[Influence of microinjection of bicuculline into ventrolateral medulla on the suppression of cardiac function induced by diazepam in rabbits].
Experiments were carried out on 48 rabbits anaesthetized with urethane (1 g/kg). The animals were immobilized with gallamine triethiodide and ventilated artificially. Both intravenous injection of diazepam (0.5 mg/kg) and intracerebroventricular injection of flurazepam (2 mg in 50 microliters) or gamma-aminobutyric acid (GABA) (300 micrograms in 50 microliters) decreased the peak value of left ventricular pressure area of cardiac force loop and dp/dtmax. These suppressive effects of diazepam and flurazepam were prevented by intracerebroventricular injection of picrotoxin (15 micrograms in 50 microliters) or microinjection of bicuculline (3 micrograms in 0.5 microliter) into bilateral rostral ventrolateral medulla (gamma VLM). The results suggest that the inhibitory effects of diazepam on cardiac function may be mediated by activation of GABA receptor in gamma VLM.
Fang
Z B
ZB
Su
H L
HL
Chen
C F
CF
Zhang
J F
JF
Guo
X Q
XQ
D000818:Animals; D001640:Bicuculline / Q000494:pharmacology*; D002316:Cardiotonic Agents; D003975:Diazepam / Q000494:pharmacology*; D005260:Female; D006321:Heart / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008526:Medulla Oblongata / Q000502:physiology*; D008845:Microinjections; D011817:Rabbits
D002316:Cardiotonic Agents; D003975:Diazepam; D001640:Bicuculline