C-fos expression in the medulla induced by static muscle
contraction in cats.
Li, Jianhua, Gregory A. Hand, Jeffrey T. Potts, L. Britt Wilson, and
Jere H. Mitchell.
Moss Heart Center and Department of Internal Medicine, University
of Texas Southwestern Medical Center, Dallas, TX 75235-9034
APStracts 3:0248H, 1996.
In this study, we examined Fos-like immunoreactivity (FLI) in the
medulla after static muscle contraction induced by stimulation of L7
and S1 ventral roots of the spinal cord in anesthetized cats. The
results show that FLI increases in the lateral reticular nucleus
(LRN), nucleus of the solitary tract (NTS), lateral tegmental field
(FTL), vestibular nucleus (VN), subretrofacial nucleus (SRF) and A1
region of the medulla in comparison with these same areas in sham
-operated animals (p<0.05 in each region). In the rostral
ventrolateral medulla, FLI distribution in neurons containing
phenylethanolamine-N-methyltransferase (PNMT, the synthetic enzyme
for epinephrine) were also observed utilizing double-labeling
methods. The majority of neurons with PNMT also expressed FLI (66+/
-4%). These data are in contrast to the results from sham-operated
animals showing that 24+/-3% of the neurons co-stained with PNMT
(p<0.05). Our findings indicate that expression of FLI can be
used to identify neurons activated during static muscle contraction,
and support previous studies implicating the ventrolateral medulla as
a critical region for expression of the exercise pressor reflex.
Further, neurons in the rostral ventrolateral medulla containing PNMT
were activated during static muscle contraction.
Received 22 January 1996; accepted in final form 6 June 1996.
APS Manuscript Number H3-6.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 28 June 96