AJP - Regulatory, Integrative and Comparative Physiology, Vol 236, Issue 5 261-R267, Copyright © 1979 by American Physiological Society
Response of supraoptic neurosecretory cells to changes in left atrial distension
R. P. Menninger
Acute studies were conducted in cats to determine the effects of small
changes in left atrial pressure (LAP) on the activity of antidromically
identified neurons in the supraoptic nucleus (SON). Inflation of left
atrial balloons reproducibly altered the frequency of 15% of the SON
neurons. More than half of these increased frequency, probably due to a
simultaneous increase in arterial pressure. In a second series, the firing
rates of 20% of the SON neurons tested were inversely related to changes in
LAP produced by pumping blood into or out of the left atrium. A third
series of experiments were conducted in which the left atrium was directly
stretched by pulling on a suture placed in the atrial wall in addition to
one of the above methods of changing LAP. Directly stretching the left
atrium inhibited over 70% of the SON neurons; this included all the neurons
that responded to changes in LAP. The results suggest that these SON
neurons have differential sensitivities to inputs from left atrial
receptors.
