scholarly journals A myofibre model for the study of uterine excitation-contraction dynamics

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Uri Goldsztejn ◽  
Arye Nehorai
Keyword(s):  
Uterine Contraction ◽  
Muscle Layer ◽  
Tissue Level ◽  
Intercellular Coupling ◽  
Force Development ◽  
Uterine Contractions ◽  
Cellular Excitability ◽  
Slow Progress ◽  
Contraction Dynamics ◽  
Electrical Propagation

Abstract As the uterus remodels in preparation for delivery, the excitability and contractility of the uterine smooth muscle layer, the myometrium, increase drastically. But when remodelling proceeds abnormally it can contribute to preterm birth, slow progress of labour, and failure to initiate labour. Remodelling increases intercellular coupling and cellular excitability, which are the main targets of pharmaceutical treatments for uterine contraction disorders. However, the way in which electrical propagation and force development depend on intercellular coupling and cellular excitability is not fully understood. Using a computational myofibre model we study the dependency of electrical propagation and force development on intercellular coupling and cellular excitability. This model reveals that intercellular coupling determines the conduction velocity. Moreover, our model shows that intercellular coupling alone does not regulate force development. Further, cellular excitability controls whether conduction across the cells is blocked. Lastly, our model describes how cellular excitability regulates force development. Our results bridge cellular factors, targeted by drugs to regulate uterine contractions, and tissue level electromechanical properties, which are responsible for delivery. They are a step forward towards understanding uterine excitation-contraction dynamics and developing safer and more efficient pharmaceutical treatments for uterine contraction disorders.

scholarly journals Existence of Galanin in Lumbosacral Sympathetic Ganglionic Neurons That Project to the Quail Uterine Oviduct*

Endocrinology ◽  
2000 ◽  
Vol 141 (12) ◽  
pp. 4402-4412 ◽  
Author(s):  
Hirotaka Sakamoto ◽  
Takayoshi Ubuka ◽  
Chie Kohchi ◽  
Dan Li ◽  
Kazuyoshi Ukena ◽  
...  
Keyword(s):  
Messenger Rna ◽  
Uterine Contraction ◽  
Northern Blot Analysis ◽  
Neurosecretory Cell ◽  
Muscle Layer ◽  
Enzyme Linked Immunosorbent Assay ◽  
Retrograde Labeling ◽  
Uterine Contractions ◽  
Uterine Muscle ◽  
Japanese Quails

Abstract Oviposition in birds is conducted by vigorous contractions of the uterine oviduct. We recently isolated an oviposition-inducing peptide that was identified as avian galanin from mature quail oviducts. This peptide was localized in neuronal fibers terminating in muscle layers in the uterine oviduct and evoked vigorous uterine contractions through binding to receptors located in the uterus. However, no cell bodies that express avian galanin were detected in the uterus or other oviduct regions. To understand the control mechanism of avian oviposition by galanin, we identified the neurons that synthesize galanin and project to the uterus with the combination of retrograde labeling with neurobiotin and immunocytochemistry for galanin in mature Japanese quails. Retrograde labeling with neurobiotin from the uterus revealed that lumbosacral sympathetic ganglionic neurons located in the uterine side projected their axons to the uterine muscle layer. Abundant elementary granules were observed in somata of the retrogradely labeled sympathetic ganglionic neurons, suggesting that labeled neurons may function as a neurosecretory cell. Immunocytochemical analysis with the antiserum against avian galanin showed an intense immunoreaction restricted to somata of the retrograde-labeled ganglionic neurons. Preabsorbing the antiserum with avian galanin resulted in a complete absence of the immunoreaction. Competitive enzyme-linked immunosorbent assay using antigalanin serum confirmed that avian galanin existed in the sympathetic ganglionic neurons. Expression of the avian galanin messenger RNA in the neurons was further verified by Northern blot analysis. In addition, both avian galanin and its messenger RNA in the neurons were highly expressed in mature birds, unlike in immature birds. These results suggest that lumbosacral sympathetic ganglionic neurons innervating the uterine muscle produce avian galanin in mature birds. Because this peptide acts directly on the uterus to evoke oviposition through a mechanism of the induction of vigorous uterine contraction, galaninergic innervation of the uterine oviduct may be essential for avian oviposition.

