Effects of dynamic shear and transmural pressure on wall shear stress sensitivity in collecting lymphatic vessels.
Given the known mechanosensitivity of the lymphatic vasculature, we sought to investigate the effects of dynamic wall shear stress (WSS) on collecting lymphatic vessels while controlling for transmural pressure. Using a previously developed ex vivo lymphatic perfusion system (ELPS) capable of independently controlling both transaxial pressure gradient and average transmural pressure on an isolated lymphatic vessel, we imposed a multitude of flow conditions on rat thoracic ducts, while controlling for transmural pressure and measuring diameter changes. By gradually increasing the imposed flow through a vessel, we determined the WSS at which the vessel first shows sign of contraction inhibition, defining this point as the shear stress sensitivity of the vessel. The shear stress threshold that triggered a contractile response was significantly greater at a transmural pressure of 5 cmH2O (0.97 dyne/cm(2)) than at 3 cmH2O (0.64 dyne/cm(2)). While contraction frequency was reduced when a steady WSS was applied, this inhibition was reversed when the applied WSS oscillated, even though the mean wall shear stresses between the conditions were not significantly different. When the applied oscillatory WSS was large enough, flow itself synchronized the lymphatic contractions to the exact frequency of the applied waveform. Both transmural pressure and the rate of change of WSS have significant impacts on the contractile response of lymphatic vessels to flow. Specifically, time-varying shear stress can alter the inhibition of phasic contraction frequency and even coordinate contractions, providing evidence that dynamic shear could play an important role in the contractile function of collecting lymphatic vessels.
Parker H. Petite Institute of Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia; George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia;
Jeffrey A
JA
Kornuta
Parker H. Petite Institute of Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia; George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia;
Zhanna
Z
Nepiyushchikh
Department of Medical Physiology, Texas A&M Health Science Center College of Medicine, Temple, Texas.
Olga Y
OY
Gasheva
Parker H. Petite Institute of Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia; School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia; and.
Anish
A
Mukherjee
Department of Medical Physiology, Texas A&M Health Science Center College of Medicine, Temple, Texas.
David C
DC
Zawieja
Parker H. Petite Institute of Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia; George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia; Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia; dixon@gatech.edu.
J Brandon
JB
Dixon
D000818:Animals; D003198:Computer Simulation; D055119:Elastic Modulus / Q000502:physiology; D066298:In Vitro Techniques; D008196:Lymph / Q000502:physiology*; D042601:Lymphatic Vessels / Q000502:physiology*; D008954:Models, Biological; D011312:Pressure; D051381:Rats; D017207:Rats, Sprague-Dawley; D033081:Shear Strength / Q000502:physiology; D013314:Stress, Mechanical
endothelial cell; lymphatic; pump function; shear stress; thoracic duct