AI Article Synopsis
- This study investigated the effects of pimobendan, a calcium sensitizer, on force-frequency response (FFR) in comparison to dobutamine, a beta-adrenergic agonist, in dogs with heart failure.
- Results showed that while both drugs had similar effects on contractility and relaxation initially, dobutamine significantly enhanced FFR more than pimobendan.
- The findings suggest that pimobendan could be a safer option for increasing heart rates during activities like exercise, due to its milder FFR amplification compared to dobutamine.
Article Abstract
Background: This study was designed to examine how a calcium sensitizer, pimobendan, affected a force-frequency response (FFR) as compared to the beta-adrenergic agonist dobutamine.
Methods And Results: Left ventricular (LV) contractility and relaxation were evaluated by the slope (Ees) of the LV end-systolic pressure-volume relation and the time constant (Tau) of LV pressure decay. Using 6 conscious dogs with tachycardia-induced heart failure, the FFR was examined before and after administration of dobutamine (6 microg/kg/min) or pimobendan (0.5 mg/kg). Despite the similar inotropic and lusitropic action at the baseline heart rate, pimobendan and dobutamine showed different FFR and relaxation-frequency responses. Before administration of these drugs, there was no significant increase in LV contractility and relaxation by increasing heart rate. However, dobutamine amplified FFR (Ees: +3.1 +/- 1.4, P <.05) as compared with Ees for a comparable increase in heart rate before administration of the drug. On the other hand, pimobendan showed relatively mild amplification of FFR compared with dobutamine (Ees: +1.9 +/- 1.1, P <.05). The relaxation-frequency response tended to increase with dobutamine but not with pimobendan.
Conclusions: Mild amplification of FFR observed in pimobendan suggests that this agent could be used more safely than beta-adrenergic agent when heart rate is increased, as seen with exercise.
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| http://dx.doi.org/10.1054/jcaf.2002.129658 | DOI Listing |
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