scholarly journals Fractional diffusion models of cardiac electrical propagation: role of structural heterogeneity in dispersion of repolarization

2014 ◽  
Vol 11 (97) ◽  
pp. 20140352 ◽  
Author(s):  
Alfonso Bueno-Orovio ◽  
David Kay ◽  
Vicente Grau ◽  
Blanca Rodriguez ◽  
Kevin Burrage
Keyword(s):  
Structural Heterogeneity ◽  
Biological Tissues ◽  
Tissue Level ◽  
Fractional Diffusion ◽  
Diffusion Models ◽  
Excitable Media ◽  
Research Fields ◽  
Dispersion Of Repolarization ◽  
Electrical Propagation

Impulse propagation in biological tissues is known to be modulated by structural heterogeneity. In cardiac muscle, improved understanding on how this heterogeneity influences electrical spread is key to advancing our interpretation of dispersion of repolarization. We propose fractional diffusion models as a novel mathematical description of structurally heterogeneous excitable media, as a means of representing the modulation of the total electric field by the secondary electrical sources associated with tissue inhomogeneities. Our results, analysed against in vivo human recordings and experimental data of different animal species, indicate that structural heterogeneity underlies relevant characteristics of cardiac electrical propagation at tissue level. These include conduction effects on action potential (AP) morphology, the shortening of AP duration along the activation pathway and the progressive modulation by premature beats of spatial patterns of dispersion of repolarization. The proposed approach may also have important implications in other research fields involving excitable complex media.

scholarly journals PRETERM LABOUR

2010 ◽  
Vol 17 (01) ◽  
pp. 84-90
Author(s):  
FARZANA LATIF ◽  
BUSHRA BANO ◽  
UZMA HUSSAIN
Keyword(s):  
Glyceryl Trinitrate ◽  
Uterine Contraction ◽  
Preterm Labour ◽  
Descriptive Study ◽  
Transdermal Patch ◽  
Uterine Contractions ◽  
Non Invasive ◽  
The Mean ◽  
Study Setting ◽  
Made In

Objective: To compare the efficacy of Glyecryl trinitrate patch for prolonging gestation for more than 48 hours, 7 days or upto 37 weeks of gestation with Salbutamol in preterm labour. Study Design: Compartive descriptive study. Setting: Fatima Memorial HospitalLahore. Period: Dec 2003 to Jan 2005. Patients & Methods: The study was carried out on 60 pregnant patients admitted in hospital with thesymptoms and signs of preterm labour. The results were statistically analyzed using SPSS version 8.0. Results: Two groups (TransdermalGlyceryl Trinitrate group and Salbutamol) comprising 30 patients each were made. In Glyceryl Trinitrate group, transdermal patch was appliedand in Salbutamol group,. Intravenous infusion titrated according to frequency, duration and intensity of uterine contractions. All the patientsin each group were evaluated for prolongation of gestation for 48 hours till 37th week of gestation. The mean prolongation of pregnancy was26 days in GTN group and 32 days in Salbutamol group. The decrease in frequency of uterine contractions by 67.51 ± 7.74% in first 48 hoursof applying transdermal Glyceryl Trinitrate patch and by 80.14 ± 8.43 % in Salbutamol group which was statistically significant. Conclusion:Trinitrate appears to be a safe, well tolerated and non-invasive but less effectives method of suppressing uterine contraction in preterm labouras compared to Salbutamol.

scholarly journals Non-ohmic tissue conduction in cardiac electrophysiology: upscaling the non-linear voltage-dependent conductance of gap junctions

2019 ◽  
Author(s):  
Daniel E. Hurtado ◽  
Javiera Jilberto ◽  
Grigory Panasenko
Keyword(s):  
Computational Complexity ◽  
Gap Junctions ◽  
Cardiac Tissue ◽  
Tissue Level ◽  
Cardiac Conduction ◽  
Non Linear ◽  
Voltage Dependent ◽  
Junctional Coupling ◽  
Organ Level ◽  
Electrical Propagation

