Local and conducted vasomotor responses in isolated rat cerebral
arterioles.
Dietrich, Hans H., Yasukazu Kajita, and Ralph G. Dacey.
Department of Neurosurgery, Washington University School of
Medicine, St. Louis, Missouri, 63110
APStracts 3:0085H, 1996.
We tested the hypothesis that conduction of vasomotor responses occurs
in cannulated and isolated rat cerebral penetrating arterioles. Both
at the site of stimulation (local) and 500 to 650?[mu]m distant from
it, we observed the diameter responses and time courses thereof to
pressure ejected vasoactive stimuli. Adenosine triphosphate (ATP)
locally caused an initial constriction (response onset at 0.3?s,
average diameter 85% of control at 450?ms pulse with a maximum at
1.6?s after stimulation) followed by a secondary dilation (111% at
7?s). Conducted vasodilation of 111?% was observed over a distance of
520?[mu]m. Prostaglandin (PG) F2[alpha] constricted the vessels
locally (80%) and caused conducted vasodilation (110%). For both ATP
and PGF2[alpha] the local constriction occurred simultaneously to the
conducted vasodilation. Adenosine (ADO) dilated the vessels (123%)
but produced only inconsistent conducted vasodilation. Hydrogen ions
initially constricted the vessels (88%) and then dilated them to
113%. Thus, while ATP and PGF2[alpha] are strong promoters of
conduction, ADO and hydrogen ions are not. Paradoxically, ATP and
PGF2[alpha] caused conducted vasodilation while the initial local
response was a vasoconstriction, indicating that in cerebral
arterioles conduction may be mediated through endothelial cell
mechanisms rather than through smooth muscle cell communication.
Received 22 February 1995; accepted in final form 20 February
1996.
APS Manuscript Number H167-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 13 March 96