TY - JOUR
T1 - Intrathecal kynurenate reduces arterial pressure, heart rate and baroreceptor-heart rate reflex in conscious rats
AU - Verberne, Anthony J.M.
AU - Widdop, Robert E.
AU - Maccarrone, Carlo
AU - Jarrott, Bevyn
AU - Beart, Philip M.
AU - Louis, William J.
PY - 1990/7/13
Y1 - 1990/7/13
N2 - In the present study, an excitatory amino acid (EAA) pathway in the spinal cord which maintains sympathetic vasomotor tone in conscious rats has been investigated. To this end, the cardiovascular effects of an intrathecally administered EAA antagonist, kynurenate (KYN), were studied in conscious rats. KYN (0.5 μmol in 10 μl) caused a dramatic reduction in mean arterial pressure (MAP) and heart rate (HR) that persisted for 2-3h, and also resulted in extensor paralysis of the hindlimbs. The time courses of fall in MAP and HR and hindlimb paralysis were similar. Baroreceptor-HR reflex activity was also markedly impaired after KYN, suggesting functional diminution of sympathetic outflow at the level of the spinal cord after blockade of EAA receptors by KYN. Xanthurenate, a metabolite of KYN without EAA antagonistic properties, produced negligible effects at the same dose of KYN. While these findings do not identify the putative EAA pathway, they do provide the first demonstration that this system is tonically active in conscious rats.
AB - In the present study, an excitatory amino acid (EAA) pathway in the spinal cord which maintains sympathetic vasomotor tone in conscious rats has been investigated. To this end, the cardiovascular effects of an intrathecally administered EAA antagonist, kynurenate (KYN), were studied in conscious rats. KYN (0.5 μmol in 10 μl) caused a dramatic reduction in mean arterial pressure (MAP) and heart rate (HR) that persisted for 2-3h, and also resulted in extensor paralysis of the hindlimbs. The time courses of fall in MAP and HR and hindlimb paralysis were similar. Baroreceptor-HR reflex activity was also markedly impaired after KYN, suggesting functional diminution of sympathetic outflow at the level of the spinal cord after blockade of EAA receptors by KYN. Xanthurenate, a metabolite of KYN without EAA antagonistic properties, produced negligible effects at the same dose of KYN. While these findings do not identify the putative EAA pathway, they do provide the first demonstration that this system is tonically active in conscious rats.
KW - Baroreceptor reflex
KW - Blood pressure
KW - Glutamate transmitter
KW - Intrathecal injection
KW - Kynurenate
KW - Rat
UR - http://www.scopus.com/inward/record.url?scp=0025324722&partnerID=8YFLogxK
U2 - 10.1016/0304-3940(90)90582-T
DO - 10.1016/0304-3940(90)90582-T
M3 - Article
C2 - 2402340
AN - SCOPUS:0025324722
SN - 0304-3940
VL - 114
SP - 309
EP - 315
JO - Neuroscience Letters
JF - Neuroscience Letters
IS - 3
ER -