RESUMO
The ß-blockers carvedilol and metoprolol provide important therapeutic strategies for heart failure treatment. Therapy with metoprolol facilitates the control by phosphodiesterase PDE3, but not PDE4, of inotropic effects of catecholamines in human failing ventricle. However, it is not known whether carvedilol has the same effect. We investigated whether the PDE3-selective inhibitor cilostamide (0.3 µM) or PDE4-selective inhibitor rolipram (1 µM) modified the positive inotropic and lusitropic effects of catecholamines in ventricular myocardium of heart failure patients treated with carvedilol. Right ventricular trabeculae from explanted hearts of nine carvedilol-treated patients with terminal heart failure were paced to contract at 1 Hz. The effects of (-)-noradrenaline, mediated through ß1-adrenoceptors (ß2-adrenoceptors blocked with ICI118551), and (-)-adrenaline, mediated through ß2-adrenoceptors (ß1-adrenoceptors blocked with CGP20712A), were assessed in the absence and presence of the PDE inhibitors. The inotropic potency, estimated from -logEC50s, was unchanged for (-)-noradrenaline but decreased 16-fold for (-)-adrenaline in carvedilol-treated compared to non-ß-blocker-treated patients, consistent with the previously reported ß2-adrenoceptor-selectivity of carvedilol. Cilostamide caused 2- to 3-fold and 10- to 35-fold potentiations of the inotropic and lusitropic effects of (-)-noradrenaline and (-)-adrenaline, respectively, in trabeculae from carvedilol-treated patients. Rolipram did not affect the inotropic and lusitropic potencies of (-)-noradrenaline or (-)-adrenaline. Treatment of heart failure patients with carvedilol induces PDE3 to selectively control the positive inotropic and lusitropic effects mediated through ventricular ß2-adrenoceptors compared to ß1-adrenoceptors. The ß2-adrenoceptor-selectivity of carvedilol may provide protection against ß2-adrenoceptor-mediated ventricular overstimulation in PDE3 inhibitor-treated patients. PDE4 does not control ß1- and ß2-adrenoceptor-mediated inotropic and lusitropic effects in carvedilol-treated patients.
Assuntos
Antagonistas Adrenérgicos beta/farmacologia , Carbazóis/farmacologia , Nucleotídeo Cíclico Fosfodiesterase do Tipo 3/fisiologia , Insuficiência Cardíaca/fisiopatologia , Propanolaminas/farmacologia , Receptores Adrenérgicos beta 1/fisiologia , Receptores Adrenérgicos beta 2/fisiologia , Adulto , Carvedilol , Nucleotídeo Cíclico Fosfodiesterase do Tipo 4/fisiologia , Epinefrina/farmacologia , Feminino , Transplante de Coração , Humanos , Masculino , Pessoa de Meia-Idade , Norepinefrina/farmacologia , Inibidores da Fosfodiesterase 3/farmacologia , Inibidores da Fosfodiesterase 4/farmacologia , Quinolonas/farmacologia , Rolipram/farmacologiaRESUMO
BACKGROUND AND PURPOSE: PDE3 and/or PDE4 control ventricular effects of catecholamines in several species but their relative effects in failing human ventricle are unknown. We investigated whether the PDE3-selective inhibitor cilostamide (0.3-1 µM) or PDE4 inhibitor rolipram (1-10 µM) modified the positive inotropic and lusitropic effects of catecholamines in human failing myocardium. EXPERIMENTAL APPROACH: Right and left ventricular trabeculae from freshly explanted hearts of 5 non-ß-blocker-treated and 15 metoprolol-treated patients with terminal heart failure were paced to contract at 1 Hz. The effects of (-)-noradrenaline, mediated through ß1 adrenoceptors (ß2 adrenoceptors blocked with ICI118551), and (-)-adrenaline, mediated through ß2 adrenoceptors (ß1 adrenoceptors blocked with CGP20712A), were assessed in the absence and presence of PDE inhibitors. Catecholamine potencies were estimated from -logEC50s. KEY RESULTS: Cilostamide did not significantly potentiate the inotropic effects of the catecholamines in non-ß-blocker-treated patients. Cilostamide caused greater potentiation (P = 0.037) of the positive inotropic effects of (-)-adrenaline (0.78 ± 0.12 log units) than (-)-noradrenaline (0.47 ± 0.12 log units) in metoprolol-treated patients. Lusitropic effects of the catecholamines were also potentiated by cilostamide. Rolipram did not affect the inotropic and lusitropic potencies of (-)-noradrenaline or (-)-adrenaline on right and left ventricular trabeculae from metoprolol-treated patients. CONCLUSIONS AND IMPLICATIONS: Metoprolol induces a control by PDE3 of ventricular effects mediated through both ß1 and ß2 adrenoceptors, thereby further reducing sympathetic cardiostimulation in patients with terminal heart failure. Concurrent therapy with a PDE3 blocker and metoprolol could conceivably facilitate cardiostimulation evoked by adrenaline through ß2 adrenoceptors. PDE4 does not appear to reduce inotropic and lusitropic effects of catecholamines in failing human ventricle.