Mediation of the cardiovascular response of adenosine A1 receptor through a GABA(B) receptor in the spinal cord of the rat.
Cardiovascular inhibitory effects induced by intrathecal (i.t.) administration of adenosine A1 receptor agonist and its modulation by cyclic AMP was suggested by our previous report. In this experiment, we examined the mediation of cardiovascular effects of adenosine A1 receptor by gamma-aminobutyric acid receptors A and B [GABA(A) and GABA(B)] in the spinal cord. I.t. administration of 10 nmol of N6-cyclohexyladenosine (CHA), an adenosine A1 receptor agonist, and pretreatment with bicuculline (10 nmol, i.t), a GABA(A) receptor antagonist, and 5-aminovaleric acid (50 nmol, i.t.), a GABA(B) receptor antagonist, prior to injection of CHA were performed in anesthetized, artificially ventilated Sprague-Dawley rats. I.t. injection of 50 nmol of 5-aminovaleric acid significantly attenuated the inhibitory cardiovascular effects of CHA but 10 nmol of bicuculline did not alter CHA-induced cardiovascular actions. It is suggested that cardiovascular responses of adenosine A1 receptor is mediated by GABA(B) receptor in the spinal cord.
Koh
H C
HC
Department of Pharmacology, College of Medicine, Hanyang University, Seoul, South Korea.
Shin
I C
IC
Hwang
S J
SJ
Kang
J S
JS
Lee
C H
CH
Ha
J H
JH
Paik
D J
DJ
D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology; D000596:Amino Acids / Q000494:pharmacology; D021542:Amino Acids, Neutral; D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D002319:Cardiovascular System / Q000294:innervation*; D000242:Cyclic AMP / Q000378:metabolism; D018756:GABA Antagonists / Q000494:pharmacology; D058787:GABA-A Receptor Antagonists; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D058906:Purinergic P1 Receptor Agonists; D051381:Rats; D017207:Rats, Sprague-Dawley; D011963:Receptors, GABA-A / Q000378:metabolism; D018080:Receptors, GABA-B / Q000378:metabolism*; D018047:Receptors, Purinergic P1 / Q000378:metabolism*; D013116:Spinal Cord / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*
D000596:Amino Acids; D021542:Amino Acids, Neutral; D018756:GABA Antagonists; D058787:GABA-A Receptor Antagonists; D058906:Purinergic P1 Receptor Agonists; D011963:Receptors, GABA-A; D018080:Receptors, GABA-B; D018047:Receptors, Purinergic P1; C027513:N(6)-cyclohexyladenosine; C013809:5-aminovaleric acid; D000242:Cyclic AMP; D000241:Adenosine; D001640:Bicuculline