Alterations in fast‐twitch muscle membrane conductance regulation do not explain decreased muscle function of SOD1 G93A rats

2021 ◽  
Author(s):  
Pieter A. Leermakers ◽  
Martin Skov ◽  
Anders Riisager ◽  
Ole B. Nielsen ◽  
Thomas H. Pedersen
Keyword(s):  
Muscle Function ◽  
Membrane Conductance ◽  
Muscle Membrane ◽  
Fast Twitch Muscle ◽  
Fast Twitch

Dynamics and Consequences of Potassium Shifts in Skeletal Muscle and Heart During Exercise

2000 ◽  
Vol 80 (4) ◽  
pp. 1411-1481 ◽  
Author(s):  
Ole M. Sejersted ◽  
Gisela Sjøgaard
Keyword(s):  
Skeletal Muscle ◽  
Force Production ◽  
Membrane Conductance ◽  
Cell Swelling ◽  
Modifying Factors ◽  
Fast Twitch Muscle ◽  
T Tubules ◽  
Exercise Induced ◽  
Fast Twitch ◽  
Muscle Excitability

Since it became clear that K+shifts with exercise are extensive and can cause more than a doubling of the extracellular [K+] ([K+]s) as reviewed here, it has been suggested that these shifts may cause fatigue through the effect on muscle excitability and action potentials (AP). The cause of the K+shifts is a transient or long-lasting mismatch between outward repolarizing K+currents and K+influx carried by the Na+-K+pump. Several factors modify the effect of raised [K+]sduring exercise on membrane potential ( Em) and force production. 1) Membrane conductance to K+is variable and controlled by various K+channels. Low relative K+conductance will reduce the contribution of [K+]sto the Em. In addition, high Cl−conductance may stabilize the Emduring brief periods of large K+shifts. 2) The Na+-K+pump contributes with a hyperpolarizing current. 3) Cell swelling accompanies muscle contractions especially in fast-twitch muscle, although little in the heart. This will contribute considerably to the lowering of intracellular [K+] ([K+]c) and will attenuate the exercise-induced rise of intracellular [Na+] ([Na+]c). 4) The rise of [Na+]cis sufficient to activate the Na+-K+pump to completely compensate increased K+release in the heart, yet not in skeletal muscle. In skeletal muscle there is strong evidence for control of pump activity not only through hormones, but through a hitherto unidentified mechanism. 5) Ionic shifts within the skeletal muscle t tubules and in the heart in extracellular clefts may markedly affect excitation-contraction coupling. 6) Age and state of training together with nutritional state modify muscle K+content and the abundance of Na+-K+pumps. We conclude that despite modifying factors coming into play during muscle activity, the K+shifts with high-intensity exercise may contribute substantially to fatigue in skeletal muscle, whereas in the heart, except during ischemia, the K+balance is controlled much more effectively.

scholarly journals Adrenergic control of vascular resistance varies in muscles composed of different fiber types: influence of the vascular endothelium

2011 ◽  
Vol 301 (3) ◽  
pp. R783-R790 ◽  
Author(s):  
Bradley J. Behnke ◽  
Robert B. Armstrong ◽  
Michael D. Delp
Keyword(s):  
Blood Flow ◽  
Vascular Resistance ◽  
Vascular Endothelium ◽  
Fold Increase ◽  
Male Rats ◽  
Type I ◽  
Fiber Types ◽  
Fast Twitch Muscle ◽  
Dose Responses ◽  
Fast Twitch

The influence of the sympathetic nervous system (SNS) upon vascular resistance is more profound in muscles comprised predominately of low-oxidative type IIB vs. high-oxidative type I fiber types. However, within muscles containing high-oxidative type IIA and IIX fibers, the role of the SNS on vasomotor tone is not well established. The purpose of this study was to examine the influence of sympathetic neural vasoconstrictor tone in muscles composed of different fiber types. In adult male rats, blood flow to the red and white portions of the gastrocnemius (GastRed and GastWhite, respectively) and the soleus muscle was measured pre- and postdenervation. Resistance arterioles from these muscles were removed, and dose responses to α1-phenylephrine or α2-clonidine adrenoreceptor agonists were determined with and without the vascular endothelium. Denervation resulted in a 2.7-fold increase in blood flow to the soleus and GastRed and an 8.7-fold increase in flow to the GastWhite. In isolated arterioles, α2-mediated vasoconstriction was greatest in GastWhite (∼50%) and less in GastRed (∼31%) and soleus (∼17%); differences among arterioles were abolished with the removal of the endothelium. There was greater sensitivity to α1-mediated vasoconstriction in the GastWhite and GastRed vs. the soleus, which was independent of whether the endothelium was present. These data indicate that 1) control of vascular resistance by the SNS in high-oxidative, fast-twitch muscle is intermediate to that of low-oxidative, fast-twitch and high-oxidative, slow-twitch muscles; and 2) the ability of the SNS to control blood flow to low-oxidative type IIB muscle appears to be mediated through postsynaptic α1- and α2-adrenoreceptors on the vascular smooth muscle.

scholarly journals High-speed jaw-opening exercise in training suprahyoid fast-twitch muscle fibers

