Participation of GABAergic mechanisms in the hypotensive and bradycardic effects of clonidine: experimental study in conscious normotensive and hypertensive rats.
In conscious rats with normal arterial blood pressure or with spontaneous or DOC induced hypertension, effects of drugs increasing (cycloserine, ethanolamine-o-sulphate, piracetam, chlordesmethyldiazepam) or depressing (bicuculline, Ro 15-1788, PK 11195) GABAergic reactivity were evaluated on the arterial hypotension and sinus bradycardia induced by clonidine. Clonidine was administered orally by gastric gavage (0.1-1 mg/kg). Pretreatment with cycloserine, ethanolamine-o-sulphate, piracetam or chlordesmethyldiazepam increased the hypotension and sinus bradycardia induced by clonidine. On the contrary, pretreatment with bicuculline or Ro 15-1788 reduced the cardiovascular effects of clonidine. These results suggest that the GABAergic system is involved in cardiovascular effects of clonidine in normotensive and hypertensive rats.
Marmo
E
E
Institute of Pharmacology and Toxicology, I Faculty of Medicine and Surgery, University of Naples, Italy.
Filippelli
W
W
Marrazzo
R
R
Russo
S
S
Cazzola
M
M
Vacca
C
C
Rossi
F
F
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D003000:Clonidine / Q000494:pharmacology*; D003900:Desoxycorticosterone; D006339:Heart Rate / Q000187:drug effects*; D006973:Hypertension / Q000139:chemically induced / Q000503:physiopathology*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D005680:gamma-Aminobutyric Acid / Q000502:physiology*
D003900:Desoxycorticosterone; D005680:gamma-Aminobutyric Acid; D003000:Clonidine