Stroke, Vol 8, 391-392, Copyright © 1977 by American Heart Association
WI Rosenblum and M Chen
Alpha methyl tryosine (AMT), and inhibitor of norepinephrine (NOR)
synthesis, was injected intraperitoneally (200 mg/kg) in Sprague Dawley
rats, kept in a cold room, or at room temperature for 16 hours. Using
formaldehyde induced NOR fluorescence, nerve counts were made on whole
mounts of cerebral and femoral arterioles 14-300 micronm in diameter,
utilizing a grid superimposed on the vessels. Cold had no effect on the
number of visible (i.e. fluorescing) nerves. AMT had an appreciable effect
but only on nerves to femoral arterioles, where a significant reduction in
nerve count was observed in both cold stressed and non stressed rates, when
compared with animals not given AMT. Since the counting technique is
sensitive only to large depletions of NOR, we cannot conclude that AMT
failed to affect NOR content in cerebrovascular nerves. However, if such an
effect was present, it was much less than the effect of AMT on nerves to
femoral vessels. We suggest that the differential effect of AMT on these 2
vascular beds may indicate a lower basal level of NOR release from
cerebrovascular nerves, which would correlate with the difficulty of
demonstrating basal sympathetic tone in this vascular bed.
ARTICLES
Comparison of nerves to cerebral and extracerebral blood vessels: a differential effect of alpha methyl tyrosine on norepinephrine content
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