In vitro recordings from area postrema neurons demonstrate
responsiveness to adrenomedullin.
Allen, Mark A., and Alastair V. Ferguson.
Department of Physiology, Queen's University, Kingston, Ontario K7L
3N6
APStracts 3:0015R, 1996.
Adrenomedullin (ADM) is a recently discovered 52 amino acid peptide
which exerts potent vasodilatory effects in the periphery, and
influences the control of body fluid balance when injected centrally.
In this study extracellular single unit recordings were obtained from
94 AP neurons in rat brain slices. Bath application of ADM (10-7 M)
excited 47% (32 of 68) of cells tested and these effects were found
to be dose dependent from 10-7 M to 10-9 M. Excitation was maintained
during synaptic blockade in a low Ca2+ aCSF solution demonstrating
direct actions of ADM on these neurons. The remaining cells were
either unaffected (n=25) or inhibited (n=11) by ADM. ADM (10-7 M)
also influenced the spontaneous activity of 9 (7 inhibited, 2
excited) of 16 neurons located in the nucleus tractus solitarus
(NTS). However, these effects could be eliminated during synaptic
blockade suggesting indirect actions of the peptide on NTS neurons.
These data demonstrate that a specific population of CNS neurons
within the AP are directly influenced by ADM and suggest that ADM may
exert its effects on the central control of fluid balance through
direct actions at this circumventricular organ.
Received 30 October 1995; accepted in final form 28 December
1995.
APS Manuscript Number R669-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 22 January 96