Journal of Dental Research, Vol 80, 1995-1999, Copyright © 2001 by International & American Associations for Dental Research Online Journals
Acetylcholine-induced vasodilation of isolated pulpal arterioles
C. Y. Yu, N. M. Boyd, S. J. Cringle, E. N. Su, V. A. Alder and D. Y. Yu
School of Dentistry, The University of Western Australia, Perth, Australia. chrisyu@cyllene.uwa.edu.au
The presence of cholinergic mechanisms in the control of pulpal
microcirculation has been a controversial issue. In this study, we aimed to
determine the direct vasoactive responses of isolated pulpal arterioles to
acetylcholine, and to investigate whether such responses are
endothelium-dependent. Using an in vitro micro-perfusion system, we
isolated pig pulpal arterioles, cannulated and perfused them
intraluminally, and monitored the diameter. Following equilibration, the
vessels were contracted with 10(-5) M noradrenaline, and the effect of
increasing doses of acetylcholine was determined. The influence of the
muscarinic antagonist, atropine, or the loss of endothelial cell function
following saponin treatment was also determined. Acetylcholine induced a
dose-dependent vasodilation, reaching 94.6+/-1.4% (n = 22) of the
uncontracted diameter at 10(-4) M. The vascular relaxation effect of
acetylcholine was abolished in the presence of atropine, and by saponin
treatment. Analysis of these data suggests that, in the pig, the
acetylcholine-induced vasodilation of incisor pulpal arterioles is
endothelium-dependent and mediated by muscarinic receptors.
