AJP - Regulatory, Integrative and Comparative Physiology, Vol 237, Issue 1 63-R67, Copyright © 1979 by American Physiological Society
Effects of carotid occlusion and left atrial stretch on supraoptic neurosecretory cells
R. P. Menninger
Acute experiments were performed on pentobarbital-anesthetized cats to
determine whether atrial and carotid baroreceptors affected the same
neurosecretory neurons in the supraoptic nucleus (SON) of the hypothalamus.
The osmosensitivity of these neurons was also determined. Eighty-two SON
neurons were antidromically identified and 63 of these increased their
firing rates during complete occlusion of the right carotid artery. Further
testing of these 63 neurons demonstrated that 56 were inhibited by directly
stretching the left atrium and 61 were excited by intracarotid injection of
hypertonic saline. Left atrial stretch greatly reduced the neuronal
response to carotid occlusion. These results show that the activity of the
majority of the antidromically identified SON neurons is altered by left
atrial and carotid artery receptors as well as changes in plasma
osmolality. Results are consistent with the known influence of these
receptors on plasma vasopressin.
