Chemical stimulation of the nucleus tractus solitarii decreases spinal cord blood flow in anesthetized rats.
L-Glutamate was microinjected into the nucleus tractus solitarii (NTS) in anesthetized (chloralose and urethane), paralyzed and artificially ventilated rats, and spinal cord blood flow (SCBF) was determined using a combination of labeled microspheres. Unilateral chemical stimulation of the NTS (n = 13) significantly decreased SCBF in the cervical cord from 43 +/- 6 (mean +/- SEM) to 28 +/- 4 (P < 0.05), in the thoracic cord from 35 +/- 3 to 24 +/- 4 (P < 0.01), and in the lumbar cord from 49 +/- 3 to 40 +/- 3 ml min-1 (100 g)-1 (P < 0.05). The decrease in SCBF was not due to the decrease in arterial blood pressure (ABP) because the SCBF during the chemical stimulation of the NTS was significantly smaller (P < 0.05) than the SCBF during controlled hemorrhagic hypotension (n = 11). Chemical stimulation of the NTS did not affect the reactivity of the spinal cord vessels to hypercapnia (n = 5). Microinjection of the vehicle solution into the NTS had no effects on spinal cord circulation (n = 9). These results suggest that the cell bodies within the NTS may play a role in the control of spinal cord circulation.
Maeda
M
M
Department of Systems Physiology, University of Occupational and Environmental Health, Kitakyushu, Japan.
Inoue
M
M
Takao
S
S
Ikegami
Y
Y
Nakai
M
M
Krieger
A J
AJ
Sapru
H N
HN
Hayashida
Y
Y
D000818:Animals; D001783:Blood Flow Velocity; D018698:Glutamic Acid / Q000494:pharmacology; D006470:Hemorrhage; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D017552:Solitary Nucleus / Q000502:physiology*; D013116:Spinal Cord / Q000502:physiology*; D013268:Stimulation, Chemical
D018698:Glutamic Acid