Effects of bradykinin on lymphatic pumping in the rat
mesentery.
Yokoyama, Shin, and Joseph N. Benoit.
Department of Physiology and Biophysics, Louisiana State University
Medical Center, Shreveport, Louisiana, 71130 and Department of
Physiology, University of South Alabama, College of Medicine, Mobile,
Alabama 36688
APStracts 2:0221G, 1995.
The effects of bradykinin on lymphatic pump activity of rat mesenteric
collecting duct were studied and the receptor subtype responsible for
the bradykinin response evaluated. Rats were anesthetized with
intraperitoneal (-chloralose and urethane, and exteriorized
mesenteries were studied using intravital microscopic techniques. The
diameter of the collecting lymph vessels (approximately 100 m) were
continuously monitored and lymphatic pump parameters (end diastolic
diameter, end systolic diameter, stroke volume index, ejection
fraction, contraction frequency, and pump flow index) were
calculated. Bradykinin (0.1 nM - 1.0 nM) did not affect end diastolic
diameter, end systolic diameter, stroke volume index, and ejection
fraction. Bradykinin increased lymphatic contraction frequency and
pump flow index in a dose-dependent manner. [Leu8]-desArg9-bradykinin
(B1 antagonist, 0.1 M) had no effect on baseline lymphatic pumping
but completely inhibited the bradykinin-induced increase in
contraction frequency. N-acetyl-D-Arg-[Hyp3,Thi5,8,D-Phe7]-bradykinin
(B2 antagonist, 0.1 M) significantly depressed lymphatic contraction
frequency in baseline conditions but had no effect on bradykinin
-induced increases in contraction frequency. These results indicate
that bradykinin induces positive chronotropic but not inotropic
effects on lymphatic pump activity through the stimulation of B1
-receptors.
Received 22 May 1995; accepted in final form 16 October 1995.
APS Manuscript Number G218-5.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 November 95