AJP - Heart and Circulatory Physiology, Vol 259, Issue 1 42-H47, Copyright © 1990 by American Physiological Society
Effects of atrial natriuretic peptide on isolated bovine mesenteric lymph vessels
T. Ohhashi, N. Watanabe and Y. Kawai
Department of Physiology, Shinshu University School of Medicine, Matsumoto, Japan.
The mode of action of atrial natriuretic peptide (ANP) on bovine mesenteric
lymphatics was investigated by recording isometric tensions in isolated
cylindrical segments. ANP in concentrations from 5 to 30 ng/ml caused
dose-related decreases in the rhythm and amplitude of spontaneous
contractions. No tachyphylaxis was observed in the ANP-induced responses in
lymph vessels. Addition of ANP in a low concentration ranging from 3 to 100
ng/ml produced a dose-dependent relaxation in the lymphatic preparations
precontracted by 10(-7) M bradykinin. The ANP-induced relaxation was not
modified by pretreatment with 5 x 10(-7) M propranolol, 5 x 10(-7) M
atropine, 10(-6) M cimetidine, 5 x 10(-5) M aspirin, or 10(-5) M ouabain.
The mechanical rubbing of endothelial cells in the lymph vessels caused no
significant effect on the ANP-induced relaxation. The relaxation, however,
was significantly reduced by pretreatment with 10(-5) M methylene blue.
These results suggest that ANP in a low concentration seems to inhibit
lymph transport through a reduction of spontaneous contractions and a
marked relaxation of lymphatic smooth muscles in bovine mesenteric
lymphatics and that ANP may produce the relaxation through synthesis of
guanosine 3',5' cyclic monophosphate, independent of the lymphatic
endothelium.
