• Title/Summary/Keyword: Contraction force

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AgNW-based functional polymer cantilever to improve maturity and contractility of cardiomyocytes (심근세포 성숙도 및 수축력 향상을 위한 AgNW 기반의 기능성 폴리머 캔틸레버)

  • Jeung, Min-young;Sim, Yu-ri;Yun, Ha-young;Kim, Dong-Su;Lee, Dong-Weon
    • Journal of Sensor Science and Technology
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    • v.30 no.3
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    • pp.185-189
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    • 2021
  • Herein, we propose a functional polymer cantilever to enhance maturation and contractile force of cardiomyocytes. The proposed cantilever consists of a surface-patterned polymer substrate and silver nanowires (AgNWs). The AgNWs are transferred to the PDMS substrate using conventional molding techniques. This thin metallic surface significantly improves the adhesion of cardiomyocyte on the surface-patterned PDMS with the hydrophobic characteristics. In addition, the use of AgNWs improves the visibility of the conducting PDMS substrate for the observation of cardiomyocyte through an inverted microscope. The AgNWs also assist in synchronizing each cardiomyocyte to maximize its contractile force.

The Effects of Fructose on Contractility of Isolated Rat Atria Depressed with Lidocaine (Lidocaine에 의해 억제된 심근수축력에 대한 Fructose의 영향)

  • Ko Kye-Chang;Sohn Chi-Dong;Jung Jee-Chang
    • The Korean Journal of Pharmacology
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    • v.22 no.1 s.38
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    • pp.51-59
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    • 1986
  • The effect of metabolic substrate fructose on the force of contraction of isolated rat atria depressed with lidocaine was determined. Fructose produced dose-dependent increase in the force of contraction of isolated atria depressed by substrate-free Krebs-Ringer bicarbonate medium. The maximally effective concentration of fructose was 30 mM. The isolated atria, suspended in Krebs-Ringer bicarbonate glucose medium aerated with 95% $O_2-5%CO_2$at $30^{\circ}C$ and pH 7.4, were depressed 50% by approximately 2.34 mg/100 ml of lidocaine. Addition of 30 mM fructose to these depressed atria resulted in a marked increase in the contractile force similar to that with pyruvate and acetate. Fructose had no significant effect, however, on atria exposed to low-calcium medium. The results are consistent with a previous report suggesting blockade by lidocaine of the uptake or utilization of glucose in the glycolytic pathway, and further pinpoint the blockade as an early step in the glycolytic sequence prior to the phospho-fructokinase step.

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Relatoinship between Sarcoplasmic Reticular Calcium Release and $Na^+-Ca^{2+}$ Exchange in the Rat Myocardial Contraction

  • Kim, Eun-Gi;Kim, Soon-Jin;Ko, Chang-Mann
    • The Korean Journal of Physiology and Pharmacology
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    • v.4 no.3
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    • pp.197-210
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    • 2000
  • Suppressive role of $Na^+-Ca^{2+}$ exchange in myocardial tension generation was examined in the negative frequency-force relationship (FFR) of electric field stimulated left atria (LA) from postnatal developing rat heart and in the whole-cell clamped adult rat ventricular myocytes with high concentration of intracellular $Ca^{2+}$ buffer (14 mM EGTA). LA twitch amplitudes, which were suppressed by cyclopiazonic acid in a postnatal age-dependent manner, elicited frequency-dependent and postnatal age-dependent enhancements after $Na^+-reduced,\;Ca^{2+}-depleted$ (26 Na-0 Ca) buffer application. These enhancements were blocked by caffeine pretreatment with postnatal age-dependent intensities. In the isolated rat ventricular myocytes, stimulation with the voltage protocol roughly mimicked action potential generated a large inward current which was partially blocked by nifedipine or $Na^+$ current inhibition. 0 Ca application suppressed the inward current by $39{\pm}4%$ while the current was further suppressed after 0 Na-0 Ca application by $53{\pm}3%.$ Caffeine increased this inward current by $44{\pm}3%$ in spite of 14 mM EGTA. Finally, the $Na^+$ current-dependent fraction of the inward current was increased in a stimulation frequency-dependent manner. From these results, it is concluded that the $Ca^{2+}$ exit-mode (forward-mode) $Na^+-Ca^{2+}$ exchange suppresses the LA tension by extruding $Ca^{2+}$ out of the cell right after its release from sarcoplasmic reticulum (SR) in a frequency-dependent manner during contraction, resulting in the negative frequency-force relationship in the rat LA.

