Microlymphatic and tissue oxygen tension in the rat mesentery

1 Department of Bioengineering, University of California-San Diego, La Jolla, California 92093; and 2 Department of Mechanical Engineering, Universidad de los Andes, Bogotá, Colombia Submitted 25 September 2003 ; accepted in final form 12 November 2003 Oxygen phosphorescence quenching was used to measure tissue P O 2 of lymphatic vessels of 43.6 ± 23.1 µm (mean ± SD) diameter in tissue locations of the rat mesentery classified according to anatomic location. Lymph and adipose tissue P O 2 were 20.6 ± 9.1 and 34.1 ± 7.8 mmHg, respectively, with the difference being statistically significant. Rare microlymphatic vessels in connective tissue not surrounded by microvessels had a P O 2 of 0.8 ± 0.2 mmHg, whereas the surrounding tissue P O 2 was 3.0 ± 3.2 mmHg, with both values being significantly lower than those of adipose tissue. Lower of lymph fluid P O 2 relative to the surrounding tissue was also evident in paired measurements of P O 2 in the lymphatic vessels and perilymphatic adipose tissue, which was significantly lower than the P O 2 in paired adipose tissue. The P O 2 of the lymphatic fluid of the mesenteric microlymphatics is consistently lower than that of the surrounding adipose tissue by 11 mmHg; therefore, lymph fluid has the lowest P O 2 of this tissue. The disparity between lymph and tissue P O 2 is attributed to the microlymphatic vessel wall and lymphocyte oxygen consumption. lymph oxygen; lymphatic wall; oxygen consumption Address for reprint requests and other correspondence: N. Hangai-Hoger, Dept. of Bioengineering, 0412, Univ. of California-San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0412 (E-mail: nhangai{at}bioeng.ucsd.edu ).