Mediation of the cardiovascular response to spinal gamma-aminobutyric acid(B) receptor stimulation by adenosine A(1) receptors in anesthetized rats.
Cardiovascular inhibitory effects induced by intrathecal (i.t.) administration of adenosine A(1) receptor agonist and its modulation by gamma-aminobutyric acid(B) (GABA(B)) receptor was suggested by our previous report. In this experiment, we examined the mediation of cardiovascular effects of GABA(B) receptor stimulation by adenosine A(1) and A(2) in the spinal cord. I.t. administration of GABA(B) receptor agonist, baclofen (30, 60 and 100 nmol) produced a dose dependent decrease of blood pressure and heart rate. Pretreatment with adenosine A(1) receptor antagonist, 8-cyclopentyl-1,3-dimethylxanthine (50 nmol), attenuated the depressor and bradycardiac effects of baclofen (100 nmol), but not with adenosine A(2) receptor antagonist, 3, 7-dimethyl-1-propargylxanthine (25 nmol). These results suggest that GABA(B) receptors in the spinal cord play an inhibitory role in the central cardiovascular regulation and that the depressor and bradycardiac actions are mediated by adenosine A(1) receptors.
Kim
B S
BS
Department of Pharmacology, College of Medicine, Hanyang University, 17 Haengdang-Dong, Sungdong-Ku, 133-791, Seoul, South Korea.
Koh
H C
HC
Kang
J S
JS
Lee
H
H
Shin
I C
IC
Om
S A
SA
Kang
J H
JH
D000241:Adenosine / Q000378:metabolism; D021542:Amino Acids, Neutral / Q000494:pharmacology; D000818:Animals; D001418:Baclofen / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D002320:Cardiovascular Physiological Phenomena / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D008297:Male; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D018080:Receptors, GABA-B / Q000187:drug effects* / Q000378:metabolism; D018047:Receptors, Purinergic P1 / Q000187:drug effects* / Q000378:metabolism; D013116:Spinal Cord / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D013564:Sympathetic Nervous System / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D013805:Theobromine / Q000031:analogs & derivatives* / Q000494:pharmacology; D013806:Theophylline / Q000031:analogs & derivatives* / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D021542:Amino Acids, Neutral; D018080:Receptors, GABA-B; D018047:Receptors, Purinergic P1; C053907:8-cyclopentyl-1,3-dimethylxanthine; D005680:gamma-Aminobutyric Acid; C057837:3,7-dimethyl-1-propargylxanthine; C013809:5-aminovaleric acid; D013806:Theophylline; D001418:Baclofen; D000241:Adenosine; D013805:Theobromine