scholarly journals A multiscale sliding filament model of lymphatic muscle pumping

2021 ◽  
Author(s):  
Christopher J. Morris ◽  
David C. Zawieja ◽  
James E. Moore
Keyword(s):  
Smooth Muscle ◽  
Interstitial Fluid ◽  
Cellular Level ◽  
Calcium Oscillations ◽  
Lumped Parameter Model ◽  
Maximum Efficiency ◽  
Lumped Parameter ◽  
Muscle Types ◽  
Lymphatic Pumping ◽  
The Relationship

AbstractThe lymphatics maintain fluid balance by returning interstitial fluid to veins via contraction/compression of vessel segments with check valves. Disruption of lymphatic pumping can result in a condition called lymphedema with interstitial fluid accumulation. Lymphedema treatments are often ineffective, which is partially attributable to insufficient understanding of specialized lymphatic muscle lining the vessels. This muscle exhibits cardiac-like phasic contractions and smooth muscle-like tonic contractions to generate and regulate flow. To understand the relationship between this sub-cellular contractile machinery and organ-level pumping, we have developed a multiscale computational model of phasic and tonic contractions in lymphatic muscle and coupled it to a lymphangion pumping model. Our model uses the sliding filament model (Huxley in Prog Biophys Biophys Chem 7:255–318, 1957) and its adaptation for smooth muscle (Mijailovich in Biophys J 79(5):2667–2681, 2000). Multiple structural arrangements of contractile components and viscoelastic elements were trialed but only one provided physiologic results. We then coupled this model with our previous lumped parameter model of the lymphangion to relate results to experiments. We show that the model produces similar pressure, diameter, and flow tracings to experiments on rat mesenteric lymphatics. This model provides the first estimates of lymphatic muscle contraction energetics and the ability to assess the potential effects of sub-cellular level phenomena such as calcium oscillations on lymphangion outflow. The maximum efficiency value predicted (40%) is at the upper end of estimates for other muscle types. Spontaneous calcium oscillations during diastole were found to increase outflow up to approximately 50% in the range of frequencies and amplitudes tested.

scholarly journals The relationship between lymphangion chain length and maximum pressure generation established through in vivo imaging and computational modeling

2017 ◽  
Vol 313 (6) ◽  
pp. H1249-H1260 ◽  
Author(s):  
Mohammad S. Razavi ◽  
Tyler S. Nelson ◽  
Zhanna Nepiyushchikh ◽  
Rudolph L. Gleason ◽  
J. Brandon Dixon
Keyword(s):  
Nitric Oxide ◽  
Smooth Muscle ◽  
Minimally Invasive ◽  
Chain Length ◽  
Maximum Pressure ◽  
Computational Simulations ◽  
A Chain ◽  
Lymphatic Pumping ◽  
The Relationship

The intrinsic contraction of collecting lymphatic vessels serves as a pumping system to propel lymph against hydrostatic pressure gradients as it returns interstitial fluid to the venous circulation. In the present study, we proposed and validated that the maximum opposing outflow pressure along a chain of lymphangions at which flow can be achieved increases with the length of chain. Using minimally invasive near-infrared imaging to measure the effective pumping pressure at various locations in the rat tail, we demonstrated increases in pumping pressure along the length of the tail. Computational simulations based on a microstructurally motivated model of a chain of lymphangions informed from biaxial testing of isolated vessels was used to provide insights into the pumping mechanisms responsible for the pressure increases observed in vivo. These models suggest that the number of lymphangions in the chain and smooth muscle cell force generation play a significant role in determining the maximum outflow pressure, whereas the frequency of contraction has no effect. In vivo administration of nitric oxide attenuated lymphatic contraction, subsequently lowering the effective pumping pressure. Computational simulations suggest that the reduction in contractile strength of smooth muscle cells in the presence of nitric oxide can account for the reductions in outflow pressure observed along the lymphangion chain in vivo. Thus, combining modeling with multiple measurements of lymphatic pumping pressure provides a method for approximating intrinsic lymphatic muscle activity noninvasively in vivo while also providing insights into factors that determine the extent that a lymphangion chain can transport fluid against an adverse pressure gradient. NEW & NOTEWORTHY Here, we report the first minimally invasive in vivo measurements of the relationship between lymphangion chain length and lymphatic pumping pressure. We also provide the first in vivo validation of lumped parameter models of lymphangion chains previously developed through data obtained from isolated vessel testing.

Parameter Sensitivity Analysis of a Lumped-Parameter Model of Lymphangions in Series

2012 ◽  
Author(s):  
Samira Jamalian ◽  
James E. Moore ◽  
Christopher D. Bertram ◽  
Will Richardson
Keyword(s):  
Sensitivity Analysis ◽  
Interstitial Fluid ◽  
Lymphatic System ◽  
Lumped Parameter Model ◽  
Node Dissection ◽  
Parameter Sensitivity Analysis ◽  
Protein Balance ◽  
Vital Functions ◽  
Lumped Parameter ◽  
In Series

The lymphatic system is responsible for vital functions in the human body. In particular, it plays an important role in the immune system mechanism whereby undesirable elements are destroyed in the lymph nodes. But cancer cells also spread via the lymphatic system. The system maintains fluid and protein balance by gathering approximately 4 L/day of interstitial fluid and returning it to the venous system. Lymphedema, an ailment of the system for which there is no known cure, primarily affects cancer patients who have undergone lymph node dissection [1]. To understand how to treat such pathologies of the lymphatic system, it is first necessary to examine its fluid flow and pumping mechanisms quantitatively.