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Introduction of Bong Chuna Manual Therapy (봉 추나요법의 개요)

  • Oh, Won-Kyo;Shin, Byung-Cheul
    • The Journal of Churna Manual Medicine for Spine and Nerves
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    • v.2 no.1
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    • pp.99-114
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    • 2007
  • Objectives : The purpose of this study was to introduce the Chuna Manual Therapy (CMT) using Bong (a type of stick which is called 'bong') as a part of Oriental Medicine. Methods : We searched several traditional methods of CMT using Bong, either individual contact to specialist of CMT using Bong or referred to publications, and summarized briefly for introduction. Authors also made a comparative study between existing CMT and CMT using the bong. Results & Conclusions : The indications of Bong CMT are regarded as acute or chronic pain syndrome, whiplash associated disorders, facet syndrome, vertebral misalignment, chronic fatigue syndrome, obesity and also lower extremity length difference caused by malalignment of vertebrae and pelvic bone. The Meridian Muscle Therapy by pressing down using the Bong can be carried out on the imbalances of the muscle by shortening and lengthening contraction. CMT with Bong is considered more effective than other existing CMT in terms of effectiveness. In the case of pelvic correction which needs a tremendous amount of force, it can reduce the force required effectively. This fact can be inferred by the theory of composition and decomposition of force during the transmission of power. We can perform Bong CMT feeling less fatigued subsequently than general CMT. Pressing down with flexed fingers to grip bong acts on the contraction of flexor digiti and extensor digiti muscle, this protects the $doctor^{\circ}{\emptyset}s$ wrist joints from injury. The bong which acts as a tool between the doctor and the patient, while being given treatment, absorbs and spreads out the direct impact from the patient to the doctor. CMT with Bong is able to apply to both existing massage therapies with the hand. The bong appliance can be used in all applications, particularly, but not limited to; Orthopedic and Manual Correction Therapy, Meridian Muscle Pressing, Exercise Therapy, and Meridian Point Manual Pressing Therapy. CMT with Bong belongs to the category of oriental rehabilitation and Chuna manual medicine.

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The Acute Effect of Trimetazidine on the High Frequency Fatigue in the Isolated Rat Diaphragm Muscle

