Central 5-ht1a modulation of cardiovascular responses to tibial
nerve stimulation-evoked muscle contraction .
Ally, Ahmmed, Daryl Caringi, David, M. Koester, Toshio Kobayashi, and
David J. Mokler.
Departments of Pharmacology, Biochemistry, and Anatomy, University
of New England College of Medicine, Biddeford, ME 04005, and The
Health Science Center, Tokyo University of Mercantile Marine, Tokyo,
Japan
APStracts 3:0411R, 1996.
The effects of administering 8-hydroxy-2-(di-N-propylamine)tetralin
(8-OH-DPAT, a 5-HT1A serotonin receptor agonist) into the rostral
ventrolateral medulla (rVLM) on cardiovascular responses during
tibial nerve stimulation-evoked muscle contraction were investigated
using anesthetized rats. Stimulation of the tibial nerve (3 times
motor threshold, 0.1 ms, 40 Hz) for 30 sec increased mean arterial
pressure (MAP), heart rate (HR), and muscle tension by 25+/-3 mmHg,
24+/-4 bpm, and 299+/-35 g, respectively. Bilateral microdialysis of
8-OH-DPAT (10 mM) for 30 min attenuated the stimulation-evoked
increases in MAP (8+/-2 mmHg) and HR (11+/-5 bpm), without a change
in muscle tension (292+/-30 g). However, administration of 1 mM 8-OH
-DPAT had no effect on the cardiovascular responses. Thirty minutes
microdialysis of 8-OH-DPAT (10 mM) into the caudal ventrolateral
medulla produced no effect on cardiovascular responses during muscle
contraction. Prior administration of 10 mM NAN-190 (1-(2
-methoxyphenyl)-4-[4-(2-phthalimido)butyl]piperazine), a 5-HT1A
receptor antagonist, for 30 min into the rVLM blocked the attenuating
effects of subsequent microdialysis of 8-OH-DPAT (10 mM). Results
suggest that activation of 5-HT1A receptors within the rVLM inhibit
cardiovascular responses elicited during static muscle contraction.
Received 8 October 1996; accepted in final form 7 November 1996.
APS Manuscript Number R609-6.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 31 December 1996