Effect of Artificial Rearing on the Contractile Properties and Myosin Heavy Chain Isoforms of Developing Rat Tongue Musculature

2003 ◽  
Vol 90 (1) ◽  
pp. 120-127 ◽  
Author(s):  
Stacy A. Kinirons ◽  
Mary S. Shall ◽  
J. Ross McClung ◽  
Stephen J. Goldberg
Keyword(s):  
Myosin Heavy Chain ◽  
Muscle Fiber ◽  
Heavy Chain ◽  
Activity Level ◽  
Contractile Properties ◽  
Artificial Rearing ◽  
Rat Pups ◽  
Decay Times ◽  
Rat Tongue ◽  
Developing Rat

This study's purpose was to examine the influence of an altered activity level, via artificial rearing, on the contractile properties, myosin heavy chain phenotypes (MHC), and muscle fiber sizes of the developing rat tongue retractor musculature. Artificially reared rat pups were fed through a gastric cannula, eliminating nutritive suckling from postnatal day 4 to postnatal day 14. Rat pups were observed immediately following artificial rearing (postnatal day 14) and after a 1-mo resumption of function (postnatal day 42). The contractile characteristics of the tongue retractor musculature were measured in response to stimulation of the hypoglossal nerve. At postnatal day 14, artificially reared rat pups demonstrated significantly longer twitch half-decay times, lower fusion frequencies, and a marked decrease in fatigue resistance. These contractile speed and fatigue characteristics were fully recovered following a 1-mo resumption of function. MHC phenotypes of the styloglossus muscle (a tongue retractor) were determined by gel electrophoresis. At postnatal day 14, artificial rearing had not altered the MHC phenotype or muscle fiber sizes of the styloglossus muscle. However, following a 1-mo resumption of function artificially reared rat pups demonstrated a small but significant increase in MHCIIa expression and decrease in MHCIIb expression compared with dam-reared rats. These results support artificial rearing as a useful model for altering the activity level of the tongue and suggest that normal suckling behavior is necessary for the normal postnatal development of the tongue retractor musculature. This may also be the case for premature infants necessarily fed artificially.

Contractile properties and myosin heavy chain composition of rat tongue retrusor musculature show changes in early adulthood after 19 days of artificial rearing

2006 ◽  
Vol 101 (4) ◽  
pp. 1053-1059 ◽  
Author(s):  
J. Chadwick Smith ◽  
W. Allen Moore ◽  
Stephen J. Goldberg ◽  
Mary S. Shall
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Biceps Brachii ◽  
Early Adulthood ◽  
Time Frame ◽  
Contractile Properties ◽  
Artificial Rearing ◽  
Long Head ◽  
Acute Changes ◽  
Mhc Iib

Previously, we showed that artificial rearing using the “pup in a cup” model results in decreased tongue activity and caused some minor alterations in the tongue retrusor musculature. However, the artificial rearing time frame previously chosen was brief (11 days). The purpose of the present investigation was to extend the artificial rearing period from postnatal days 3 to 21 (P21) to determine whether significant alterations occur as a result of this reduced tongue use. Several changes in contractile properties due to the artificial rearing process were observed, which fully recovered by postnatal days 41 to 42 (P41–2). These changes included a shorter twitch contraction time, shorter twitch half-relaxation time, and decreased fatigue resistance. Styloglossus muscle exhibited more neonatal myosin heavy chain (MHC) isoform at P21 for the artificially reared (AR) group. Changes that were persistent at P41–2 were also observed. Maximum tetanic tension was lower for the AR group at P21 and P41–2 compared with their dam-reared counterparts. Twitch tension was also lower by P41–2 in the AR group. At P41–2, the AR group exhibited an increase in MHC IIa and a decrease in MHC IIb for the styloglossus muscle. In addition, the AR group exhibited a decreased MHC IIb for the long head of the biceps brachii at P41–2. Our results are similar to other models of hindlimb immobilization and suspension. By extending our artificial rearing period, this reduced tongue activity induced acute changes and alterations in the tongue retrusor musculature that persisted into early adulthood.

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.