  • Emre, Mustafa;Karayaylali, Lbrahim;San, Mustafa;Demirkazik, Ayse;Kavak, Servet
    • Archives of Pharmacal Research
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    • v.27 no.6
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    • pp.646-652
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    • 2004
  • The objective of this study was to determine the acute effect of trimetazidine (TMZ) on the pre-fatigue, fatigue and post-fatigue contractile characteristics and tension-frequency relationships of isolated rat diaphragm muscle. Muscle strips were taken from the ventral-costal aspects of the diaphragm muscle of rats killed by decapitation. The muscle strips were suspended in organ baths containing Krebs solution, with a gas mixture of 95% $O_2$ and 5% $CO_2$ at $37^{\circ}C$ and pH 7.35-7.45. After determining the thermoregulation and optimum muscle length the muscles were subjected to direct supramaximal stimulation with 0.05 Hz frequency square pulses for periods of 0.5 msec to obtain control values. After adding $5{\times}10^{-6}{\;}and{\;}5{\times}10^{-5}$ M trimetazidine solution to the respective bath media, the contractile parameters of the muscles were recorded. The contractile parameters were also recorded for both the trimetazidine and tri-metazidine-free media after application of the high frequency fatigue protocols. Later, the tension-frequency relationship was determined by applying stimulating pulses of 10, 20, 50 and 100 Hz to the muscle strips. Whilst the twitch tension obtained from the $5{\times}10^{-6}{\;}and{\;}5{\times}10^{-5}$ M trimetazidine media showed numerical increases compared to that of the controls, these were not statistically significant (p>0.05). The contraction time exhibited a dose dependent increase (p<0.001), whilst the contraction and relaxation rates did not differ significantly. The isometric contraction forces obtained with the different stimulating frequencies showed a significant increase in the tetanic contraction only at 100 Hz (p<0.05). A comparison of the pre- and post-fatigue twitch tensions in the trimetazidine media showed the post- fatigue twitch tensions to be significantly higher than those of the pre-fatigue contraction forces (p<0.05). In the $5{\times}10^{-6}{\;}and{\;}5{\times}10^{-5}$ M trimetazidine media the increases in the post-fatigue contraction force were 22 and 30%, respectively. These results demonstrated that in isolated rat diaphragm muscle, TMZ significantly limited the mechanical performance decrease during fatigue. It is our opinion that trimetazidine contributed to the observed fatigue tolerance by eliminating the factors of fatigue, due to preservation of intracellular calcium homeostasis, provision of the ATP energy levels needed by ATPase dependent pumps and especially by keeping the intracellular pH within cer-tain limits.

Effects of Banhaonpaetang(半夏溫肺湯) extract and its Constituent herbs on the Contraction of Isolated Guinea Pig Trachea Smooth Muscle (반하온폐탕(半夏溫肺湯) 및 그 구성약물(構成藥物)이 실험(實驗) 동물(動物)에 미치는 영향(影響))

  • Song, Jin-Oh;Han, Sang-Hwan
    • The Journal of Internal Korean Medicine
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    • v.13 no.2
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    • pp.1-15
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    • 1992
  • This study has been carried out to investigate the effects of Banhaonpaetang extract and its constituent herbs on the contractile force of Isolated Guinea pig trachea smooth muscle and to elucidate its mechanism. The results were as follows; 1. Banhaonpaetang significanly inhibitd the contractile force of isolated guinea pig trachea smooth muscle pretreated by histamine. 2. Banhaonpaetang significantly inhibited the contractile force of isolated guinea pig trachea smooth muscle pretreated by acetylcholine. 3. Radix Asari(細辛), Flos Inulae(旋覆花), Pericarpium Citri Nobilis(陳皮) and Radix Ginseng(人蔘) extract significantly inhibited the contractile force of isolated guinea pig trachea smooth muscle pretreated by histamine. 4. Radix Asari(細辛), Cortex Cinnamomi(桂心), Flos Inulae(旋覆花), Pericarpium Citri Nobilis(陳皮) and Radix Ginseng(人蔘) extract significantly inhibited the contractile force of isolated guinea pig trachea smooth muscle pretreated by acetylcholine. 5. The effects of Banhaonpaetang extract on the changes of plasma ACTH in rats were shown to be insignificant. 6. The effects of Banhaonpaetang extract on the changes of serum electrolytes were shown to be significant in $K^+$ and $Ca^{2+}$.

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A Comparison of Muscle Contraction Using Functional Electrical Stimulation: Intermittent High Frequency Alternating Stimulation Versus Intermittent Low Frequency Synchronous Stimulation (기능적 전기자극기를 이용한 간헐적 고주파 교대자극과 간헐적 저주파 동시자극의 근 수축력 비교)

