Mechanisms underlying myosin heavy chain expression during development of the rat diaphragm muscle

2006 ◽  
Vol 101 (6) ◽  
pp. 1546-1555 ◽  
Author(s):  
Paige C. Geiger ◽  
Jeffrey P. Bailey ◽  
Carlos B. Mantilla ◽  
Wen-Zhi Zhan ◽  
Gary C. Sieck
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Diaphragm Muscle ◽  
Rat Diaphragm

Denervation-induced changes in myosin heavy chain expression in the rat diaphragm muscle

2003 ◽  
Vol 95 (2) ◽  
pp. 611-619 ◽  
Author(s):  
Paige C. Geiger ◽  
Jeffrey P. Bailey ◽  
Wen-Zhi Zhan ◽  
Carlos B. Mantilla ◽  
Gary C. Sieck
Keyword(s):  
Protein Expression ◽  
Mrna Expression ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Protein Isoforms ◽  
Diaphragm Muscle ◽  
Northern Analysis ◽  
Mrna Levels ◽  
Rat Diaphragm ◽  
Mrna Isoforms

Unilateral denervation (Dnv) of the rat diaphragm muscle (Diam) markedly alters expression of myosin heavy chain (MHC) isoforms. After 2 wk of Diam Dnv, MHC content per half-sarcomere decreases in fibers expressing MHC2X and MHC2B. We hypothesized that changes in MHC protein expression parallel changes in MHC mRNA expression. Relative MHC isoform mRNA levels were determined by Northern analysis after 1, 3, 7, and 14 days of Dnv of the rat Diam. MHC protein expression was determined by SDS-PAGE. Changes in MHC isoform protein and mRNA expression were not concurrent. Expression of MHCSlow and MHC2X mRNA isoforms decreased dramatically by 3 days of Dnv, whereas that of MHC2A and MHC2B did not change. Expression of all MHC protein isoforms decreased by 3 days of Dnv. We observed a differential effect of rat Diam Dnv on MHC isoform protein and mRNA expression. The time course of the changes in MHC isoform mRNA and protein expression suggests a predominant effect of altered protein turnover rates on MHC protein expression instead of altered transcription after Dnv.

Maximum specific force depends on myosin heavy chain content in rat diaphragm muscle fibers

2000 ◽  
Vol 89 (2) ◽  
pp. 695-703 ◽  
Author(s):  
Paige C. Geiger ◽  
Mark J. Cody ◽  
Rebecca L. Macken ◽  
Gary C. Sieck
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Fiber Type ◽  
Diaphragm Muscle ◽  
Specific Force ◽  
Rat Diaphragm ◽  
Cross Sectional ◽  
High Calcium ◽  
Cross Bridges ◽  
Triton X

In the present study, myosin heavy chain (MHC) content per half sarcomere, an estimate of the number of cross bridges available for force generation, was determined in rat diaphragm muscle (Diam) fibers expressing different MHC isoforms. We hypothesize that fiber-type differences in maximum specific force [force per cross-sectional area (CSA)] reflect the number of cross bridges present per CSA. Studies were performed on single, Triton X-100-permeabilized rat Diam fibers. Maximum specific force was determined by activation of single Diamfibers in the presence of a high-calcium solution (pCa, −log Ca2+ concentration of 4.0). SDS-PAGE and Western blot analyses were used to determine MHC isoform composition and MHC content per half sarcomere. Differences in maximum specific force across fast MHC isoforms were eliminated when controlled for half-sarcomere MHC content. However, the force produced by slow fibers remained below that of fast fibers when normalized for the number of cross bridges available. On the basis of these results, the lower force produced by slow fibers may be due to less force per cross bridge compared with fast fibers.

Effects of perinatal undernutrition on elimination of immature myosin isoforms in the rat diaphragm

1991 ◽  
Vol 261 (2) ◽  
pp. L49-L54 ◽  
Author(s):  
B. S. Brozanski ◽  
M. J. Daood ◽  
W. A. LaFramboise ◽  
J. F. Watchko ◽  
T. P. Foley ◽  
...  
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Time Course ◽  
Myosin Light Chain ◽  
Diaphragm Muscle ◽  
Myosin Isoforms ◽  
Rat Diaphragm ◽  
Two Dimensional Gel Electrophoresis ◽  
Significant Difference ◽  
Immunocytochemical Techniques

The effect of perinatal undernutrition on the postnatal elimination of immature myosin isoforms in rat diaphragm muscle was examined using electrophoretic and immunocytochemical techniques. Electrophoresis of native myosin showed that neonatal bands were present in diaphragm muscles of both control and undernourished rats on day 4. By day 21, the neonatal bands were diminished in the control diaphragm compared with the diaphragm of the undernourished rats. Neonatal bands persisted on postnatal day 30 in the diaphragm of the undernourished rats but not in the diaphragm of control rats. No significant difference in the time course of elimination of embryonic myosin light chain (LCemb) was observed between the diaphragm muscles of control and undernourished rats with two-dimensional gel electrophoresis. Immunocytochemical analysis demonstrated embryonic myosin heavy chain (MHCemb) in all myofibers of the diaphragm muscle of both groups at day 4, but this isoform was not detected in either group by day 14. Reactivity with anti-neonatal myosin heavy chain (MHCneo) indicated that rate of elimination of the MHCneo was delayed in the undernourished state as compared with the normal rats (P less than 0.001). Serum triiodothyronine levels were measured at 14, 21, and 30 days and were significantly lower in the undernourished rats compared with age-matched controls. These data demonstrate that the normal postnatal decrease in MHCneo, but not MHCemb or LCemb, is affected by the nutritional state of the animal. We speculate that these alterations in myosin isoform transitions are induced by hypothyroidism associated with undernutrition.

