Hc. Koh et al., MEDIATION OF THE CARDIOVASCULAR-RESPONSE OF ADENOSINE A(1) RECEPTOR THROUGH A GABA(B) RECEPTOR IN THE SPINAL-CORD OF THE RAT, Neuroscience letters, 243(1-3), 1998, pp. 81-84
Cardiovascular inhibitory effects induced by intrathecal (i.t.) admini
stration of adenosine A(1) receptor agonist and its modulation by cycl
ic AMP was suggested by our previous report. In this experiment, we ex
amined the mediation of cardiovascular effects of adenosine A(1) recep
tor by gamma-aminobutyric acid receptors A and B (GABA(A) and GABA(B))
in the spinal cord. I.t. administration of 10 nmol of N-6-cyclohexyla
denosine (CHA), an adenosine A(1) receptor agonist, and pretreatment w
ith bicuculline (10 nmol, i.t), a GABA(A) receptor antagonist, and 5-a
minovaleric acid (50 nmol, i.t.), a GABA(B) receptor antagonist, prior
to injection of CHA were performed in anesthetized, artificially vent
ilated Sprague-Dawley rats. I.t. injection of 50 nmol of 5-aminovaleri
c acid significantly attenuated the inhibitory cardiovascular effects
of CHA but 10 nmol of bicuculline did not alter CHA-induced cardiovasc
ular actions. It is suggested that cardiovascular responses of adenosi
ne A(1) receptor is meditated by GABA(B) receptor in the spinal cord.
(C) 1998 Published by Elsevier Science Ireland Ltd.