• YAKHAK HOEJI
• /
• v.43 no.5
• /
• pp.659-664
• /
• 1999

To investigate the difference of contractile mechanism between KCI and phenylephrine-induced contraction, we observed effects of $Ca^{2+}$ antagonists and protein kinase inhibitors on aorta contraction of rats. Verapamil dose-dependently inhibited the contraction induced by KCI and phenylephrine, the inhibitory effect of verapamil was more potent in KCI-induced contraction than phenylephrine-induced contraction. Econazole and TMB-8 significantly inhibited CKI-induced contraction but did not inhibit phenylephrine-induced contraction. Staurosporine dose-dependently inhibited both KCI and phenylephrine-induced contraction. Genistein and calmodulin antagonists (W-7 and trifluoperazine) also inhibited both contraction in a dose dependent manner. However, the inhibitory effects of genistein and calmodulin antagonists were more potent in phenylephrine-induced contraction than KCI-induced contraction. These results suggest that involvements of $Ca^{2+}$ channel and protein kinase in rat aorta contraction were dependent on agonist causing aorta smooth muscle contraction.

• The Korean Journal of Physiology
• /
• v.29 no.2
• /
• pp.225-232
• /
• 1995

The present study was conducted to evaluate the effect of phorbol 12,13-dibutyrate (PDBu) on the contraction of rabbit jugular vein in vitro. PDBu concentrations of greater than 10 nM induced a periodic contraction which was composed of rapid contraction, plateau and slow relaxation. The frequency of periodic contraction increased as PDBu concentration increased. The PDBu-induced contraction was inhibited by staurosporine (100 nM), it was not changed by tetrodotoxin $(1\;{\mu}M).$ In $Ca^{2+}$-free medium, PDBu induced a sustaining contraction, but not periodic contraction. Addition of $Ca^{2+}$ to medium evoked periodic contraction which was inhibited by nifedipine, PDBu concentrations of greater than $0.1\;{\mu}M$ increased ^{45}Ca^{2+}$ uptake without changing $^{45}Ca^{2+}$ efflux. Charybdotoxin and apamin, $Ca^{2+}$-activated K^{+}$ channel blockers, did not affect the PDBu-induced periodic contraction, whereas tetraethylammonium (TEA) abolished the periodicity. Pinacidil $(10\;{\mu}M).$, a potassium channel activator, blocked PDBu induced periodic contraction, which was recovered by glybenclamide $(10\;{\mu}M).$. In high potassium solution, PDBu did not produce the periodic contraction. These results suggest that the PDBu-induced periodicity of contraction is modulated by voltage dependent $Ca^{2+}$ channel and ATP-sensitive $K^{+}$ channel.

• The Journal of Korean Physical Therapy
• /
• v.24 no.4
• /
• pp.262-267
• /
• 2012

Purpose: This study was designed to analyze the differences in cerebral cortex activity of the elderly after extracting the movement related cortical potentials (MRCPs) from electroencephalogram (EEG) during a concentric and eccentric contraction of the elbow joint flexors, and entering them into the brain-mapping program to make the images. Methods: Right-dominant normal elderly people were divided into an eccentric contraction group and a concentric contraction group. Then, their MRCPs were measured using EEG and sEMG, during an eccentric and concentric contraction. Then, they were converted into images using the brain-mapping program. Results: Eccentric contraction group's $C_3$ and Cz showed statistically higher mean values of MRCP positive potential than the concentric contraction group. Conclusion: Researching a cerebral cortex activity, using MRCP, would provide basic data for clinical neuro-physiological researches on aging or neural plasticity of patients with a central nervous system injury.

• Korean Journal of Mathematics
• /
• v.31 no.3
• /
• pp.373-383
• /
• 2023

The aim of this paper is to prove some new approximate best proximity pair theorems on metric spaces using contraction mappings such as P-Bianchini contraction, P - B contraction and so on. A few examples are provided to exemplify our findings. Finally, we discuss some applications that are related to the main results.

• The Korean Journal of Physiology and Pharmacology
• /
• v.17 no.2
• /
• pp.139-147
• /
• 2013

Lysolipids such as LPA, S1P and SPC have diverse biological activities including cell proliferation, differentiation, and migration. We investigated signaling pathways of LPA-induced contraction in feline esophageal smooth muscle cells. We used freshly isolated smooth muscle cells and permeabilized cells from cat esophagus to measure the length of cells. Maximal contraction occurred at $10^{-6}M$ and the response peaked at 30s. To identify LPA receptor subtypes in cells, western blot analysis was performed with antibodies to LPA receptor subtypes. LPA1 and LPA3 receptor were detected at 50 kDa and 44 kDa. LPA-induced contraction was almost completely blocked by LPA receptor (1/3) antagonist KI16425. Pertussis toxin (PTX) inhibited the contraction induced by LPA, suggesting that the contraction is mediated by a PTX-sensitive G protein. Phospholipase C (PLC) inhibitors U73122 and neomycin, and protein kinase C (PKC) inhibitor GF109203X also reduced the contraction. The PKC-mediated contraction may be isozyme-specific since only $PKC{\varepsilon}$ antibody inhibited the contraction. MEK inhibitor PD98059 and JNK inhibitor SP600125 blocked the contraction. However, there is no synergistic effect of PKC and MAPK on the LPA-induced contraction. In addition, RhoA inhibitor C3 exoenzyme and ROCK inhibitor Y27632 significantly, but not completely, reduced the contraction. The present study demonstrated that LPA-induced contraction seems to be mediated by LPA receptors (1/3), coupled to PTX-sensitive G protein, resulting in activation of PLC, PKC-${\varepsilon}$ pathway, which subsequently mediates activation of ERK and JNK. The data also suggest that RhoA/ROCK are involved in the LPA-induced contraction.

