Ng-nitro-l-arginine suppresses cerebrovascular response and evoked
potentials during somatosensory stimulation in the rat.
Ngai, Al C., Joseph R. Meno, and H. Richard Winn.
Department of Neurological Surgery, University of Washington School
of Medicine, Seattle, Washington 98104
APStracts 2:0255H, 1995.
We studied the local cerebrovascular response and somatosensory evoked
potentials (SEPs) to stimulation of the sciatic nerve during both
short-term (<30 min) and prolonged (90-150 min) exposure to
topically applied NG-nitro-L-arginine (L-NA). The pial circulation
was visualized through a cranial window in chloralose-anesthetized
rats. The diameter of pial arterioles (25-45 m) and laser-Doppler
flow (LDF) in the hindlimb sensory cortex were simultaneously
measured during stimulation of the sciatic nerve. Short-term
(<30 min) treatment with L-NA (1mM) abolished the dilation of
pial arterioles induced by acetylcholine, whereas the response to
sciatic nerve stimulation was not affected. When applied for >30
min, L-NA induced severe vasomotion, and attenuated the vascular
responses to sciatic nerve stimulation. Prolonged exposure to
topically (1 mM) or systemically (10 mg/kg, i.v.) applied L-NA also
attenuated cortical SEPs to sciatic nerve stimulation. Thus, L-NA
induced inhibition of vascular responses may be secondary to
suppression of neuronal activity, and an L-arginine metabolite, such
as NO, may be involved in neurotransmission in the cerebral cortex
during somatosensory activity.
Received 3 January 1995; accepted in final form 7 June 1995.
APS Manuscript Number H2-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 6 July 1995.