Ventricular sensory neurons in canine dorsal root ganglia: effects
of exogenous and endogenous adenosine and substance p.
Huang, M. H., C. Sylv[acute]en, M. Horackova, and J. A. Armour.
Department of Physiology and Biophysics, Faculty of Medicine,
Dalhousie University, Halifax, N.S. B3H 4H7, Canada, and Karolinska
Institute, Department of Medicine, Huddinge University Hospital,
Huddinge, Sweden
APStracts 2:0085R, 1995.
M.H. Huang, C. Sylv[acute]en, M. Horackova and J.A. Armour.
Ventricular sensory neurons in canine dorsal root ganglia: effects of
exogenous and endogenous adenosine and substance P. Effects elicited
by adenosine and substance P on ventricular sensory endings of 14
dorsal root ganglion afferent neurons were studied in situ in
anesthetized dogs. Sensory-field application of adenosine (1 [mu]M)
increased the activity of these neurons by 179%. Application of a
nonspecific adenosine antagonist to epicardial sensory fields
suppressed ongoing activity in all 14 neurons by 39%. Application of
an A1- or A2-adenosine-receptor antagonist suppressed activity
generated by 10 of these neurons by 44% and 59%, respectively.
Adenosine applied after A1- or A2-receptor blockade increased
activity in 10 neurons by 131% and 145%, respectively, indicating
that A1- and A2-receptor effects were not additive. Application of
substance P (1 [mu]M) to identified sensory fields increased activity
in 12 of these neurons by 169%, whereas application of a substance P
-receptor antagonist reduced activity generated by these neurons by
75%. Myocardial ischemia increased activity of 9 neurons associated
with left ventricular sensory fields by 320%, an effect that was
counteracted by the non-specific adenosine-receptor antagonist. It is
concluded that A1- and A2-adenosine receptors as well as substance P
receptors are present on ventricular epicardial sensory nerve endings
of dorsal root ganglion neurons which are tonically active during
normal states, becoming further activated during ischemia.
Received 19 September 1994; accepted in final form 26 January
1995.
APS Manuscript Number R538-4.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 April 1995.