  • Song, Young-Hee;Cho, Sang-Hyun;Lee, Young-Hee
    • Physical Therapy Korea
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    • v.9 no.2
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    • pp.115-131
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    • 2002
  • Functional electrical stimulation (FES) training of the knee extensors is a useful way to rehabilitate the ability to stand and walk. However, training using FES has not been able to solve the problem of fatigue; clinical application of FES quickly produces muscle fatigue, due to the continuous activation of the muscles of the lower extremity. Therefore, reduction of muscle fatigue is an important factor in increasing the effectiveness of FES training in paraplegia. Intermittent high frequency alternating stimulation is a method that combines the advantages of high frequency (leading to strong muscle contractions) and alternating stimulation (reducing muscle fatigue), thereby continuously strengthening muscles. It is not known whether low frequency simultaneous stimulation results in stronger muscle contraction than high frequency alternating stimulation. This study compared the effectiveness of high frequency alternating stimulation with low frequency synchronized stimulation. Muscle power using FES on the quadriceps of 20 normal subjects were compared. Intermittent high frequency alternating stimulation did not produce more powerful muscle contraction than intermittent low frequency synchronized stimulation, because the muscle characteristics differed individually. Significant individual variation according to muscle characteristics was founded when applying FES. Accordingly, when physical therapists use FES to treat patients, they must be aware of individual variation in muscle characteristics.

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Immediate Effect of Neuromuscular Electrical Stimulation on Balance and Proprioception During One-leg Standing

  • Je, Jeongwoo;Choi, Woochol Joseph
    • Physical Therapy Korea
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    • v.29 no.3
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    • pp.187-193
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    • 2022
  • Background: Neuromuscular electrical stimulation (NMES) is a physical modality used to activate skeletal muscles for strengthening. While voluntary muscle contraction (VMC) follows the progressive recruitment of motor units in order of size from small to large, NMES-induced muscle contraction occurs in a nonselective and synchronous pattern. Therefore, the outcome of muscle strengthening training using NMES-induced versus voluntary contraction might be different, which might affect balance performance. Objects: We examined how the NMES training affected balance and proprioception. Methods: Forty-four young adults were randomly assigned to NMES and VMC group. All participants performed one-leg standing on a force plate and sat on the Biodex (Biodex R Corp.) to measure balance and ankle proprioception, respectively. All measures were conducted before and after a training session. In NMES group, electric pads were placed on the tibialis anterior, gastrocnemius, and soleus muscles for 20 minutes. In VMC group, co-contraction of the three muscles was conducted. Outcome variables included mean distance, root mean square distance, total excursion, mean velocity, 95% confidence circle area acquired from the center of pressure data, and absolute error of dorsi/plantarflexion. Results: None of outcome variables were associated with group (p > 0.35). However, all but plantarflexion error was associated with time (p < 0.02), and the area and mean velocity were 37.0% and 18.6% lower in post than pre in NMES group, respectively, and 48.9% and 16.7% lower in post than pre in VMC group, respectively. Conclusion: Despite different physiology underlying the NMES-induced versus VMC, both training methods improved balance and ankle joint proprioception.

Cardiac Pharmacology of Anesthetics (마취제(痲醉劑)의 심장약리학적(心臟藥理學的) 연구(硏究) 제2보(第2報) 각종대사기질(各種代謝基質)에 대(對)한 Halothane 저하유이심방(低下遊離心房)의 수축반응(收縮反應))

