Protective effects of centrally acting sympathomodulatory drugs on myocardial ischemia induced by sympathetic overactivity in rabbits
Braz. j. med. biol. res
;
36(1): 85-95, Jan. 2003. ilus, tab, graf
Artigo
em Inglês
| LILACS
| ID: lil-326316
ABSTRACT
It is recognized that an imbalance of the autonomic nervous system is involved in the genesis of ventricular arrhythmia and sudden death during myocardial ischemia. In the present study we investigated the effects of clonidine and rilmenidine, two centrally acting sympathomodulatory drugs, on an experimental model of centrally induced sympathetic hyperactivity in pentobarbital-anesthetized New Zealand albino rabbits of either sex (2-3 kg, N = 89). We also compared the effects of clonidine and rilmenidine with those of propranolol, a á-blocker, known to induce protective cardiovascular effects in patients with ischemic heart disease. Central sympathetic stimulation was achieved by intracerebroventricular injection of the excitatory amino acid L-glutamate (10 æmol), associated with inhibition of nitric oxide synthesis with L-NAME (40 mg/kg, iv). Glutamate triggered ventricular arrhythmia and persistent ST-segment shifts in the ECG, indicating myocardial ischemia. The intracisternal administration of clonidine (1 æg/kg) and rilmenidine (30 æg/kg) or of a nonhypotensive dose of rilmenidine (3 æg/kg) decreased the incidence of myocardial ischemia (25, 14 and 25 percent, respectively, versus 60 percent in controls) and reduced the mortality rate from 40 percent to 0.0, 0.0 and 12 percent, respectively. The total number of ventricular premature beats per minute fell from 30 ± 9 in the control group to 7 ± 3, 6 ± 3 and 2 ± 2, respectively. Intravenous administration of clonidine (10 æg/kg), rilmenidine (300 æg/kg) or propranolol (500 æg/kg) elicited similar protective effects. We conclude that clonidine and rilmenidine present cardioprotective effects of central origin, which can be reproduced by propranolol, a lipophilic á-blocking agent
Texto completo:
DisponíveL
Índice:
LILACS (Américas)
Assunto principal:
Propranolol
/
Sistema Nervoso Simpático
/
Isquemia Miocárdica
/
Antagonistas Adrenérgicos beta
/
Anti-Hipertensivos
Limite:
Animais
Idioma:
Inglês
Revista:
Braz. j. med. biol. res
Assunto da revista:
Biologia
/
Medicina
Ano de publicação:
2003
Tipo de documento:
Artigo
/
Documento de projeto
País de afiliação:
Brasil
/
França
Instituição/País de afiliação:
FIOCRUZ/BR
/
Université Louis Pasteur/FR
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