Pharyngeal myopathy of loaded upper airway in dogs with sleep apnea

1994 ◽  
Vol 76 (4) ◽  
pp. 1746-1752 ◽  
Author(s):  
B. J. Petrof ◽  
A. I. Pack ◽  
A. M. Kelly ◽  
J. Eby ◽  
J. C. Hendricks
Keyword(s):  
Sleep Apnea ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Upper Airway ◽  
Activity Level ◽  
Limb Muscle ◽  
Obstructive Sleep ◽  
Pharyngeal Muscles ◽  
And Control ◽  
Anterior Tibialis

Recent work indicates that upper airway dilator muscles of individuals with obstructive sleep apnea syndrome (OSAS) demonstrate an increased level of activity during wakefulness compared with normal subjects. In addition, massive bursts of pharyngeal dilator activity are associated with the termination of upper airway occlusive events during sleep. This complex pattern of altered pharyngeal dilator activation is also observed in the English bulldog, an animal model of OSAS. In the present study, it was hypothesized that such alterations in activity level might lead to changes in the structure of pharyngeal muscles in the bulldog. Full-thickness biopsies were obtained from two pharyngeal dilator muscles, the sternohyoid (SH) and geniohyoid, as well as a limb muscle, the anterior tibialis, in bulldogs (n = 5) and control dogs (n = 7). Immunohistochemical analysis of myosin heavy chain expression revealed an increased contribution of fast type II myosin heavy-chain fibers to SH in bulldogs. The bulldog SH also demonstrated increased connective tissue content compared with control dogs, consistent with the presence of fibrosis. Both pharyngeal dilators in the bulldog exhibited an elevated proportion of morphologically abnormal fibers indicative of ongoing or prior injury. No differences in any of the above parameters were seen between bulldogs and control dogs in the anterior tibialis limb muscle. We conclude that the chronic load and altered pattern of usage imposed on the upper airway dilators in OSAS lead to myopathic changes that may ultimately impair the ability of these muscles to maintain pharyngeal patency.

scholarly journals Muscle fiber type characterization and myosin heavy chain (MyHC) isoform expression in Mediterranean buffaloes

Meat Science ◽  
2011 ◽  
Vol 88 (3) ◽  
pp. 535-541 ◽  
Author(s):  
C.L. Francisco ◽  
A.M. Jorge ◽  
M. Dal-Pai-Silva ◽  
F.R. Carani ◽  
L.C. Cabeço ◽  
...  
Keyword(s):  
Myosin Heavy Chain ◽  
Muscle Fiber ◽  
Heavy Chain ◽  
Fiber Type ◽  
Muscle Fiber Type ◽  
Isoform Expression

Age-Related Alterations in Myosin Heavy Chain Isoforms in Rat Intrinsic Laryngeal Muscles

2002 ◽  
Vol 111 (11) ◽  
pp. 962-967 ◽  
Author(s):  
Tatsutoshi Suzuki ◽  
Diane M. Bless ◽  
Nadine P. Connor ◽  
Charles N. Ford ◽  
Kyungah Lee ◽  
...  
Keyword(s):  
Myosin Heavy Chain ◽  
Muscle Fiber ◽  
Heavy Chain ◽  
Fiber Type ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Myosin Heavy Chain Isoforms ◽  
Laryngeal Muscles ◽  
Age Related ◽  
Posterior Cricoarytenoid

Deficits in voice and swallowing are found in the elderly, but the underlying neuromuscular mechanisms are unclear. A potential mechanism may be denervation-induced muscle fiber transformation to a slower-contracting type of muscle fiber. This study examined young, old, and denervated rat laryngeal muscles (lateral thyroarytenoid, lateral cricoarytenoid, and posterior cricoarytenoid) to examine differences in myosin heavy chain (MHC) composition. Results of sodium dodecyl sulfate–polyacrylamide gel electrophoresis analyses indicated that all muscles were composed predominately of type IIB MHC. With aging and denervation, type IIB was reduced and type IIX, a slower-contracting isoform, was increased in the lateral thyroarytenoid and lateral cricoarytenoid muscles. In the posterior cricoarytenoid muscle, the MHC composition was relatively unchanged. These findings suggest that aging may affect laryngeal adductory function by altering muscle fiber type composition to a slower-contracting isoform, in a manner similar to that observed with denervation.

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