RESUMO
The study examined the effect of clonidine hydrochloride (10-9-10-5 Ð) on electrical activity of working cardiomyocytes in rat right atrium. Stimulation of α2-adrenergic receptor with clonidine changed electrical activity of the heart. All tested concentrations of the agonist lengthened the action potential and decreased the firing rate of cardiomyocytes in a dose-dependent manner. The maximum effects of clonidine were observed at concentration of 10-5 Ð.
Assuntos
Potenciais de Ação/efeitos dos fármacos , Agonistas de Receptores Adrenérgicos alfa 2/farmacologia , Clonidina/farmacologia , Miócitos Cardíacos/efeitos dos fármacos , Receptores Adrenérgicos alfa 2/fisiologia , Potenciais de Ação/fisiologia , Animais , Animais não Endogâmicos , Relação Dose-Resposta a Droga , Coração/efeitos dos fármacos , Coração/fisiologia , Átrios do Coração/citologia , Átrios do Coração/efeitos dos fármacos , Miócitos Cardíacos/citologia , Miócitos Cardíacos/fisiologia , Ratos , Técnicas de Cultura de TecidosRESUMO
The study examined the effects of hyperpolarization-activated funny current (If) on HR and coronary flow in Langendorff-isolated hearts from newborn rats. Blockade of If current with ZD7288 changed the examined cardiac parameters. The blocker in a concentration of 10-9 M decreased HR by 26.8% (p≤0.05). In concentrations 10-8, 10-7, 10-6, and 10-5 M ZD7288 produced minor differently directed effects. In a concentration of 10-5 M, ZD7288 reduced coronary flow in the isolated heart (p≤0.01). In other concentrations, the blocker produced no significant effects on coronary flow.
