Importance of Valves and Lymphangion Contractions in Determining Pressure Gradients in Isolated Lymphatics Exposed to Elevations in Outflow Pressure

Eisenhoffer, John; Kagal, Anju; Klein, Tom; Johnston, Mary

doi:10.1006/mvre.1995.1008

Cited by 46 publications

(24 citation statements)

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“…It is commonly supposed that variations in lymphatic pressure play a significant role in interstitial drainage [15,37,39,40,55,57]. The size of such variations is typically around 100 Pa which compares to a mean pressure difference between blood and lymphatic capillaries of around 3000 Pa. At the end of §2 we noted that the steady state solution to the model depends only on lymphatic pressure P l and blood capillary pressure P b through their difference P b − P l .…”

Section: Discussionmentioning

confidence: 76%

“…The lumen pressure in the primary lymphatic system fluctuates as a consequence of pressure variations in the secondary lymphatic system [15,55,57]. In order to investigate these fluctuations in lymphatic lumen pressure we apply a periodic lymphatic pressure P l , after the system has been allowed to equilibriate, and investigate its effects on primary lymphatic drainage.…”

Section: Fluctuation To the Lymphatic Lumen Pressurementioning

confidence: 99%

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A Model for Interstitial Drainage Through a Sliding Lymphatic Valve

2015

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This study investigates fluid flow and elastic deformation in tissues that are drained by the primary lymphatic system. A model is formulated based on the Rossi hypothesis that states that the primary lymphatic valves, which are formed by overlapping endothelial cells around the circumferential lining of lymphatic capillaries, open in response to swelling of the surrounding tissue. Tissue deformation and interstitial fluid flow through the tissue are treated using the Biot equations of poroelasticity and, the fluid flux, (into the interstitium) across the walls of the blood capillaries, is assumed to be linearly related to the pressure difference across the walls via a constant of proportionality (the vascular permeability). The resulting model is solved in a periodic domain containing one blood capillary and one lymphatic capillary starting from a configuration in which the tissue is undeformed. On imposition of a constant pressure difference between blood and lymphatic capillaries the solutions are found to settle to a steady state. Given that the magnitude of pressure fluctuations in the lymphatic system is much smaller than this pressure difference between blood and lymph it is postulated that the resulting steady state solution gives a good representation of the state of the tissue under physiological conditions. The effects of changes to the Young's modulus of the tissue, the blood-lymphatic pressure difference, vascular permeability and valve dimensions on the steady state are investigated and discussed in terms of their effects on oedema in the context of age-and pregnancy-related changes to the body.

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Section: Discussionmentioning

confidence: 76%

Section: Fluctuation To the Lymphatic Lumen Pressurementioning

confidence: 99%

A Model for Interstitial Drainage Through a Sliding Lymphatic Valve

2015

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“…[24][25][26][27][28][29][30][31] These important structures are a hallmark of the lymphatic network and their proper function depends upon some unique properties of the lymphatic. 24,26,29,30,32,33 The function of the lymphatic valves is thought to be driven by the pressures and flow of fluid across them, given their unique structure.…”

Section: The Secondary Lymphatic Valve Systemmentioning

confidence: 99%

Contractile Physiology of Lymphatics

Zawieja¹

2009

Lymphatic Research and Biology

299

307

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“…Previous studies using isolated chains of series-coupled lymphatic segments from several species have provided evidence that lymphatic vessels are exquisitely sensitive to changes in filling pressure and accordingly modulate pump output using the Frank-Starling mechanism (13,15,26,28). Notably, two studies have made use of cardiac-style analyses to study lymphatic pump function.…”

mentioning

confidence: 99%

Independent and interactive effects of preload and afterload on the pump function of the isolated lymphangion

Scallan

Wolpers

Muthuchamy³

et al. 2012

American Journal of Physiology-Heart and Circulatory Physiology

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Scallan JP, Wolpers JH, Muthuchamy M, Zawieja DC, Gashev AA, Davis MJ. Independent and interactive effects of preload and afterload on the pump function of the isolated lymphangion. Am J Physiol Heart Circ Physiol 303: H809 -H824, 2012. First published August 3, 2012; doi:10.1152/ajpheart.01098.2011We tested the responses of single, isolated lymphangions to selective changes in preload and the effects of changing preload on the response to an imposed afterload. The methods used were similar to those described in our companion paper.Step-wise increases in input pressure (Pin; preload) over a pressure range between 0.5 and 3 cmH2O, at constant output pressure (Pout), led to increases in end-diastolic diameter, decreases in endsystolic diameter, and increases in stroke volume. From a baseline of 1 cmH 2O, Pin elevation by 2-7 cmH2O consistently produced an immediate fall in stroke volume that subsequently recovered over a time course of 2-3 min. Surprisingly, this adaptation was associated with an increase in the slope of the end-systolic pressure-volume relationship, indicative of an increase in contractility. Lymphangions subjected to Pout levels exceeding their initial ejection limit would often accommodate by increasing diastolic filling to strengthen contraction sufficiently to match Pout. The lymphangion adaptation to various pressure combinations (Pin ramps with low or high levels of Pout, Pout ramps at low or intermediate levels of Pin, and combined Pin ϩ Pout ramps) were analyzed using pressure-volume data to calculate stroke work. Under relatively low imposed loads, stroke work was maximal at low preloads (Pin ϳ2 cmH2O), whereas at more elevated afterloads, the optimal preload for maximal work displayed a broad plateau over a Pin range of 5-11 cmH2O. These results provide new insights into the normal operation of the lymphatic pump, its comparison with the cardiac pump, and its potential capacity to adapt to increased loads during edemagenic and/or gravitational stress. pressure-volume loop; isolated vessel; edema; heterometric regulation; homeometric regulation; stroke work; contractility IN OUR COMPANION PAPER (10), we investigated the effects of selective afterload elevation on the pump function of single lymphangions isolated from the rat mesentery. Elevating output pressure (P out ), at constant preload [input pressure (P in )], led to an intrinsic increase in lymphatic muscle contractility (i.e., positive inotropy), as characterized by a leftward shift in the end systolic pressure-volume relationship (ESPVR), increased peak dP/dt, and the development of higher peak systolic pressure. We concluded that the enhancement in contractility enables the vessel to eject against the adverse pressure gradient that normally exists in most parts of the lymphatic system and that becomes substantially elevated in lymphatic vessels of dependent extremities, including those of humans (31).As in the heart, preload is a significant determinant of lymphatic pump function. Previous studies using isolated chains of seri...

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Importance of Valves and Lymphangion Contractions in Determining Pressure Gradients in Isolated Lymphatics Exposed to Elevations in Outflow Pressure

Cited by 46 publications

References 0 publications

A Model for Interstitial Drainage Through a Sliding Lymphatic Valve

A Model for Interstitial Drainage Through a Sliding Lymphatic Valve

Contractile Physiology of Lymphatics

Independent and interactive effects of preload and afterload on the pump function of the isolated lymphangion

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