AJP - Regulatory, Integrative and Comparative Physiology, Vol 252, Issue 4 760-R767, Copyright © 1987 by American Physiological Society
Chemical microstimulation of the septal area lowers arterial pressure in the rat
A. J. Gelsema and F. R. Calaresu
Electrical stimulation of the septal area has been previously reported to
result in either an increase or a decrease in arterial pressure (AP) and
heart rate (HR) depending on the site of stimulation within the septum or
on the anesthetic. These conflicting results could be due to the different
proportions of cell bodies and fibers activated by electrical stimulation
at different sites and to the different anesthetics acting differently on
cell bodies and fibers. To study the cardiovascular responses to activation
of cell bodies, DL-homocysteate (20-50 nl) was injected into histologically
verified sites in the lateral septum (LS), the medial septum (MS), the
nucleus of the vertical limb of the diagonal band of Broca (NDBB), and in
the bed nucleus of the stria terminalis (BST) in urethananesthetized,
paralyzed, and artificially ventilated rats. Injections in the LS, MS, and
NDBB elicited a decrease in AP [-12.6 +/- 0.9 (SE) mmHg, n = 111]
accompanied by variable changes in HR. In a group of spontaneously
breathing rats anesthetized with urethan, AP responses were not
significantly different from those obtained in paralyzed animals. Finally,
in a group of animals under alpha-chloralose, AP responses were not
significantly different from those observed in animals under urethan.
Homocysteate application in the BST resulted in either depressor [-10.8 +/-
0.9 (SE) mmHg, n = 20] or pressor responses [13.7 +/- 1.9 (SE) mmHg, n =
9].(ABSTRACT TRUNCATED AT 250 WORDS)
