Tipos de fibras de los músculos intrínsecos laríngeos de seres humanos: una revisión de la literatura / Fiber types in human intrinsic laryngeal muscles: a literature review

El estudio de las fibras musculares permite comprender con mejor detalle la composición de los músculos y sus características funcionales. Además, facilita la aplicación de programas de entrenamiento y rehabilitación basados en las vías energéticas que regulan la contracción muscular. Su estudio generalmente va unido al análisis de las cadenas pesadas de miosina (MyHC), las que informan sobre las características y propiedades funcionales del músculo. El objetivo de este trabajo fue sintetizar la evidencia científica disponible sobre la distribución de fibras musculares y de isoformas de cadenas pesadas de miosina de los músculos intrínsecos de la laringe de seres humanos. Se realizó una revisión sistemática de la literatura mediante el análisis de artículos encontrados en las bases de datos PubMed, EBSCOHost y SciELO. Los hallazgos informan sobre la existencia de fibras tónicas lentas y tipo I, II, IIA y IIX/IIB. Además, se reconoce la presencia de las isoformas MyHC-I, MyHC-IIA, MyHC-IIX, MyHC-Fetal, MyHC-L y MyHC-IIB. En conclusión, los músculos intrínsecos de la laringe presentan una mezcla de fibras y de isoformas de MyHC lentas y rápidas,la que obedece a adaptaciones y cambios evolutivos que han permitido, por ejemplo, las características fonatorias que presenta la voz del ser humano.

The study of muscle fibers allows the composition of muscles and their functional characteristics to be understood in greaterdetail. In addition, it makes it possible to applytraining and rehabilitation programs based on the energypathways that regulatemuscle contraction. Studying muscle fibers is generally associated withthe analysis of myosin heavy chains (MHC) which provide information on the functional characteristics and properties of muscles. The objective of this study was to synthesize the available scientific evidence onthe distribution of muscle fibers and myosin heavy chain isoforms present in the intrinsic laryngeal muscles of human beings. A systematic reviewof the literature was carried outand articles found on PubMed, EBSCOHost,and SciELOwere analyzed.The findings showthe presenceof slow-tonic, type I, type II, type IIA, and type IIX/IIB fibers. Additionally,isoforms MHC-I, MHC-IIA, MHC-IIX, MHC-Fetal, MHC-L, and MHC-IIB canbe found. In conclusion, intrinsic laryngeal muscles are composed ofa combination of slow and fast fibers and MHC isoforms, derived from evolutionary adaptations and changes which have given way, among other things, to the phonetic characteristics ofthe human voice.

Electric acupuncture intervention on the effects of disuse muscular atrophy muscle fiber types of mice / 中国康复医学杂志

Objective:To study the frequency of electrical stimulation affect the atrophy recovery of mouse soleus muscle.Method:Sixty mice,30 of them were randomly divided into blank control group (Con) and atrophy model group (Atro) and validated this model after 1 week.The other 30 mice were randomly divided into three groups:the natural recovery group (Rec),the exercise intervention group (Exer),the electroacupuncture intervention group (Elec) after making them atrophy.Atrophy model group were plaster fixed one week.Natural recovery group was natural fed two weeks after removing the plaster.Exercise intervention group runs 1 hour at 16m/min speed two weeks.EA intervention group were stimulated 15min daily for 2 weeks on hind limb,with pulse duration 0.35ms,frequency 50Hz,for 2 weeks.Frozen sections and Immunofluorescence were used to measure the cross-sectional area of muscle fibers.ATPase staining was used to detect the muscle fiber type changing,and Western Blot to detect soleus muscle Troponin I-SS (TNNI1) and Troponin I-FS (TNNI2) protein expression.Result:The soleus muscle in Atro group showed significant change in cross-sectional area and wet weight compared with Con group(P＜0.01),The expression of TNNI1 and TNNI2 protein was also significantly different from that of Con group (P＜0.05).Compared with the Rec group,the cross-sectional area of slow muscle and fast muscle in the Exer and Elec groups significantly increased (P＜0.05),TNNI1 protein expression significant ly increased (P＜0.01),TNNI2 protein was no significant difference detected(P＞0.05).Conclusion:The middle low frequency electroacupuncture intervention can effectively increase the cross-sectional area of muscle fibers,in particular,increase the TNNI1 and TNNI2 protein expression of slow muscle fibers.It is as effective as exercise intervention to promote recovery of disuse muscular atrophy.

Composition and distribution of muscle fiber types in the rat gastrocnemius muscle / 重庆医科大学学报

Objective:To study the composition and distribution of two muscle fiber types in SD rat gastrocnemius muscle in order to learn its function.Methods:Gastrocnemius muscles of both sides of hind limbs were collected from 10 adult SD rats.8-?m-thick cryostat sections were transected and then stained with the method of myosin-ATPase following a procesure modified partially from one that Guth & Samaha reported before.Results:Gastrocnemius muscle from SD rats can be clearly identified with two different fiber types which are typeⅠ(slow twitch fiber)and typeⅡ(fast twitch fiber) by the myosin-ATPase staining method.Fibers of type I are stained white while fibers of type II are stained brown.The distribution pattern of two types of muscle fibers in gastrocnemius muscles is uniform and chessboard-like.The proportion of typeⅡmuscle fibers contained in the muscle is(72.2?6.8)%,much higher than that of typeⅠfibers which is(27.8?2.4)%(P

Modified procedure for the histochemical demonstration of myosin ATPase / 西安交通大学学报(医学版)

Objective To study the effect of self-modified Guth & Samaha's myosin-ATPase staining method on the classification of SD rat skeletal muscle fiber types.Methods 8 ?m-thick cryostat sections from rat chest muscles and biceps brachii muscles were transfected with cryostat.Myosin-ATPase staining was carried out according to the following procedure: ① Fixing sections for 5 min in fixative solution containing 40 g/L paraformaldehyde;② Rinsing slides in Tris-rinse solution and then preincubating them in alkaline preincubation solution for 15 min;③ Rinsing slides in Tris-rinse solution twice and then incubating them for 60 min in incubation solution;④ Washing slides for three times in 10 g/L CaCl2 and then placing them in 20 g/L CoCl2 for 3 min;⑤ Washing sides in distal water and then placing them in 10 g/L(NH4)2S for 3 min and;⑥ Washing slides in running tap water for 3 min,dehydrating in graded ethanol,clearing in xylene and mounting in neutral balsam.Results After being stained by modified myosin-ATPase staining method,both chest muscle and biceps brachii muscle samples from SD rats could be clearly identified as type Ⅰ fibers and type Ⅱfibers as the fibers of type Ⅰ were stained white while the fibers of type Ⅱ were stained brown.Conclusion Modified myosin-ATPase staining method is a simple and effective way for muscle fiber type classification and can be applied in skeletal muscle related study.