Clonidine modulates the ventrolateral medullary catechol metabolic hyperactivity induced by hypotension.
In vivo electrochemistry allowed recording of a catechol oxidation current in the ventrolateral medulla, caudal to the obex, in anesthetized rats whose ventilatory, metabolic and hemodynamic parameters were rigorously controlled. Hemorrhage or controlled hypotension induced an increase in the metabolism of catecholamines in the A1 noradrenergic group, which remained activated after full hemodynamic recovery. Clonidine (200 micrograms.kg-1 i.p.) given 30 min prior to hemorrhage or immediately before controlled hypotension suppressed partially the increased metabolism of catecholamines especially during the recovery period. This suggests that clonidine preserved phasic reactivity upon circulatory disturbances and decreased tonic hyperactivity following circulatory recovery.
Gillon
J Y
JY
Laboratoire de Neuropharmacologie (U.A. C.N.R.S. 1196), Faculté de Pharmacie, Université Claude Bernard, Lyon, France.
Quintin
L
L
Ghignone
M
M
Pujol
J F
JF
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D003000:Clonidine / Q000494:pharmacology*; D004563:Electrochemistry; D006339:Heart Rate / Q000187:drug effects; D007022:Hypotension / Q000139:chemically induced / Q000378:metabolism* / Q000503:physiopathology; D008297:Male; D008526:Medulla Oblongata / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology; D009599:Nitroprusside; D009638:Norepinephrine / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D009599:Nitroprusside; D003000:Clonidine; D009638:Norepinephrine