Regional cerebral blood flow response to vibrissal stimulation in
mice lacking type i nos gene expression.
Ma, Jianya, Cenk Ayata, Paul L. Huang, Mark C. Fishman, Michael A.
Moskowitz.
Stroke and Neurovascular Regulation Laboratory, Neurosurgical
Services and Neurology Dept, Dept. of Surgery & Cardiovascular
Research Center Medical Services, Massachusetts General Hospital,
Harvard Medical School, Boston, MA 02114
APStracts 2:0392H, 1995.
The role of nitric oxide in cerebral blood flow-metabolism coupling
was assessed in SV-129 wild-type (Wt) and neuronal (type I) NOS
knockout mice (Kn). Regional cerebral blood flow (rCBF) (laser
Doppler flowmetry) was measured over the contralateral cortical
barrel field during unilateral mechanical vibrissal deflection (2-3
Hz; 60 sec) under urethane anesthesia. The rCBF response was similar
in Wt and Kn and did not differ when recorded over the intact skull
or closed cranial window preparations. Whisker stimulation increased
rCBF by 41+/-8% (maximum) and 27+/-6% (mean) in Wt (n=6), and 41+/-7%
(maximum) and 26+/-6% (mean) in Kn (n=6) when recorded through a
closed cranial window. After superfusion with topical nitro-L
-arginine (1 mM), the rCBF response was inhibited by 45% in Wt mice
(p<0.05) whereas there was no inhibition in Kn. Endothelium
-dependent relaxation, assessed by pial vessel dilation in response to
topical acetylcholine (10 [mu]M) and inhibition by L-NA (1 mM), was
the same in both groups. Our results suggest that, (1) endothelial NO
production does not mediate the rCBF coupling to neuronal activity in
Kn, (2) the inhibitory effect of L-NA on the rCBF response to whisker
stimulation in Wt is a consequence of type I (neuronal ) NOS
inhibition and (3) NO-independent mechanisms couple rCBF and
metabolism during whisker stimulation in mice lacking expression of
neuronal NOS.
Received 5 June 1995; accepted in final form 28 August 1995.
APS Manuscript Number H515-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 23 September 1995.