Afferent renal inputs onto subfornical organ neurons responsive to
angiotensin ii.
Ciriello, John.
Department of Physiology, Health Sciences Centre, University of
Western Ontario, London, Ontario, Canada, N6A 5C1
APStracts 3:0439R, 1996.
Experiments were done in pentobarbital sodium anesthetized rats to
investigate the effect of electrical stimulation of afferent renal
nerves (ARN) on the discharge rate of subfornical organ (SFO) neurons
that responded to changes in plasma levels of angiotensin II (ANG II)
and projected directly to the paraventricular nucleus of the
hypothalamus (PVH). Extracellular recordings were made from 76
histologically verified single neurons in the SFO that were excited
by intracarotid infusions of angiotensin II (ANG II). Of these units,
54.8% (23/42) responded with excitation to ARN stimulation ( mean
onset latency, 125 +/- 35 ms ). None of the SFO units excited by
plasma ANG II were found to be inhibited by ARN stimulation. An
additional 34 units in the SFO that were excited by plasma ANG II
were also antidromically activated by stimulation of the PVH. Of
these neurons, 17.8% (6/34) were also excited by stimulation of ARN.
The results indicate that inputs from ARN converge onto SFO neurons
that alter their discharge rate during changes in plasma
concentration of ANG II and project directly to the PVH. These data
suggest that ARN may play an important role in body fluid balance and
circulatory regulation by modulating the activity of SFO neurons that
function in the detection of blood-borne signals resulting from the
decrease in extracellular fluid volume and arterial pressure, and
that influence the activity of hypothalamic nuclei that contain
neurosecretory neurons.
Received 21 August 1996; accepted in final form 5 December 1996.
APS Manuscript Number R505-6.
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