AbstractGap junctions are key mediators of the intercellular communication in cardiac tissue, and their function is vital to sustain normal cardiac electrical activity. Conduction through gap junctions strongly depends on the hemichannel arrangement and transjunctional voltage, rendering the intercellular conductance highly non-Ohmic. Despite this marked non-linear behavior, current tissue-level models of cardiac conduction are rooted on the assumption that gap-junctions conductance is constant (Ohmic), which results in inaccurate predictions of electrical propagation, particularly in the low junctional-coupling regime observed under pathological conditions. In this work, we present a novel non-Ohmic multiscale (NOM) model of cardiac conduction that is suitable for tissue-level simulations. Using non-linear homogenization theory, we develop a conductivity model that seamlessly upscales the voltage-dependent conductance of gap junctions, without the need of explicitly modeling gap junctions. The NOM model allows for the simulation of electrical propagation in tissue-level cardiac domains that accurately resemble that of cell-based microscopic models for a wide range of junctional coupling scenarios, recovering key conduction features at a fraction of the computational complexity. A unique feature of the NOM model is the possibility of upscaling the response of non-symmetric gap-junction conductance distributions, which result in conduction velocities that strongly depend on the direction of propagation, thus allowing to model the normal and retrograde conduction observed in certain regions of the heart. We envision that the NOM model will enable organ-level simulations that are informed by sub- and inter-cellular mechanisms, delivering an accurate and predictive in-silico tool for understanding the heart function.Author summaryThe heart relies on the propagation of electrical impulses that are mediated gap junctions, whose conduction properties vary depending on the transjunctional voltage. Despite this non-linear feature, current mathematical models assume that cardiac tissue behaves like an Ohmic (linear) material, thus delivering inaccurate results when simulated in a computer. Here we present a novel mathematical multiscale model that explicitly includes the non-Ohmic response of gap junctions in its predictions. Our results show that the proposed model recovers important conduction features modulated by gap junctions at a fraction of the computational complexity. This contribution represents an important step towards constructing computer models of a whole heart that can predict organ-level behavior in reasonable computing times.

Increasing Maternal Blood Pressure with Ephedrine Increases Uterine Artery Blood Flow Velocity during Uterine Contraction

2002 ◽  
Vol 96 (3) ◽  
pp. 612-616 ◽  
Author(s):  
Laurent Ducros ◽  
Philippe Bonnin ◽  
Bernard P. Cholley ◽  
Eric Vicaut ◽  
Moncef Benayed ◽  
...  
Keyword(s):  
Blood Flow ◽  
Flow Velocity ◽  
Uterine Artery ◽  
Uterine Contraction ◽  
Perfusion Pressure ◽  
Resistance Index ◽  
Hemodynamic Parameters ◽  
Uterine Blood Flow ◽  
Uterine Contractions ◽  
Uterine Perfusion

Background During labor, ephedrine is widely used to prevent or to treat maternal arterial hypotension and restore uterine perfusion pressure to avoid intrapartum fetal asphyxia. However, the effects of ephedrine on uterine blood flow have not been studied during uterine contractions. The purpose of the study was to assess the effects of ephedrine on uterine artery velocities and resistance index using the Doppler technique during the active phase of labor. Methods Ten normotensive, healthy parturients with uncomplicated pregnancies at term received intravenous ephedrine during labor to increase mean arterial pressure up to a maximum of 20% above their baseline pressure. Peak systolic and end-diastolic Doppler flow velocities and resistance indices were measured in the uterine artery before and immediately after administration of bolus intravenous ephedrine and after ephedrine washout. Umbilical and fetal middle cerebral arterial resistance indices and fetal heart rate were also calculated. Results After ephedrine administration, mean arterial pressure increased by 17 +/- 4%. End-diastolic flow velocity in the uterine artery at peak amplitude of uterine contraction was restored to 74% of the value observed in the absence of contraction. The systolic velocity was totally restored, and the uterine resistance index was significantly decreased, compared with the values in the absence of contraction. Between uterine contractions, ephedrine induced similar but less marked effects. Fetal hemodynamic parameters were not altered by ephedrine administration. Conclusions Bolus administration of intravenous ephedrine reversed the dramatic decrease in diastolic uteroplacental blood flow velocity and the increase in resistance index during uterine contraction, without altering fetal hemodynamic parameters. This suggests that the increase in uterine perfusion pressure during labor could in part restore uterine blood flow to the placenta during uterine contraction.