• The Pure and Applied Mathematics
• /
• v.29 no.4
• /
• pp.335-352
• /
• 2022

In this paper, we give an extended version of fixed point results for 𝜃-contraction and 𝜃-𝜙-contraction and define a new type of contraction, namely, cyclic 𝜃-contraction and cyclic 𝜃-𝜙-contraction in a complete metric space. Moreover, we prove the existence of best proximity point for cyclic 𝜃-contraction and cyclic 𝜃-𝜙-contraction. Also, we establish best proximity result in the setting of uniformly convex Banach space.

• Nonlinear Functional Analysis and Applications
• /
• v.29 no.2
• /
• pp.461-475
• /
• 2024

The concept of an extension α-F-contraction and it's modified counterpart represents an advancement in the theory of metric space contractions. Through our study of the contraction principles and it's relationship to extension and modified extension, we found different conditions somewhat lengthy. In our paper, we create a development of the conditions for the extension of α-F-contraction and a modified α-F-contraction by reducing the conditions and make them easier. Our propose conditions are notably simple and effective. They serve as the foundation for proving theorems and solving examples that belong to our study. Moreover, they have remarkable significance in the condition of mathematical analysis and problem-solving. Thus, we find that these new conditions that we mention in the definitions achieve what is require and through them, we choose λ = 1 and we choose λ ∈ (0, 1) to clarify our ideas.

• Journal of the Korean Society of Physical Medicine
• /
• v.6 no.3
• /
• pp.287-292
• /
• 2011

Purpose :The present study invesigated the effect of changes in transversus abdominis thickness using ultrasonography during a hip adductor contraction. Methods : This study was carred out in a volunteer sample of adults (N=30) without a history of low back pain or injury. In standing position, muscle thickness measurements of transversus abdominis(TrA) were measured using ultrasonography at rest and during a hip adducor contraction. Results : TrA thickness were influenced a hip adductor during a voluntary contraction in people without LBP. TrA showed significantly greater thickness changes on a hip adductor contraction.(p=0.000) Conclusion : The results from this study showed that the hip adductor contraction improves the ability to increase change in TrA thickness. These results can be a good evidence to prevent low back pain due to hip adductor weakness or genu varum deformity of knee osteoarthritis.

• PNF and Movement
• /
• v.14 no.1
• /
• pp.59-65
• /
• 2016

Purpose: The purpose of this study was to review articles in order to establish optimal contraction intensity and duration in the performance of relaxation techniques for maximal increase in range of motion. Methods: The Cochrane, EBSCO, Embase, Medline, ProQuest, PubMed, ScienceDirect, and Scopus databases were used to search articles from 1990 to January 2016. The search terms were "contract relax," "hold relax," "muscle energy technique (MET)," and "proprioceptive neuromuscular facilitation (PNF) stretching." Only experimental human studies (randomized controlled trials) that compared the effects of varying intensity and duration of isometric contraction were included. Non-English language and unpublished studies were excluded. Results: A total of 2,156 articles were initially identified, with only five eventually meeting the inclusion and exclusion criteria. Three studies compared the effects of varying intensity in isometric contraction and two studies compared the effects of varying duration in isometric contraction with regard to range of motion (ROM). Two articles suggested that submaximal voluntary isometric contraction was more effective than maximum voluntary isometric contraction (MVIC) in the improvement of ROM. One article showed that a longer contraction time led to greater increases in ROM. Conclusion: Submaximal voluntary isometric contraction was recommended during contract-relax exercises in healthy people. Lack of evidence makes it difficult to suggest the optimal duration of isometric contraction during relaxation techniques. For future research, high-quality evidence will be needed to establish the optimal contraction intensity for maximum improvement of ROM.

• The Journal of Korean Physical Therapy
• /
• v.35 no.2
• /
• pp.43-47
• /
• 2023

Purpose: This study compared the movement control ability of the ankle joint according to the type of muscle contraction, namely, eccentric or concentric contractions. Methods: Thirty-four healthy adult subjects participated in this study. As a single group, before the experiment, the subjects were trained on achieving the required position of the ankle around the target point by manually controlling the ankle dorsiflexion by 10°. Concentric contraction starts at 0° and continues until the target point of 10° is reached. During an eccentric contraction, the ankle joint starts at 20° ankle dorsiflexion and continues till the target point is reached. Movements using eccentric contraction and concentric contraction were randomly performed 3 times each. Results: The results of comparing the difference in the movement control ability of each type of muscle contraction of ankle dorsiflexion showed that the measurement-remeasurement error was significant in eccentric contraction. Conclusion: In this study, we found a difference in the ability to control movement according to whether the contraction is eccentric or concentric. Therefore, we propose that the ability to control movement is affected by the type of muscle contraction.