A source of adenosine involved in cardiovascular responses to
defence area stimulation.
Lambert, J. H. St, Thomas, T., Burnstock, G. & Spyer, K. M.
Department of Physiology, Royal Free Hospital School of Medicine,
Rowland Hill Street, London, NW3 2PF and Department of Anatomy and
Developmental Biology, University College London, Gower Street,
London WC1E 6BT
APStracts 3:0189R, 1996.
We have investigated the source of central adenosine important in
modulating the cardiovascular response to hypothalamic defence area
(HDA) stimulation in [alpha]-chloralose anaesthetized rats.
Microinjections of an ecto-5'-nucleotidase inhibitor, [alpha],[beta]
-methylene ADP ([alpha],[beta]-meADP), were made into caudal nucleus
tractus solitarii (cNTS) and rostral ventrolateral medulla (RVLM) and
its effects on HDA evoked responses observed. Stimulation of HDA
evoked an increase in arterial pressure and a secondary rise in
arterial pressure after stimulation ceased. There was also an
increase in heart rate and hindlimb blood flow. [alpha],[beta]-meADP
had no effect on resting levels of arterial pressure, heart rate and
hindlimb blood flow when injected into cNTS or RVLM. [alpha],[beta]
-meADP also had no effect on the HDA evoked tachycardia and increase
in muscle blood flow. However, [alpha],[beta]-meADP reduced the
primary increase in arterial pressure evoked by HDA stimulation when
microinjected into cNTS. In contrast, [alpha],[beta]-meADP reduced
the secondary increase in arterial pressure when microinjected into
RVLM. From these results we suggest that at least part of the
adenosine released centrally during HDA stimulation is derived
extracellularly from ATP metabolism.
Received 18 September 1995; accepted in final form 17 April 1996.
APS Manuscript Number R577-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 28 May 96