scholarly journals Curcuma longa aqueous extract possesses tocolytic potentials

2019 ◽  
pp. 1-6
Keyword(s):  
Traditional Medicine ◽  
Aqueous Extract ◽  
Early Pregnancy ◽  
Uterine Contraction ◽  
Preterm Labour ◽  
Curcuma Longa ◽  
Organ Bath ◽  
Pregnant Rats ◽  
Uterine Activity ◽  
Uterine Contractions

Introduction: Contraction of the uterus is an important physiological phenomenon that determines the functionality of the uterus for pregnancy and abortion. Curcuma longa, a member of the ginger family (Zingiberracaeae) has been used in traditional medicine because of its various therapeutic properties. Curcuma longa is believed to be beneficial to the female reproductive system by preventing unwanted uterine activity in early pregnancy or treat preterm labour. There are however, no scientific facts verifying the effects on the uterus to support its folklore use as tocolytic agent. The aim of this study was to determine the effects of aqueous extract of Curcuma longa rhizome and its possible mechanism of action on uterine contraction. Methods: The Isolated longitudinal uterine strips were dissected from non-pregnant rats, mounted vertically in an organ bath chamber, and exposed to the aqueous extract of Curcuma longa rhizome at a concentration of 25 - 200 mg/ml. The effects of the extract at a concentration of 50 mg/ml on spontaneous and oxytocin-induced (10 nmol/L) contractions were investigated. Results: The results of the study revealed that the extract significantly (p < 0.05) inhibited both spontaneous and oxytocin-induced uterine contractions (n = 10). The extract also inhibited oxytocin-induced contraction in the absence of exogenous calcium (n = 10). Significance: The result of this research has shown that Curcurma longa extract possesses or exerts tocolytic effect that delays uterine contraction in rats and this finding justify its folklore uses in traditional medicine to prevent unwanted uterine activity in early pregnancy or treat preterm labour.

scholarly journals Accuracy and Reliability of Uterine Contraction Identification Using Abdominal Surface Electrodes

2012 ◽  
Vol 5 ◽  
pp. CMWH.S10444 ◽  
Author(s):  
Barrie Hayes-Gill ◽  
Sarmina Hassan ◽  
Fadi G. Mirza ◽  
Sophia Ommani ◽  
John Himsworth ◽  
...  
Keyword(s):  
Root Mean Square Error ◽  
Pressure Measurement ◽  
Pressure Transducer ◽  
Uterine Contraction ◽  
Mean Square ◽  
Predictive Values ◽  
Surface Electrodes ◽  
Uterine Contractions ◽  
Intrauterine Pressure ◽  
Abdominal Surface

Objective To compare the accuracy and reliability of uterine contraction identification from maternal abdominal electrohysterogram and tocodynamometer with an intrauterine pressure transducer. Methods Seventy-four term parturients had uterine contractions monitored simultaneously with electrohysterography, tocodynamometry, and intrauterine pressure measurement. Results Electrohysterography was more reliable than tocodynamometry when compared to the intrauterine method (97.1 versus 60.9 positive percent agreement; P < 0.001). The root mean square error was lower for electrohysterography than tocodynamometry in the first stage (0.88 versus 1.22 contractions/10 minutes; P < 0.001), and equivalent to tocodynamometry in the second. The positive predictive values for tocodynamometry and electrohysterography (84.1% versus 78.7%) were not significantly different, nor were the false positive rates (21.3% versus 15.9%; P = 0.052). The sensitivity of electrohysterography was superior to that of tocodynamometry (86.0 versus 73.6%; P < 0.001). Conclusion The electrohysterographic technique was more reliable and similar in accuracy to tocodynamometry in detecting intrapartum uterine contractions.

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