scholarly journals The Relationship between Spontaneous Calcium Oscillations and Cell Proliferation in Cultured Smooth Muscle Cells

1994 ◽  
Vol 65 (1) ◽  
pp. 59-62
Author(s):  
Toru Kawanishi ◽  
Megumi Kawanishi ◽  
Hisayuki Ohata ◽  
Kazuhiro Toyoda ◽  
Michihito Takahashi ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Calcium Oscillations ◽  
Cultured Smooth Muscle Cells ◽  
The Relationship

Effects of Lymphangion Subdivision in a Numerical Model of a Lymphatic Vessel

2011 ◽  
Author(s):  
Christopher D. Bertram ◽  
Charles Macaskill ◽  
James E. Moore
Keyword(s):  
Smooth Muscle ◽  
Numerical Model ◽  
Lymphatic Vessel ◽  
Smooth Muscle Contraction ◽  
Lumped Parameter Model ◽  
Active Tension ◽  
Lumped Parameter ◽  
Pumping Efficiency ◽  
In Series ◽  
Passive Compression

We have recently reported development of a lumped-parameter model for several lymphangions in series [1]. The model provides for both active smooth muscle contraction (intrinsic pumping) and passive compression of the lymphatic by external tissues (extrinsic pumping). The valves which define the lymphangions vary their resistance sigmoidally, having a high (low) resistance for an adverse (favorable) pressure difference. With no refractory period between sinusoidal active tension episodes, maximum pumping efficiency was reached when each lymphangion contracted 135° after that immediately upstream; simultaneous contraction (corresponding to the situation of extrinsic pumping) was especially inefficient.

Analysis of a High-Speed Solenoid-Actuated Mechanism

1968 ◽  
Vol 90 (3) ◽  
pp. 441-448 ◽  
Author(s):  
R. L. Wirth
Keyword(s):  
Mechanical System ◽  
High Speed ◽  
Lumped Parameter Model ◽  
Electromagnetic System ◽  
Motion Equations ◽  
Lumped Parameter ◽  
Intermittent Contact ◽  
Impressed Current ◽  
Systematic Solution ◽  
The Relationship

The mechanism which is considered in this paper is a high-speed, solenoid-driven, impact printing mechanism. The purpose of the analysis is to construct a mathematical model of the mechanism from which the dynamics of the mechanism can be studied during a complete printing cycle. The basic approach taken is to construct a lumped parameter model of the mechanical system. Motion equations are written which are solved simultaneously with equations governing the electromagnetic system. Elements of the mechanical system which are described include viscoelastic buffers between impacting parts. Dead space or intermittent contact between parts is another aspect of the problem which is defined. The relationship between core flux and impressed current is established through an experimentally measured magnetization curve. Equations governing both the rise and fall of the magnetic flux are developed since a complete cycle of operation is under study. The resulting set of equations is nonlinear in nature and impractical to solve by hand. However, a systematic solution to the equations is readily obtained by numerical integration on a digital computer.

scholarly journals The Relationship between Spontaneous Calcium Oscillations and Cell Proliferation in Cultured Smooth Muscle Cells.

1994 ◽  
Vol 65 (1) ◽  
pp. 59-62 ◽  
Author(s):  
Toru Kawanishi ◽  
Megumi Kawanishi ◽  
Hisayuki Ohata ◽  
Kazuhiro Toyoda ◽  
Michihito Takahashi ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Calcium Oscillations ◽  
Cultured Smooth Muscle Cells ◽  
The Relationship

A Novel Design of a Self-Sensing Compensating Restrictor/Pad Module for Hydrostatic Bearings

2014 ◽  
Author(s):  
Cho-Yun Yang ◽  
Cho-Yu Yang ◽  
Jia-Wei Lu ◽  
Wei-Chih Lee ◽  
Yu-Min Hung ◽  
...  
Keyword(s):  
Carrying Capacity ◽  
Pressure Ratio ◽  
Lumped Parameter Model ◽  
Design Parameters ◽  
Load Carrying Capacity ◽  
Hydrostatic Bearings ◽  
Lumped Parameter ◽  
Load Carrying ◽  
Membrane Type ◽  
The Relationship

This paper proposes the design of a self-sensing compensating restrictor/pad module for hydrostatic bearings. The module consists of a bearing pad and the associated restrictor featuring the characteristics of self-sensing compensation and easy installation. The paper first introduces the configuration of the proposed module. Then, the lumped parameter model was used to derive the equation for the relationship between the pocket pressure and the bearing gap. Furthermore, equations governing the stiffness and load-carrying capacity of the bearing were also obtained. Influences of the design parameters, such as the land length and pressure ratio, on bearing performance and the feasibility of the new design were studied both analytically and experimentally. Results of the theoretical analysis were compared with that of the experiment. Superior performances on the aspects of stiffness and load-carrying capacity, as well as time delay due to the distance between restrictor and bearing pad to the traditional restrictors such as capillary and orifice were achieved. In addition, the proposed restrictor possesses the advantages of simplicity for both manufacturing and assembly in comparison with the membrane-type restrictors.

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