2018 ◽  
Vol Volume 13 ◽  
pp. 125-131 ◽  
Author(s):  
Mariko Matsubara ◽  
Haruka Tohara ◽  
Koji Hara ◽  
Hiromichi Shinozaki ◽  
Yasuhiro Yamazaki ◽  
...  
Keyword(s):  
High Speed ◽  
Muscle Fibers ◽  
Jaw Opening ◽  
Fast Twitch Muscle ◽  
Fast Twitch

scholarly journals lncRNA-Six1 Is a Target of miR-1611 that Functions as a ceRNA to Regulate Six1 Protein Expression and Fiber Type Switching in Chicken Myogenesis

Cells ◽  
2018 ◽  
Vol 7 (12) ◽  
pp. 243 ◽  
Author(s):  
Manting Ma ◽  
Bolin Cai ◽  
Liang Jiang ◽  
Bahareldin Ali Abdalla ◽  
Zhenhui Li ◽  
...  
Keyword(s):  
Fiber Type ◽  
Muscle Fibers ◽  
Muscle Fiber Types ◽  
Fiber Types ◽  
Proliferation And Differentiation ◽  
Slow Twitch Muscle ◽  
Fast Twitch Muscle ◽  
Slow Twitch ◽  
Slow Twitch Fibers ◽  
Fast Twitch

Emerging studies indicate important roles for non-coding RNAs (ncRNAs) as essential regulators in myogenesis, but relatively less is known about their function. In our previous study, we found that lncRNA-Six1 can regulate Six1 in cis to participate in myogenesis. Here, we studied a microRNA (miRNA) that is specifically expressed in chickens (miR-1611). Interestingly, miR-1611 was found to contain potential binding sites for both lncRNA-Six1 and Six1, and it can interact with lncRNA-Six1 to regulate Six1 expression. Overexpression of miR-1611 represses the proliferation and differentiation of myoblasts. Moreover, miR-1611 is highly expressed in slow-twitch fibers, and it drives the transformation of fast-twitch muscle fibers to slow-twitch muscle fibers. Together, these data demonstrate that miR-1611 can mediate the regulation of Six1 by lncRNA-Six1, thereby affecting proliferation and differentiation of myoblasts and transformation of muscle fiber types.

Alpha-actin and cytochrome c mRNAs in atrophied adult rat skeletal muscle

1988 ◽  
Vol 254 (5) ◽  
pp. C651-C656 ◽  
Author(s):  
P. Babij ◽  
F. W. Booth
Keyword(s):  
Skeletal Muscle ◽  
Cytochrome C ◽  
Muscle Atrophy ◽  
Weight Bearing ◽  
Skeletal Muscle Atrophy ◽  
Rna Content ◽  
Mrna Content ◽  
Fast Twitch Muscle ◽  
Alpha Actin ◽  
Fast Twitch

Specific complementary DNA (cDNA) hybridization probes were used to estimate the levels of alpha-actin and cytochrome c mRNAs and also 18S rRNA in three models of skeletal muscle atrophy. After 7 days of hindlimb suspension, or immobilization, or denervation, protein content decreased 26-32% in all muscles studied except suspended fast-twitch muscle, which lost only half as much protein. alpha-Actin mRNA content decreased 51-66% and cytochrome c mRNA content decreased 42-61% in slow- and fast-twitch muscles in all three models of atrophy. However, total RNA content did not show similar directional changes; RNA content decreased 27-44% in suspended and immobilized muscle but was unchanged in denervated fast-twitch muscle. The results were interpreted to suggest that loss of weight-bearing function of skeletal muscle is a major factor affecting the levels of alpha-actin and cytochrome c mRNAs during muscle atrophy.

scholarly journals Experimentally induced differentiation of slow tonic and fast twitch muscles in the chick

1979 ◽  
Vol 36 (1) ◽  
pp. 137-154
Author(s):  
D.E. Ashhurst ◽  
G. Vrbova
Keyword(s):  
Latissimus Dorsi ◽  
Neuromuscular Junctions ◽  
Morphological Characteristics ◽  
Morphological Features ◽  
Contractile Properties ◽  
The Other ◽  
Induced Differentiation ◽  
Anterior Latissimus Dorsi ◽  
Fast Twitch Muscle ◽  
Fast Twitch

The anterior latissimus dorsi (ALD) muscle of chickens is a slow tonic muscle, while the posterior latissimus dorsi (PLD) is a fast twitch muscle. These muscles on opposite sides of a 3-week-old chick were removed, minced and replaced in the site of the other muscle and left to regenerate. The regenerating muscles were examined at various periods from 4 days onwards and their contractile properties were found to resemble those typical of the muscle they replaced and not the original muscle. The regenerating muscles from 8 days onwards displayed the morphological features of the control muscles in the contralateral site. By 14 days, differentiation was almost complete and neuromuscular junctions were seen. It is suggested that the physiological and morphological characteristics of a muscle are determined by its position and possibly also by its innervation.

scholarly journals Regulation of Force Dynamics in Fast Twitch Muscle

2010 ◽  
Vol 24 (S1) ◽  
Author(s):  
Willemijn Groenendaal ◽  
Jeroen Jeneson ◽  
Robert Wiseman ◽  
Klaas Nicolay ◽  
Peter Hilbers ◽  
...  
Keyword(s):  
Force Dynamics ◽  
Fast Twitch Muscle ◽  
Fast Twitch
Sign in / Sign up

Export Citation Format

Share Document