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.

scholarly journals Myosin heavy chain changes in heart failure‐rat diaphragm muscle are not related to myogenic regulatory factors expression

2011 ◽  
Vol 25 (S1) ◽  
Author(s):  
Aline Regina Ruiz Lima ◽  
Paula F Martinez ◽  
Ricardo L Damatto ◽  
Marcelo D M Cezar ◽  
Daniele M Guizoni ◽  
...  
Keyword(s):  
Heart Failure ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Diaphragm Muscle ◽  
Rat Diaphragm ◽  
Myogenic Regulatory Factors ◽  
Regulatory Factors

Force-calcium relationship depends on myosin heavy chain and troponin isoforms in rat diaphragm muscle fibers

1999 ◽  
Vol 87 (5) ◽  
pp. 1894-1900 ◽  
Author(s):  
Paige C. Geiger ◽  
Mark J. Cody ◽  
Gary C. Sieck
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Fiber Type ◽  
Muscle Fibers ◽  
Diaphragm Muscle ◽  
Rat Diaphragm ◽  
Single Fibers ◽  
Maximal Force ◽  
Sds Page ◽  
Triton X

The present study examined Ca2+ sensitivity of diaphragm muscle (Diam) fibers expressing different myosin heavy chain (MHC) isoforms. We hypothesized that Diam fibers expressing the MHCslow isoform have greater Ca2+ sensitivity than fibers expressing fast MHC isoforms and that this fiber-type difference in Ca2+ sensitivity reflects the isoform composition of the troponin (Tn) complex (TnC, TnT, and TnI). Studies were performed in single Triton-X-permeabilized Diam fibers. The Ca2+ concentration at which 50% maximal force was generated (pCa50) was determined for each fiber. SDS-PAGE and Western analyses were used to determine the MHC and Tn isoform composition of single fibers. The pCa50 for Diam fibers expressing MHCslow was significantly greater than that of fibers expressing fast MHC isoforms, and this greater Ca2+ sensitivity was associated with expression of slow isoforms of the Tn complex. However, some Diam fibers expressing MHCslow contained the fast TnC isoform. These results suggest that the combination of TnT, TnI, and TnC isoforms may determine Ca2+ sensitivity in Diam fibers.

Denervation alters myosin heavy chain expression and contractility of developing rat diaphragm muscle

2000 ◽  
Vol 89 (3) ◽  
pp. 1106-1113 ◽  
Author(s):  
Gary C. Sieck ◽  
Wen-Zhi Zhan
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Contractile Properties ◽  
Diaphragm Muscle ◽  
Specific Force ◽  
Rat Diaphragm ◽  
Shortening Velocity ◽  
Relative Expression ◽  
Isoform Expression ◽  
Developing Rat

We hypothesized that unilateral denervation (DNV) of the rat diaphragm muscle (Diam) in neonates at postnatal day 7 (D-7) alters normal transitions of myosin heavy chain (MHC) isoform expression and thereby affects postnatal changes in maximum specific force (Po) and maximum unloaded shortening velocity ( V o). The relative expression of different MHC isoforms was analyzed electrophoretically. With DNV at D-7, expression of MHCneo in the Diam persisted, and emergence of MHC2X and MHC2B was delayed. By D-21 and D-28, relative expression of MHC2A and MHC2Bwas reduced in DNV compared with control (CTL) animals. Expression of MHCneo also reappeared in adult Diam by 2–3 wk after DNV, and relative expression of MHC2B was reduced. At each age, Po was reduced and V o was slowed by DNV, compared with CTL. In CTL Diam, postnatal changes in Po and V o were associated with an increase in fast MHC isoform expression. In DNV Diam, no such association existed. We conclude that, in the Diam, DNV induces alterations in both MHC isoform expression and contractile properties, which are not necessarily causally linked.

Diaphragm weakness in pulmonary arterial hypertension: role of sarcomeric dysfunction

2012 ◽  
Vol 303 (12) ◽  
pp. L1070-L1078 ◽  
Author(s):  
Emmy Manders ◽  
Frances S. de Man ◽  
M. L. Handoko ◽  
Nico Westerhof ◽  
Hieronymus W. H. van Hees ◽  
...  
Keyword(s):  
Pulmonary Arterial Hypertension ◽  
Arterial Hypertension ◽  
Myosin Heavy Chain ◽  
Muscle Weakness ◽  
Heavy Chain ◽  
Force Generation ◽  
Diaphragm Muscle ◽  
Maximal Tension ◽  
Pulmonary Arterial ◽  
Diaphragm Weakness

We previously demonstrated that diaphragm muscle weakness is present in experimental pulmonary arterial hypertension (PH). However, the nature of this diaphragm weakness is still unknown. Therefore, the aim of this study was to investigate whether changes at the sarcomeric level contribute to diaphragm weakness in PH. For this purpose, in control rats and rats with monocrotaline-induced PH, contractile performance and myosin heavy chain content of demembranated single diaphragm fibers were determined. We observed a reduced maximal tension of 20% ( P < 0.05), whereas tension cost was preserved in type 2X and 2B diaphragm fibers in PH compared with control. The reduced maximal tension was associated with a reduction of force generated per half-sarcomeric myosin heavy chain content. Additionally, reduced Ca2+ sensitivity of force generation was found in type 2X fibers compared with control, which could exacerbate diaphragm muscle weakness at submaximal activation. No changes in maximal tension and Ca2+ sensitivity of force generation were observed in fibers from the nonrespiratory extensor digitorum longus muscle. Together, these findings indicate that diaphragm weakness in PH is at least partly caused by sarcomeric dysfunction, which appears to be specific for the diaphragm.

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