quantitative histochemical procedure was used to measure V max ATPase. In permeabilized fibers, ATPiso was measured using an NADH-linked fluorometric procedure. The reserve capacity for ATP consumption was lower for fibers coexpressing MHC2X and MHC2A compared with fibers singularly expressing MHC2A and MHCslow (39 vs. 52 and 56%, respectively). Tension cost (ratio of ATPiso to generated force) also varied with fiber type, being highest in fibers coexpressing MHC2X and MHC2A. We conclude that fiber-type differences in the reserve capacity for ATP consumption and tension cost reflect functional differences such as susceptibility to fatigue.

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