Landiolol has a less potent negative inotropic effect than esmolol in isolated rabbit hearts.
OBJECTIVE
We compared the negative chronotropic and inotropic effects of landiolol and esmolol, two clinically available short-acting beta1-blockers with high beta1-selectivity, using whole isolated rabbit heart preparations.


METHODS
Tachycardia was induced by continuous perfusion of 10(-7) M isoproterenol, and we used concentrations of landiolol or esmolol in ascending steps (1 . 10(-6), 3 . 10(-6), 1 . 10(-5), 3 . 10(-5), and 1 x 10(-4) M). Heart rate (HR), left ventricular developed pressure (LVDP), the maximal rates of left ventricular force development (LVdP/dt(max)), and myocardial oxygen consumption (MVO2) were measured and compared.


RESULTS
Both landiolol and esmolol produced dosedependent decreases in HR, LVDP, LVdP/dt(max), and MVO2. The HR lowering effects of the two agents were comparable. At concentrations of 3 . 10(-5) and 1 . 10(-4) M, esmolol produced more profound depression of LVDP (47 +/- 26 and 12 +/- 11 mmHg, respectively; mean +/- SD) and reduction of LVdP/dt(max) (650 +/- 287 and 120 +/- 103 mmHg x s(-1)) than landiolol (68 +/- 20 and 64 +/- 20 mmHg, and 897 +/- 236 and 852 +/- 240 mmHg.s(-1), respectively). At the same concentrations, esmolol caused more profound reduction in MVO(2) (40 +/- 11 and 35 +/- 10 microl x min(-1) x g(-1)) than landiolol (50 +/- 8 and 48 +/- 8 microl x min(-1) x g(-1)), respectively.


CONCLUSIONS
Our results indicate that in the isolated rabbit heart, landiolol and esmolol had equipotent negative chronotropic effects, however, landiolol had a less potent negative inotropic effect than esmolol.
Ikeshita
Kazutoshi
K
Department of Anesthesiology, Yao Tokusyukai General Hospital, 3-15-38 Kyuhoji, Yao, Osaka, 581-0072, Japan.
Nishikawa
Kiyonobu
K
Toriyama
Sumiko
S
Yamashita
Tomoyuki
T
Tani
Yoshiyuki
Y
Yamada
Tokuhiro
T
Asada
Akira
A
D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009025:Morpholines / Q000494:pharmacology*; D009200:Myocardial Contraction / Q000187:drug effects*; D009206:Myocardium / Q000378:metabolism; D010101:Oxygen Consumption / Q000187:drug effects; D011412:Propanolamines / Q000494:pharmacology*; D011817:Rabbits; D014508:Urea / Q000031:analogs & derivatives* / Q000494:pharmacology; D016277:Ventricular Function, Left / Q000187:drug effects
D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D009025:Morpholines; D011412:Propanolamines; C077049:landiolol; D014508:Urea; D007545:Isoproterenol; C036604:esmolol