Interaction of halogenated anesthetics with dobutamine in rat myocardium

Background: Halogenated anesthetics potentiate the positive inotropic effects of alpha- and beta-adrenoceptor stimulations, but their interactions with dobutamine remain unknown. Methods: The effects of halothane, isoflurane, sevoflurane, and desflurane (1 and 2 minimum alveolar concentration) on the inotropic responses induced by dobutamine (10(-8)-10(-4) M) were studied in rat left ventricular papillary muscles irt vitro. Inotropic effects were studied under low (isotony) and high (isometry) loads. The authors also studied the lusitropic effects in isotonic (R1) and isometric (R2) conditions, Data are the mean percentage of baseline a SD. Results: Dobutamine induced a positive inotropic effect (active isometric force: 185 +/- 36%, P < 0.001) and a positive lusitropic effect under low load (R1: 78 +/- 9%, P < 0.001), but not under high load (R2: 95 +/- 21%, not significant). Halothane, isoflurane, and sevoflurane did not modify the positive inotropic effect of dobutamine, Even in the presence of alpha-adrenoceptor blockade, isoflurane did not potentiate the positive inotropic effect of dobutamine, Desflurane significantly enhanced the positive inotropic effect of dobutamine (active isometric force: 239 +/- 35%, P < 0.001), but this potentiation was abolished by pretreatment with reserpine. In contrast to halothane, isoflurane, sevoflurane, and desflurane did not significantly modify the lusitropic effects of dobutamine, Conclusions: Halogenated anesthetics, except desflurane, did not modify the positive inotropic effects of dobutamine. Desflurane enhanced the positive inotropic effect of dobutamine, but this effect was related to the desflurane-induced release in intramyocardial catecholamine stores.