Human thoracic duct in vitro: diameter-tension properties, spontaneous and evoked contractile activity.
The current study characterizes the mechanical properties of the human thoracic duct and demonstrates a role for adrenoceptors, thromboxane, and endothelin receptors in human lymph vessel function. With ethical permission and informed consent, portions of the thoracic duct (2-5 cm) were resected and retrieved at T(7)-T(9) during esophageal and cardia cancer surgery. Ring segments (2 mm long) were mounted in a myograph for isometric tension (N/m) measurement. The diameter-tension relationship was established using ducts from 10 individuals. Peak active tension of 6.24 +/- 0.75 N/m was observed with a corresponding passive tension of 3.11 +/- 0.67 N/m and average internal diameter of 2.21 mm. The equivalent active and passive transmural pressures by LaPlace's law were 47.3 +/- 4.7 and 20.6 +/- 3.2 mmHg, respectively. Subsequently, pharmacology was performed on rings from 15 ducts that were normalized by stretching them until an equivalent pressure of 21 mmHg was calculable from the wall tension. At low concentrations, norepinephrine, endothelin-1, and the thromboxane-A(2) analog U-46619 evoked phasic contractions (analogous to lymphatic pumping), whereas at higher contractions they induced tonic activity (maximum tension values of 4.46 +/- 0.63, 5.90 +/- 1.4, and 6.78 +/- 1.4 N/m, respectively). Spontaneous activity was observed in 44% of ducts while 51% of all the segments produced phasic contractions after agonist application. Acetylcholine and bradykinin relaxed norepinephrine preconstrictions by approximately 20% and approximately 40%, respectively. These results demonstrate that the human thoracic duct can develop wall tensions that permit contractility to be maintained across a wide range of transmural pressures and that isolated ducts contract in response to important vasoactive agents.
Telinius
Niklas
N
Dept. of Physiology and Biophysics, Aarhus Univ., Ole Worms Allé 4, Universitetsparken, DK-8000 Arhus C, Denmark. telinius@me.com
Drewsen
Nanna
N
Pilegaard
Hans
H
Kold-Petersen
Henrik
H
de Leval
Marc
M
Aalkjaer
Christian
C
Hjortdal
Vibeke
V
Boedtkjer
Donna Briggs
DB
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D000109:Acetylcholine / Q000494:pharmacology; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D019332:Endothelin-1 / Q000494:pharmacology; D006801:Humans; D007537:Isometric Contraction / Q000187:drug effects / Q000502:physiology*; D009213:Myography; D009638:Norepinephrine / Q000494:pharmacology; D011941:Receptors, Adrenergic / Q000378:metabolism*; D013897:Thoracic Duct / Q000187:drug effects / Q000502:physiology*; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology
D000316:Adrenergic alpha-Agonists; D019332:Endothelin-1; D011941:Receptors, Adrenergic; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000109:Acetylcholine; D009638:Norepinephrine