RESUMO
Effect of B-HT 920, a selective alpha 2 adrenoceptor agonist, was studied on ouabain induced cardiac arrhythmias and cardiac arrest in guinea pigs. Ventricular premature beats, ventricular tachyarrhythmias and cardiac arrest were induced in anaesthetized guinea pigs by slow infusion of ouabain. B-HT 920 accorded significant protection to guinea pigs against ouabain induced arrhythmias. Yohimbine inhibited the antiarrhythmic effect of B-HT 920 significantly. It is concluded that the protective effect of B-HT 920 against ouabain induced cardiac arrhythmias and cardiac arrest is mediated through the stimulation of alpha 2 adrenoceptors.
Assuntos
Agonistas alfa-Adrenérgicos/farmacologia , Animais , Arritmias Cardíacas/induzido quimicamente , Azepinas/farmacologia , Feminino , Cobaias , Coração/efeitos dos fármacos , Parada Cardíaca/induzido quimicamente , Masculino , Ouabaína/toxicidadeAssuntos
Acetilcolina/farmacologia , Animais , Pressão Sanguínea/efeitos dos fármacos , Sistema Cardiovascular/efeitos dos fármacos , Gatos , Dimetil Sulfóxido/farmacologia , Relação Dose-Resposta a Droga , Interações Medicamentosas , Feminino , Cobaias , Frequência Cardíaca/efeitos dos fármacos , Íleo/efeitos dos fármacos , Masculino , Camundongos , Atividade Motora/efeitos dos fármacos , Contração Muscular/efeitos dos fármacos , Ratos , Serotonina/farmacologia , Solventes/farmacologia , Útero/efeitos dos fármacosRESUMO
ST-93, a clonidine analog was studied for its antiarrhythmic activity in anaesthetised guinea pigs against ouabain induced arrhythmia. The amount of ouabain required (micrograms/kg) for the production of ventricular premature best. Ventricular fibrillation and cardiac arrest was recorded in control and drug treated group of animals. Both ST-93 and clonidine produced significant antiarrhythmic effect in guinea pigs. This protective effect was significantly blocked by yohimbine, suggesting that the antiarrhythmic effect is mediated through presynaptic alpha 2-adrenoceptors.
Assuntos
Animais , Antiarrítmicos/farmacologia , Arritmias Cardíacas/prevenção & controle , Clonidina/análogos & derivados , Feminino , Cobaias , Hemodinâmica/efeitos dos fármacos , Masculino , Ouabaína , Ioimbina/farmacologiaRESUMO
Dimethylformamide (DMF) is widely used as a drug solvent. We found DMF to have wide-spread pharmacological effects including depressant effect on CNS evidenced by a decrease in locomotor activity, body and limb tone and rectal temperature, and potentiation of pentobarbitone sleep. A dose-dependent hypotensive effect was seen in cats and rats. In rats, it was partially blocked by atropine and was associated with bradycardia. DMF antagonised the contractions of smooth muscle induced by many agonists. An atropine sensitive spasmogenic effect was observed on rabbit ileum at 20 ml/l and a direct relaxant effect at 50 ml/l. A positive inotropic effect on guinea pig atria was observed with 5 ml/l. The results indicate DMF concentrations that may not perhaps produce 'solvent artifacts' when used as a solvent.