Background: Halogenated anesthetics potentiate the positive inotropic effec
ts of alpha- and beta-adrenoceptor stimulations, but their interactions wit
h 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 papil
lary 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 percentag
e of baseline a SD.
Results: Dobutamine induced a positive inotropic effect (active isometric f
orce: 185 +/- 36%, P < 0.001) and a positive lusitropic effect under low lo
ad (R1: 78 +/- 9%, P < 0.001), but not under high load (R2: 95 +/- 21%, not
significant). Halothane, isoflurane, and sevoflurane did not modify the po
sitive inotropic effect of dobutamine, Even in the presence of alpha-adreno
ceptor blockade, isoflurane did not potentiate the positive inotropic effec
t of dobutamine, Desflurane significantly enhanced the positive inotropic e
ffect of dobutamine (active isometric force: 239 +/- 35%, P < 0.001), but t
his 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 desflur
ane-induced release in intramyocardial catecholamine stores.