Phenylbiguanide does not inhibit locomotion in conscious rabbits
.
O'hagan, Kathleen P., Rebecca S. Anderson, Leonard B. Bell, Scott W.
Mittelstadt, and Philip S. Clifford.
Departments of Anesthesiology and Physiology, Medical College of
Wisconsin and VA Medical Center, Milwaukee, Wisconsin 53295
APStracts 2:0267A, 1995.
Stimulation of cardiopulmonary vagal C-fibers with phenylbiguanide
(PBG) reflexly inhibits locomotion in addition to causing depression
of blood pressure (BP), heart rate (HR) and respiration in cats and
rats. We investigated whether PBG caused somatomotor inhibition
during exercise in the rabbit, a species in which it is known that
the hemodynamic and respiratory responses to PBG are mediated by
cardiac rather than pulmonary receptors. In 8 NZW rabbits, BP, HR and
hindlimb EMG responses to 60 and 120 g/kg PBG and saline vehicle were
evaluated during 2 separate 3 min exercise bouts at 10 m/min, 0%
grade. During exercise, 60 g/kg PBG decreased BP (-274 mmHg) and HR
(-9516 b/min), but did not inhibit locomotion as suggested by the EMG
response (&1128% of pre-infusion EMG). Hemodynamic and EMG
responses to 120 g/kg PBG were similar to 60 g/kg PBG. Saline
infusion during exercise had no effect on HR, BP or locomotion
(&1148 % of pre-infusion EMG). Locomotion is not inhibited by PBG
in rabbits, which suggests that PBG-induced reflex somatomotor
inhibition observed in other species is primarily mediated by
pulmonary rather than by cardiac receptors.
Received 9 Feb 1995; accepted in final form 31 May 1995
APS Manuscript Number A0152-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 July 1995.