  • Ko, Kye-Chang;Jung, Jee-Chang;Han, Dae-Sup
    • The Korean Journal of Pharmacology
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    • v.10 no.1 s.15
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    • pp.55-59
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    • 1974
  • Further elucidation of the mechanism of halothane's negative inotropic action has resulted from a study of the effect of various substrates on halothane-depressed rat atria. Approximately 6 mg% halothane was required to maintain a 50% depression of the contractility of rat atria suspended in a modified Krebs-Ringer bicarbonate glucose medium, pH 7.4, $30^{\circ}C$ for 2hr. Both lactate and acetate were found to restore partially the contractility of halothane-depressed atria. The maximally effective concentration of lactate was 5 mM; for acetate it was 2.5mM. Neither 5 nor 20 mM of additional glucose was effective in restoring the force of contraction of halothane-depressed atria. The results are consistent with the hypothesis that halothane exerts at least a part of its negative inotropic effect on rat atria by inhibiting either the uptake or utilization of glucose by the myocardium. The site of blockade must be prior to the conversion of pyruvate to acetyl CoA. In our previous report dealing with the mechanism of cardiac depressant action of inhalation anesthetic halothane, it has been demonstrated that: 1) approximately 6 mg/100 ml halothane is required to maintain 50% depression of the force of contraction of isolated rat atria in Krebs-Ringer bicarbonate glucose medium; 2) pyruvate partially restores the contractility of halothane-depressed atria, but has no effect on normal atria; the partial recovery of depressed atria by the addition of sodium pyruvate is due to the effect of the pyruvate ion itself, not to the sodium ion; 4) addition of pyruvate, to atria depressed with hypertonic medium, produced only further depression. From these findings we concluded that the cardiac depressant action of halothane on rat atria is a manifestation of inhibition of glucose uptake or utilization. The present studies were undertaken to observe the effect of other substrates on halothane-depressed atria in order to substantiate our conclusion. As with the case of pyruvate, lactate and acetate also partially restored the force of contraction of halothane-depressed atria. These data are consistent with the hypothesis that halothane inhibits glucose uptake or utilization in the glycolytic cycle of the myocardium.

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Effects of potassium channel modulators on the fatigue velocity of mouse skeletal muscle (K+ 통로 조절 약물이 마우스 골격근의 피로현상에 미치는 영향)

  • Lee, Ki-ho;Ryu, Pan-dong;Lee, Mun-han;Lee, Hang
    • Korean Journal of Veterinary Research
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    • v.35 no.2
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    • pp.245-254
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    • 1995
  • The density of ATP-sensitive potassium($K_{APT}$) channels, that open as intracellular ATP concentration falls below a critical level, is very high in skeletal muscle surface membrane and those high density may imply that $K_{ATP}$ channels have very important physiological roles. To elucidate a role of $K_{ATP}$ in relation to fatigue, the modulating effects of potassium channel openers and blockers on the fatigue velocity(FV) of mouse extensor hallucis longus muscle(EHL) were investigated in vitro. Twitch contraction was induced by an electrical field stimulation (EFS: 24-48V, 20ms, 0.2-4Hz) and resulting contraction force was isometrically recorded. The twitch forces were gradually decreased to 25% of initial contraction force(ICF) in $37.52{\pm}1.55sec$($mean{\pm}s.e.m.$, n=135), indicating the fatigue phenomena. The mean velocity for development of the fatigue was measured during the period that twitch force decreased to half($FV_{0/0.5}$) and during the period from half to 25%($FV_{0.5/0.25}$) of ICF. The fatigue was induced once every one hour and the tissue response was stable for up to 4 hours. In control condition, ICF was $5.8{\pm}0.12g$ (n=144) and decreased to 50% of ICF with the mean fatigue velocity of $0.182{\pm}0.006g/sec$($FV_{0/0.5}$, n=135) and from 50% to 25% of ICF with $0.084{\pm}0.004g/sec$($FV_{0.5/0.25}$, n=135). Cromakalim($50{\mu}M$) significantly increased $FV_{0.5/0.25}$(n=4). Glibenclamide($IC_{50}>50{\mu}M$), $Ba^{2+}$($IC_{50}=10{\mu}M$), 4-aminopyridine($FV_{0/0.5}$, $IC_{50}=0.5mM$; $FV_{0.5/0.25}$, $IC_{50}=2mM$) decreased both $FV_{0/0.5}$ and $FV_{0.5/0.25}$ concentration-dependently up to 75%. $TEA^+$(30mM), E-4031($10{\mu}M$), tolbutamide(1mM) decreased $FV_{0.5/0.25}$, but apamin(300nM) and $TEA^+$(10mM) showed no significant effects. Our results suggest that activation of the $K_{ATP}$ channels may be major cause of $K^+$ outflux during development of the fatigue and the isolated EHL muscle could be an useful experimental preparation in studying the fatigue phenomena in skeletal muscle. In addition, the possibility of activation of delayed rectifier during the fatigue development remains to be studied further.

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